diff --git a/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkRuleClassFunctions.java b/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkRuleClassFunctions.java
index 7100116..aaef7d5 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkRuleClassFunctions.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkRuleClassFunctions.java
@@ -307,6 +307,10 @@
 
     // We'll set the name later, pass the empty string for now.
     RuleClass.Builder builder = new RuleClass.Builder("", type, true, parent);
+
+    ImmutableList<StarlarkThread.CallStackEntry> callstack = thread.getCallStack();
+    builder.setCallStack(callstack.subList(0, callstack.size() - 1)); // pop 'rule' itself
+
     ImmutableList<Pair<String, SkylarkAttr.Descriptor>> attributes =
         attrObjectToAttributesList(attrs);
 
@@ -661,8 +665,8 @@
             pkgContext,
             ruleClass,
             attributeValues,
-            thread.getCallerLocation(),
-            thread,
+            thread.getSemantics(),
+            thread.getCallStack(),
             new AttributeContainer(ruleClass));
       } catch (InvalidRuleException | NameConflictException e) {
         throw new EvalException(null, e.getMessage());
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/repository/RepositoryResolvedEvent.java b/src/main/java/com/google/devtools/build/lib/bazel/repository/RepositoryResolvedEvent.java
index 9838e9b..a77d6fa 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/repository/RepositoryResolvedEvent.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/repository/RepositoryResolvedEvent.java
@@ -21,7 +21,6 @@
 import static com.google.devtools.build.lib.rules.repository.ResolvedHashesFunction.REPOSITORIES;
 import static com.google.devtools.build.lib.rules.repository.ResolvedHashesFunction.RULE_CLASS;
 
-import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.lib.events.ExtendedEventHandler.ResolvedEvent;
@@ -31,6 +30,7 @@
 import com.google.devtools.build.lib.syntax.EvalException;
 import com.google.devtools.build.lib.syntax.Printer;
 import com.google.devtools.build.lib.syntax.Starlark;
+import com.google.devtools.build.lib.syntax.StarlarkThread;
 import com.google.devtools.build.lib.util.Pair;
 import com.google.devtools.build.lib.vfs.Path;
 import java.io.IOException;
@@ -82,10 +82,7 @@
     String originalClass =
         rule.getRuleClassObject().getRuleDefinitionEnvironmentLabel() + "%" + rule.getRuleClass();
     resolvedInformationBuilder.put(ORIGINAL_RULE_CLASS, originalClass);
-
-    if (!Strings.isNullOrEmpty(rule.getDefinitionInformation())) {
-      resolvedInformationBuilder.put(DEFINITION_INFORMATION, rule.getDefinitionInformation());
-    }
+    resolvedInformationBuilder.put(DEFINITION_INFORMATION, getRuleDefinitionInformation(rule));
 
     ImmutableMap.Builder<String, Object> origAttrBuilder = ImmutableMap.builder();
     ImmutableMap.Builder<String, Object> defaults = ImmutableMap.builder();
@@ -218,6 +215,35 @@
     return message;
   }
 
+  /** Returns an unstructured message explaining the origin of this rule. */
+  public static String getRuleDefinitionInformation(Rule rule) {
+    StringBuilder buf = new StringBuilder();
+
+    // Emit stack of rule instantiation.
+    buf.append("Repository ").append(rule.getName()).append(" instantiated at:\n");
+    ImmutableList<StarlarkThread.CallStackEntry> stack = rule.getCallStack().toList();
+    if (stack.isEmpty()) {
+      buf.append("  no stack (--record_rule_instantiation_callstack not enabled)\n");
+    } else {
+      for (StarlarkThread.CallStackEntry frame : stack) {
+        buf.append("  ").append(frame.location).append(": in ").append(frame.name).append('\n');
+      }
+    }
+
+    // Emit stack of rule class declaration.
+    stack = rule.getRuleClassObject().getCallStack();
+    if (stack.isEmpty()) {
+      buf.append("Repository rule ").append(rule.getRuleClass()).append(" is built-in.\n");
+    } else {
+      buf.append("Repository rule ").append(rule.getRuleClass()).append(" defined at:\n");
+      for (StarlarkThread.CallStackEntry frame : stack) {
+        buf.append("  ").append(frame.location).append(": in ").append(frame.name).append('\n');
+      }
+    }
+
+    return buf.toString();
+  }
+
   /**
    * Compare two maps from Strings to objects, returning a pair of the map with all entries not in
    * the original map or in the original map, but with a different value, and the keys dropped from
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/repository/skylark/SkylarkRepositoryFunction.java b/src/main/java/com/google/devtools/build/lib/bazel/repository/skylark/SkylarkRepositoryFunction.java
index 41975a5..899f3fd 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/repository/skylark/SkylarkRepositoryFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/repository/skylark/SkylarkRepositoryFunction.java
@@ -15,7 +15,6 @@
 package com.google.devtools.build.lib.bazel.repository.skylark;
 
 import com.google.common.base.Preconditions;
-import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
@@ -99,12 +98,10 @@
       Map<String, String> markerData,
       SkyKey key)
       throws RepositoryFunctionException, InterruptedException {
-    if (rule.getDefinitionInformation() != null) {
-      env.getListener()
-          .post(
-              new SkylarkRepositoryDefinitionLocationEvent(
-                  rule.getName(), rule.getDefinitionInformation()));
-    }
+
+    String defInfo = RepositoryResolvedEvent.getRuleDefinitionInformation(rule);
+    env.getListener().post(new SkylarkRepositoryDefinitionLocationEvent(rule.getName(), defInfo));
+
     StarlarkFunction function = rule.getRuleClassObject().getConfiguredTargetFunction();
     if (declareEnvironmentDependencies(markerData, env, getEnviron(rule)) == null) {
       return null;
@@ -212,7 +209,7 @@
               rule, skylarkRepositoryContext.getAttr(), outputDirectory, result);
       if (resolved.isNewInformationReturned()) {
         env.getListener().handle(Event.debug(resolved.getMessage()));
-        env.getListener().handle(Event.debug(rule.getDefinitionInformation()));
+        env.getListener().handle(Event.debug(defInfo));
       }
 
       String ruleClass =
@@ -248,9 +245,9 @@
                       + rule.getName()
                       + "':\n   "
                       + e.getMessage()));
-      if (!Strings.isNullOrEmpty(rule.getDefinitionInformation())) {
-        env.getListener().handle(Event.info(rule.getDefinitionInformation()));
-      }
+      env.getListener()
+          .handle(Event.info(RepositoryResolvedEvent.getRuleDefinitionInformation(rule)));
+
       throw new RepositoryFunctionException(e, Transience.TRANSIENT);
     }
 
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/repository/skylark/SkylarkRepositoryModule.java b/src/main/java/com/google/devtools/build/lib/bazel/repository/skylark/SkylarkRepositoryModule.java
index 8bedec7..ff4cc57 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/repository/skylark/SkylarkRepositoryModule.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/repository/skylark/SkylarkRepositoryModule.java
@@ -20,12 +20,11 @@
 import static com.google.devtools.build.lib.packages.Type.STRING_LIST;
 import static com.google.devtools.build.lib.syntax.SkylarkType.castMap;
 
-import com.google.common.collect.Lists;
+import com.google.common.collect.ImmutableList;
 import com.google.devtools.build.lib.analysis.BaseRuleClasses;
 import com.google.devtools.build.lib.analysis.skylark.SkylarkAttr.Descriptor;
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
-import com.google.devtools.build.lib.events.Location;
 import com.google.devtools.build.lib.packages.AttributeValueSource;
 import com.google.devtools.build.lib.packages.BazelStarlarkContext;
 import com.google.devtools.build.lib.packages.Package;
@@ -73,6 +72,10 @@
     // We'll set the name later, pass the empty string for now.
     RuleClass.Builder builder = new RuleClass.Builder("", RuleClassType.WORKSPACE, true);
 
+    ImmutableList<StarlarkThread.CallStackEntry> callstack = thread.getCallStack();
+    builder.setCallStack(
+        callstack.subList(0, callstack.size() - 1)); // pop 'repository_rule' itself
+
     builder.addOrOverrideAttribute(attr("$local", BOOLEAN).defaultValue(local).build());
     builder.addOrOverrideAttribute(attr("$configure", BOOLEAN).defaultValue(configure).build());
     if (thread.getSemantics().experimentalRepoRemoteExec()) {
@@ -105,7 +108,7 @@
         (Label) Module.ofInnermostEnclosingStarlarkFunction(thread).getLabel(),
         thread.getTransitiveContentHashCode());
     builder.setWorkspaceOnly();
-    return new RepositoryRuleFunction(builder, thread.getCallerLocation(), implementation);
+    return new RepositoryRuleFunction(builder, implementation);
   }
 
   // RepositoryRuleFunction is the result of repository_rule(...).
@@ -113,17 +116,12 @@
   private static final class RepositoryRuleFunction extends BaseFunction
       implements SkylarkExportable {
     private final RuleClass.Builder builder;
+    private final BaseFunction implementation;
     private Label extensionLabel;
     private String exportedName;
-    private final Location ruleClassDefinitionLocation;
-    private final BaseFunction implementation;
 
-    private RepositoryRuleFunction(
-        RuleClass.Builder builder,
-        Location ruleClassDefinitionLocation,
-        BaseFunction implementation) {
+    private RepositoryRuleFunction(RuleClass.Builder builder, BaseFunction implementation) {
       this.builder = builder;
-      this.ruleClassDefinitionLocation = ruleClassDefinitionLocation;
       this.implementation = implementation;
     }
 
@@ -192,35 +190,18 @@
         PackageContext context = PackageFactory.getContext(thread);
         Package.Builder packageBuilder = context.getBuilder();
 
-        // TODO(adonovan): is this safe? Check.
-        String externalRepoName = (String) kwargs.get("name");
-
-        StringBuilder callStack =
-            new StringBuilder("Call stack for the definition of repository '")
-                .append(externalRepoName)
-                .append("' which is a ")
-                .append(ruleClassName)
-                .append(" (rule definition at ")
-                .append(ruleClassDefinitionLocation.toString())
-                .append("):");
-        for (StarlarkThread.CallStackEntry frame : Lists.reverse(thread.getCallStack())) {
-          callStack.append("\n - ").append(frame.location);
-        }
-
-        WorkspaceFactoryHelper.addMainRepoEntry(
-            packageBuilder, externalRepoName, thread.getSemantics());
-
-        Location loc = thread.getCallerLocation();
-        WorkspaceFactoryHelper.addRepoMappings(packageBuilder, kwargs, externalRepoName, loc);
-
+        // TODO(adonovan): is this cast safe? Check.
+        String name = (String) kwargs.get("name");
+        WorkspaceFactoryHelper.addMainRepoEntry(packageBuilder, name, thread.getSemantics());
+        WorkspaceFactoryHelper.addRepoMappings(packageBuilder, kwargs, name);
         Rule rule =
             WorkspaceFactoryHelper.createAndAddRepositoryRule(
                 context.getBuilder(),
                 ruleClass,
-                null,
+                /*bindRuleClass=*/ null,
                 WorkspaceFactoryHelper.getFinalKwargs(kwargs),
-                loc,
-                callStack.toString());
+                thread.getSemantics(),
+                thread.getCallStack());
         return rule;
       } catch (InvalidRuleException | NameConflictException | LabelSyntaxException e) {
         throw Starlark.errorf("%s", e.getMessage());
diff --git a/src/main/java/com/google/devtools/build/lib/packages/PackageFactory.java b/src/main/java/com/google/devtools/build/lib/packages/PackageFactory.java
index dc05bdd..88bc70a 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/PackageFactory.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/PackageFactory.java
@@ -365,27 +365,19 @@
       }
       BazelStarlarkContext.from(thread).checkLoadingOrWorkspacePhase(ruleClass.getName());
       try {
-        addRule(getContext(thread), kwargs, thread);
+        RuleFactory.createAndAddRule(
+            getContext(thread),
+            ruleClass,
+            new BuildLangTypedAttributeValuesMap(kwargs),
+            thread.getSemantics(),
+            thread.getCallStack(),
+            new AttributeContainer(ruleClass));
       } catch (RuleFactory.InvalidRuleException | Package.NameConflictException e) {
         throw new EvalException(null, e.getMessage());
       }
       return Starlark.NONE;
     }
 
-    private void addRule(PackageContext context, Map<String, Object> kwargs, StarlarkThread thread)
-        throws RuleFactory.InvalidRuleException, Package.NameConflictException,
-            InterruptedException {
-      BuildLangTypedAttributeValuesMap attributeValues =
-          new BuildLangTypedAttributeValuesMap(kwargs);
-      RuleFactory.createAndAddRule(
-          context,
-          ruleClass,
-          attributeValues,
-          thread.getCallerLocation(),
-          thread,
-          new AttributeContainer(ruleClass));
-    }
-
     @Override
     public RuleClass getRuleClass() {
       return ruleClass;
diff --git a/src/main/java/com/google/devtools/build/lib/packages/Rule.java b/src/main/java/com/google/devtools/build/lib/packages/Rule.java
index 5e2c1b5..4c7f970 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/Rule.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/Rule.java
@@ -74,8 +74,6 @@
 
   private boolean containsErrors;
 
-  private String definitionInformation;
-
   private final Location location;
 
   private final CallStack callstack;
@@ -125,10 +123,6 @@
     this.visibility = visibility;
   }
 
-  void setDefinitionInformation(String info) {
-    this.definitionInformation = info;
-  }
-
   void setAttributeValue(Attribute attribute, Object value, boolean explicit) {
     attributes.setAttributeValue(attribute, value, explicit);
   }
@@ -281,10 +275,6 @@
     return callstack;
   }
 
-  public String getDefinitionInformation() {
-    return definitionInformation;
-  }
-
   public ImplicitOutputsFunction getImplicitOutputsFunction() {
     return implicitOutputsFunction;
   }
diff --git a/src/main/java/com/google/devtools/build/lib/packages/RuleClass.java b/src/main/java/com/google/devtools/build/lib/packages/RuleClass.java
index 5dbfe84..666451c 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/RuleClass.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/RuleClass.java
@@ -641,6 +641,7 @@
             attr("local", Type.BOOLEAN).build());
 
     private String name;
+    private ImmutableList<StarlarkThread.CallStackEntry> callstack = ImmutableList.of();
     private final RuleClassType type;
     private final boolean skylark;
     private boolean skylarkTestable = false;
@@ -830,6 +831,7 @@
 
       return new RuleClass(
           name,
+          callstack,
           key,
           type,
           skylark,
@@ -956,6 +958,12 @@
       return this;
     }
 
+    /** Sets the Starlark call stack associated with this rule class's creation. */
+    public Builder setCallStack(ImmutableList<StarlarkThread.CallStackEntry> callstack) {
+      this.callstack = callstack;
+      return this;
+    }
+
     public Builder setSkylarkTestable() {
       Preconditions.checkState(skylark, "Cannot set skylarkTestable on a non-Starlark rule");
       skylarkTestable = true;
@@ -1398,6 +1406,7 @@
   }
 
   private final String name; // e.g. "cc_library"
+  private final ImmutableList<StarlarkThread.CallStackEntry> callstack; // of call to 'rule'
 
   private final String key; // Just the name for native, label + name for skylark
 
@@ -1539,6 +1548,7 @@
   @VisibleForTesting
   RuleClass(
       String name,
+      ImmutableList<StarlarkThread.CallStackEntry> callstack,
       String key,
       RuleClassType type,
       boolean isSkylark,
@@ -1573,6 +1583,7 @@
       Collection<Attribute> attributes,
       @Nullable BuildSetting buildSetting) {
     this.name = name;
+    this.callstack = callstack;
     this.key = key;
     this.type = type;
     this.isSkylark = isSkylark;
@@ -1678,6 +1689,15 @@
     return name;
   }
 
+  /**
+   * Returns the stack of Starlark active function calls at the moment this rule class was created.
+   * Entries appear outermost first, and exclude the built-in itself ('rule' or 'repository_rule').
+   * Empty for non-Starlark rules.
+   */
+  public ImmutableList<StarlarkThread.CallStackEntry> getCallStack() {
+    return callstack;
+  }
+
   /** Returns the type of rule that this RuleClass represents. Only for use during serialization. */
   public RuleClassType getRuleClassType() {
     return type;
diff --git a/src/main/java/com/google/devtools/build/lib/packages/RuleFactory.java b/src/main/java/com/google/devtools/build/lib/packages/RuleFactory.java
index 6043e28..e080fdf 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/RuleFactory.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/RuleFactory.java
@@ -24,6 +24,7 @@
 import com.google.devtools.build.lib.packages.Attribute.SkylarkComputedDefaultTemplate.CannotPrecomputeDefaultsException;
 import com.google.devtools.build.lib.packages.Package.NameConflictException;
 import com.google.devtools.build.lib.packages.PackageFactory.PackageContext;
+import com.google.devtools.build.lib.syntax.StarlarkSemantics;
 import com.google.devtools.build.lib.syntax.StarlarkThread;
 import java.util.Map;
 import java.util.Set;
@@ -76,8 +77,8 @@
       RuleClass ruleClass,
       BuildLangTypedAttributeValuesMap attributeValues,
       EventHandler eventHandler,
-      Location location,
-      @Nullable StarlarkThread thread,
+      StarlarkSemantics semantics,
+      ImmutableList<StarlarkThread.CallStackEntry> callstack,
       AttributeContainer attributeContainer)
       throws InvalidRuleException, InterruptedException {
     Preconditions.checkNotNull(ruleClass);
@@ -106,21 +107,16 @@
           ruleClass + " cannot be in the WORKSPACE file " + "(used by " + label + ")");
     }
 
-    ImmutableList<StarlarkThread.CallStackEntry> callstack =
-        thread != null ? thread.getCallStack() : ImmutableList.of();
-
     AttributesAndLocation generator =
-        generatorAttributesForMacros(pkgBuilder, attributeValues, callstack, location, label);
+        generatorAttributesForMacros(pkgBuilder, attributeValues, callstack, label);
 
-    if (thread != null) {
-      // The raw stack is of the form [<toplevel>@BUILD:1, macro@lib.bzl:1, cc_library@<builtin>].
-      // If we're recording it (--record_rule_instantiation_callstack),
-      // pop the innermost frame for the rule, since it's obvious.
-      callstack =
-          thread.getSemantics().recordRuleInstantiationCallstack()
-              ? callstack.subList(0, callstack.size() - 1) // pop
-              : ImmutableList.of(); // save space
-    }
+    // The raw stack is of the form [<toplevel>@BUILD:1, macro@lib.bzl:1, cc_library@<builtin>].
+    // If we're recording it (--record_rule_instantiation_callstack),
+    // pop the innermost frame for the rule, since it's obvious.
+    callstack =
+        semantics.recordRuleInstantiationCallstack()
+            ? callstack.subList(0, callstack.size() - 1) // pop
+            : ImmutableList.of(); // save space
 
     try {
       // Examines --incompatible_disable_third_party_license_checking to see if we should check
@@ -129,14 +125,13 @@
       // This flag is overridable by RuleClass.ThirdPartyLicenseEnforcementPolicy (which is checked
       // in RuleClass). This lets Bazel and Blaze migrate away from license logic on independent
       // timelines. See --incompatible_disable_third_party_license_checking comments for details.
-      boolean checkThirdPartyLicenses =
-          thread != null && !thread.getSemantics().incompatibleDisableThirdPartyLicenseChecking();
+      boolean checkThirdPartyLicenses = semantics.incompatibleDisableThirdPartyLicenseChecking();
       return ruleClass.createRule(
           pkgBuilder,
           label,
           generator.attributes,
           eventHandler,
-          generator.location,
+          generator.location, // see b/23974287 for rationale
           callstack,
           attributeContainer,
           checkThirdPartyLicenses);
@@ -157,8 +152,8 @@
    *     a map entry for each non-optional attribute of this class of rule.
    * @param eventHandler a eventHandler on which errors and warnings are reported during rule
    *     creation
-   * @param location the location at which this rule was declared
-   * @param thread the lexical environment of the function call which declared this rule (optional)
+   * @param semantics the Starlark semantics
+   * @param callstack the stack of active calls in the Starlark thread
    * @param attributeContainer the {@link AttributeContainer} the rule will contain
    * @throws InvalidRuleException if the rule could not be constructed for any reason (e.g. no
    *     {@code name} attribute is defined)
@@ -171,8 +166,8 @@
       RuleClass ruleClass,
       BuildLangTypedAttributeValuesMap attributeValues,
       EventHandler eventHandler,
-      Location location,
-      @Nullable StarlarkThread thread,
+      StarlarkSemantics semantics,
+      ImmutableList<StarlarkThread.CallStackEntry> callstack,
       AttributeContainer attributeContainer)
       throws InvalidRuleException, NameConflictException, InterruptedException {
     Rule rule =
@@ -181,8 +176,8 @@
             ruleClass,
             attributeValues,
             eventHandler,
-            location,
-            thread,
+            semantics,
+            callstack,
             attributeContainer);
     pkgBuilder.addRule(rule);
     return rule;
@@ -211,8 +206,8 @@
       PackageContext context,
       RuleClass ruleClass,
       BuildLangTypedAttributeValuesMap attributeValues,
-      Location loc,
-      @Nullable StarlarkThread thread,
+      StarlarkSemantics semantics,
+      ImmutableList<StarlarkThread.CallStackEntry> callstack,
       AttributeContainer attributeContainer)
       throws InvalidRuleException, NameConflictException, InterruptedException {
     return createAndAddRule(
@@ -220,8 +215,8 @@
         ruleClass,
         attributeValues,
         context.eventHandler,
-        loc,
-        thread,
+        semantics,
+        callstack,
         attributeContainer);
   }
 
@@ -319,8 +314,11 @@
       Package.Builder pkgBuilder,
       BuildLangTypedAttributeValuesMap args,
       ImmutableList<StarlarkThread.CallStackEntry> stack,
-      Location location,
       Label label) {
+    // For a callstack [BUILD <toplevel>, .bzl <function>, <rule>],
+    // location is that of the caller of 'rule' (the .bzl function).
+    Location location = stack.size() < 2 ? Location.BUILTIN : stack.get(stack.size() - 2).location;
+
     boolean hasName = args.containsAttributeNamed("generator_name");
     boolean hasFunc = args.containsAttributeNamed("generator_function");
     // TODO(bazel-team): resolve cases in our code where hasName && !hasFunc, or hasFunc && !hasName
@@ -336,33 +334,34 @@
     if (stack.size() < 2 || !stack.get(1).location.file().endsWith(".bzl")) {
       return new AttributesAndLocation(args, location); // macro is not a Starlark function
     }
-    // TODO(adonovan): is it correct that we clobber the location used by
-    // BuildLangTypedAttributeValuesMap?
-    location = stack.get(0).location;
+    Location generatorLocation = stack.get(0).location; // location of call to generator
     String generatorFunction = stack.get(1).name;
     ImmutableMap.Builder<String, Object> builder = ImmutableMap.builder();
     for (Map.Entry<String, Object> attributeAccessor : args.getAttributeAccessors()) {
       String attributeName = args.getName(attributeAccessor);
       builder.put(attributeName, args.getValue(attributeAccessor));
     }
-    String generatorName = pkgBuilder.getGeneratorNameByLocation().get(location);
+    String generatorName = pkgBuilder.getGeneratorNameByLocation().get(generatorLocation);
     if (generatorName == null) {
       generatorName = (String) args.getAttributeValue("name");
     }
     builder.put("generator_name", generatorName);
     builder.put("generator_function", generatorFunction);
-    String relativePath = maybeGetRelativeLocation(location, label);
+    String relativePath = maybeGetRelativeLocation(generatorLocation, label);
     if (relativePath != null) {
       builder.put("generator_location", relativePath);
     }
 
     try {
-      return new AttributesAndLocation(
-          new BuildLangTypedAttributeValuesMap(builder.build()), location);
-    } catch (IllegalArgumentException ex) {
+      args = new BuildLangTypedAttributeValuesMap(builder.build());
+    } catch (IllegalArgumentException unused) {
       // We just fall back to the default case and swallow any messages.
-      return new AttributesAndLocation(args, location);
     }
+
+    // TODO(adonovan): is it appropriate to use generatorLocation as the rule's main location?
+    // Or would 'location' (the immediate call) be more informative? When there are errors, the
+    // location of the toplevel call of the generator may be quite unrelated to the error message.
+    return new AttributesAndLocation(args, generatorLocation);
   }
 
   /**
diff --git a/src/main/java/com/google/devtools/build/lib/packages/WorkspaceFactory.java b/src/main/java/com/google/devtools/build/lib/packages/WorkspaceFactory.java
index 708eb65..132a15b 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/WorkspaceFactory.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/WorkspaceFactory.java
@@ -23,7 +23,6 @@
 import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.cmdline.RepositoryName;
 import com.google.devtools.build.lib.events.Event;
-import com.google.devtools.build.lib.events.Location;
 import com.google.devtools.build.lib.events.NullEventHandler;
 import com.google.devtools.build.lib.events.StoredEventHandler;
 import com.google.devtools.build.lib.packages.Package.NameConflictException;
@@ -289,19 +288,16 @@
           if (!allowOverride
               && externalRepoName != null
               && builder.getTarget(externalRepoName) != null) {
-            throw new EvalException(
-                null,
-                "Cannot redefine repository after any load statement in the WORKSPACE file"
-                    + " (for repository '"
-                    + kwargs.get("name")
-                    + "')");
+            throw Starlark.errorf(
+                "Cannot redefine repository after any load statement in the WORKSPACE file (for"
+                    + " repository '%s')",
+                externalRepoName);
           }
           // Add an entry in every repository from @<mainRepoName> to "@" to avoid treating
           // @<mainRepoName> as a separate repository. This will be overridden if the main
           // repository has a repo_mapping entry from <mainRepoName> to something.
           WorkspaceFactoryHelper.addMainRepoEntry(builder, externalRepoName, thread.getSemantics());
-          Location loc = thread.getCallerLocation();
-          WorkspaceFactoryHelper.addRepoMappings(builder, kwargs, externalRepoName, loc);
+          WorkspaceFactoryHelper.addRepoMappings(builder, kwargs, externalRepoName);
           RuleClass ruleClass = ruleFactory.getRuleClass(ruleClassName);
           RuleClass bindRuleClass = ruleFactory.getRuleClass("bind");
           Rule rule =
@@ -310,7 +306,8 @@
                   ruleClass,
                   bindRuleClass,
                   WorkspaceFactoryHelper.getFinalKwargs(kwargs),
-                  loc);
+                  thread.getSemantics(),
+                  thread.getCallStack());
           if (!WorkspaceGlobals.isLegalWorkspaceName(rule.getName())) {
             throw new EvalException(
                 null,
diff --git a/src/main/java/com/google/devtools/build/lib/packages/WorkspaceFactoryHelper.java b/src/main/java/com/google/devtools/build/lib/packages/WorkspaceFactoryHelper.java
index 157bbd3..412ea2d 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/WorkspaceFactoryHelper.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/WorkspaceFactoryHelper.java
@@ -17,17 +17,18 @@
 import com.google.common.base.Preconditions;
 import com.google.common.base.Strings;
 import com.google.common.base.Verify;
+import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Maps;
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.cmdline.RepositoryName;
-import com.google.devtools.build.lib.events.Location;
 import com.google.devtools.build.lib.events.StoredEventHandler;
 import com.google.devtools.build.lib.packages.RuleFactory.BuildLangTypedAttributeValuesMap;
-import com.google.devtools.build.lib.syntax.Dict;
 import com.google.devtools.build.lib.syntax.EvalException;
+import com.google.devtools.build.lib.syntax.SkylarkType;
 import com.google.devtools.build.lib.syntax.StarlarkSemantics;
+import com.google.devtools.build.lib.syntax.StarlarkThread;
 import java.util.Map;
 import java.util.stream.Collectors;
 
@@ -39,22 +40,10 @@
       RuleClass ruleClass,
       RuleClass bindRuleClass,
       Map<String, Object> kwargs,
-      Location loc)
+      StarlarkSemantics semantics,
+      ImmutableList<StarlarkThread.CallStackEntry> callstack)
       throws RuleFactory.InvalidRuleException, Package.NameConflictException, LabelSyntaxException,
           InterruptedException {
-    return createAndAddRepositoryRule(pkg, ruleClass, bindRuleClass, kwargs, loc, null);
-  }
-
-  public static Rule createAndAddRepositoryRule(
-      Package.Builder pkg,
-      RuleClass ruleClass,
-      RuleClass bindRuleClass,
-      Map<String, Object> kwargs,
-      Location loc,
-      String definitionInfo)
-      throws RuleFactory.InvalidRuleException, Package.NameConflictException, LabelSyntaxException,
-          InterruptedException {
-
     StoredEventHandler eventHandler = new StoredEventHandler();
     BuildLangTypedAttributeValuesMap attributeValues = new BuildLangTypedAttributeValuesMap(kwargs);
     Rule rule =
@@ -63,8 +52,8 @@
             ruleClass,
             attributeValues,
             eventHandler,
-            loc,
-            /* thread= */ null,
+            semantics,
+            callstack,
             new AttributeContainer(ruleClass));
     pkg.addEvents(eventHandler.getEvents());
     pkg.addPosts(eventHandler.getPosts());
@@ -77,10 +66,10 @@
           bindRuleClass,
           nameLabel,
           entry.getValue(),
-          rule.getLocation(),
+          semantics,
+          callstack,
           new AttributeContainer(bindRuleClass));
     }
-    rule.setDefinitionInformation(definitionInfo);
     return rule;
   }
 
@@ -124,28 +113,18 @@
   /**
    * Processes {@code repo_mapping} attribute and populates the package builder with the mappings.
    *
-   * @throws EvalException if {@code repo_mapping} is present in kwargs but is not a {@link Dict}
+   * @throws EvalException if {@code repo_mapping} is present in kwargs but is not a
+   *     string-to-string dict.
    */
   public static void addRepoMappings(
-      Package.Builder builder,
-      Map<String, Object> kwargs,
-      String externalRepoName,
-      Location location)
+      Package.Builder builder, Map<String, Object> kwargs, String externalRepoName)
       throws EvalException, LabelSyntaxException {
-
-    if (kwargs.containsKey("repo_mapping")) {
-      if (!(kwargs.get("repo_mapping") instanceof Dict)) {
-        throw new EvalException(
-            location,
-            "Invalid value for 'repo_mapping': '"
-                + kwargs.get("repo_mapping")
-                + "'. Value must be a dict.");
-      }
-      @SuppressWarnings("unchecked")
-      Map<String, String> map = (Map<String, String>) kwargs.get("repo_mapping");
+    Object repoMapping = kwargs.get("repo_mapping");
+    if (repoMapping != null) {
+      Map<String, String> map =
+          SkylarkType.castMap(repoMapping, String.class, String.class, "repo_mapping");
       for (Map.Entry<String, String> e : map.entrySet()) {
-        // Create repository names with validation, LabelSyntaxException is thrown is the name
-        // is not valid.
+        // Create repository names with validation; may throw LabelSyntaxException.
         builder.addRepositoryMappingEntry(
             RepositoryName.create("@" + externalRepoName),
             RepositoryName.create(e.getKey()),
@@ -159,7 +138,8 @@
       RuleClass bindRuleClass,
       Label virtual,
       Label actual,
-      Location location,
+      StarlarkSemantics semantics,
+      ImmutableList<StarlarkThread.CallStackEntry> callstack,
       AttributeContainer attributeContainer)
       throws RuleFactory.InvalidRuleException, Package.NameConflictException, InterruptedException {
 
@@ -175,13 +155,7 @@
         new BuildLangTypedAttributeValuesMap(attributes);
     Rule rule =
         RuleFactory.createRule(
-            pkg,
-            bindRuleClass,
-            attributeValues,
-            handler,
-            location,
-            /* thread= */ null,
-            attributeContainer);
+            pkg, bindRuleClass, attributeValues, handler, semantics, callstack, attributeContainer);
     overwriteRule(pkg, rule);
     rule.setVisibility(ConstantRuleVisibility.PUBLIC);
   }
diff --git a/src/main/java/com/google/devtools/build/lib/packages/WorkspaceGlobals.java b/src/main/java/com/google/devtools/build/lib/packages/WorkspaceGlobals.java
index de1af56..252de68 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/WorkspaceGlobals.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/WorkspaceGlobals.java
@@ -72,40 +72,42 @@
       Dict<?, ?> managedDirectories, // <String, Object>
       StarlarkThread thread)
       throws EvalException, InterruptedException {
-    if (allowOverride) {
-      if (!isLegalWorkspaceName(name)) {
-        throw Starlark.errorf("%s is not a legal workspace name", name);
-      }
-      String errorMessage = LabelValidator.validateTargetName(name);
-      if (errorMessage != null) {
-        throw Starlark.errorf("%s", errorMessage);
-      }
-      PackageFactory.getContext(thread).pkgBuilder.setWorkspaceName(name);
-      Package.Builder builder = PackageFactory.getContext(thread).pkgBuilder;
-      RuleClass localRepositoryRuleClass = ruleFactory.getRuleClass("local_repository");
-      RuleClass bindRuleClass = ruleFactory.getRuleClass("bind");
-      Map<String, Object> kwargs = ImmutableMap.<String, Object>of("name", name, "path", ".");
-      try {
-        // This effectively adds a "local_repository(name = "<ws>", path = ".")"
-        // definition to the WORKSPACE file.
-        WorkspaceFactoryHelper.createAndAddRepositoryRule(
-            builder, localRepositoryRuleClass, bindRuleClass, kwargs, thread.getCallerLocation());
-      } catch (InvalidRuleException | NameConflictException | LabelSyntaxException e) {
-        throw Starlark.errorf("%s", e.getMessage());
-      }
-      // Add entry in repository map from "@name" --> "@" to avoid issue where bazel
-      // treats references to @name as a separate external repo
-      builder.addRepositoryMappingEntry(
-          RepositoryName.MAIN,
-          RepositoryName.createFromValidStrippedName(name),
-          RepositoryName.MAIN);
-      parseManagedDirectories(
-          managedDirectories.getContents(String.class, Object.class, "managed_directories"));
-      return NONE;
-    } else {
+    if (!allowOverride) {
       throw Starlark.errorf(
           "workspace() function should be used only at the top of the WORKSPACE file");
     }
+    if (!isLegalWorkspaceName(name)) {
+      throw Starlark.errorf("%s is not a legal workspace name", name);
+    }
+    String errorMessage = LabelValidator.validateTargetName(name);
+    if (errorMessage != null) {
+      throw Starlark.errorf("%s", errorMessage);
+    }
+    PackageFactory.getContext(thread).pkgBuilder.setWorkspaceName(name);
+    Package.Builder builder = PackageFactory.getContext(thread).pkgBuilder;
+    RuleClass localRepositoryRuleClass = ruleFactory.getRuleClass("local_repository");
+    RuleClass bindRuleClass = ruleFactory.getRuleClass("bind");
+    Map<String, Object> kwargs = ImmutableMap.<String, Object>of("name", name, "path", ".");
+    try {
+      // This effectively adds a "local_repository(name = "<ws>", path = ".")"
+      // definition to the WORKSPACE file.
+      WorkspaceFactoryHelper.createAndAddRepositoryRule(
+          builder,
+          localRepositoryRuleClass,
+          bindRuleClass,
+          kwargs,
+          thread.getSemantics(),
+          thread.getCallStack());
+    } catch (InvalidRuleException | NameConflictException | LabelSyntaxException e) {
+      throw Starlark.errorf("%s", e.getMessage());
+    }
+    // Add entry in repository map from "@name" --> "@" to avoid issue where bazel
+    // treats references to @name as a separate external repo
+    builder.addRepositoryMappingEntry(
+        RepositoryName.MAIN, RepositoryName.createFromValidStrippedName(name), RepositoryName.MAIN);
+    parseManagedDirectories(
+        managedDirectories.getContents(String.class, Object.class, "managed_directories"));
+    return NONE;
   }
 
   @Override
@@ -281,11 +283,10 @@
           ruleClass,
           nameLabel,
           actual == NONE ? null : Label.parseAbsolute((String) actual, ImmutableMap.of()),
-          thread.getCallerLocation(),
+          thread.getSemantics(),
+          thread.getCallStack(),
           new AttributeContainer(ruleClass));
-    } catch (RuleFactory.InvalidRuleException
-        | Package.NameConflictException
-        | LabelSyntaxException e) {
+    } catch (InvalidRuleException | Package.NameConflictException | LabelSyntaxException e) {
       throw Starlark.errorf("%s", e.getMessage());
     }
 
diff --git a/src/main/java/com/google/devtools/build/lib/query2/query/output/BuildOutputFormatter.java b/src/main/java/com/google/devtools/build/lib/query2/query/output/BuildOutputFormatter.java
index 36a5bdc..636d30e 100644
--- a/src/main/java/com/google/devtools/build/lib/query2/query/output/BuildOutputFormatter.java
+++ b/src/main/java/com/google/devtools/build/lib/query2/query/output/BuildOutputFormatter.java
@@ -139,14 +139,29 @@
       writer.append(")").append(lineTerm);
 
       // Display the instantiation stack, if any.
+      appendStack(
+          String.format("# Rule %s instantiated at (most recent call last):", rule.getName()),
+          rule.getCallStack().toList());
+
+      // Display the stack of the rule class definition, if any.
+      appendStack(
+          String.format("# Rule %s defined at (most recent call last):", rule.getRuleClass()),
+          rule.getRuleClassObject().getCallStack());
+
+      // TODO(adonovan): also list inputs and outputs of the rule.
+
+      writer.append(lineTerm);
+    }
+
+    private void appendStack(String title, List<StarlarkThread.CallStackEntry> stack)
+        throws IOException {
       // For readability, ensure columns line up.
       int maxLocLen = 0;
-      List<StarlarkThread.CallStackEntry> stack = rule.getCallStack().toList().reverse();
       for (StarlarkThread.CallStackEntry fr : stack) {
         maxLocLen = Math.max(maxLocLen, fr.location.toString().length());
       }
       if (maxLocLen > 0) {
-        writer.append("# Instantiation stack:\n");
+        writer.append(title).append(lineTerm);
         for (StarlarkThread.CallStackEntry fr : stack) {
           String loc = fr.location.toString(); // TODO(b/151151653): display root-relative
           // Java's String.format doesn't support
@@ -155,14 +170,9 @@
           for (int i = loc.length(); i < maxLocLen; i++) {
             writer.append(' ');
           }
-          writer.append(" called from ").append(fr.name).append("\n");
+          writer.append(" in ").append(fr.name).append(lineTerm);
         }
       }
-
-      // TODO(adonovan): also record and show creation stack for rule.getRuleClassObject(),
-      // and list inputs and outputs of the rule.
-
-      writer.append(lineTerm);
     }
 
     /** Outputs the given attribute value BUILD-style. Does not support selects. */
diff --git a/src/main/java/com/google/devtools/build/lib/rules/repository/WorkspaceAttributeMapper.java b/src/main/java/com/google/devtools/build/lib/rules/repository/WorkspaceAttributeMapper.java
index 432360a..61c5593 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/repository/WorkspaceAttributeMapper.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/repository/WorkspaceAttributeMapper.java
@@ -22,7 +22,6 @@
 import com.google.devtools.build.lib.packages.Rule;
 import com.google.devtools.build.lib.packages.Type;
 import com.google.devtools.build.lib.syntax.EvalException;
-import com.google.devtools.build.lib.vfs.PathFragment;
 import javax.annotation.Nullable;
 
 /**
@@ -62,15 +61,12 @@
   public Object getObject(String attributeName) throws EvalException {
     Object value = rule.getAttributeContainer().getAttr(checkNotNull(attributeName));
     if (value instanceof SelectorList) {
-      String message;
-      // Is there a basename function for strings?
-      String base = PathFragment.create(rule.getLocation().file()).getBaseName();
-      if (WorkspaceFileHelper.matchWorkspaceFileName(base)) {
-        message = "select() cannot be used in WORKSPACE files";
-      } else {
-        message = "select() cannot be used in macros called from WORKSPACE files";
-      }
-      throw new EvalException(rule.getLocation(), message);
+      throw new EvalException(
+          rule.getLocation(),
+          String.format(
+              "got value of type 'select' for attribute '%s' of %s rule '%s'; select may not be "
+                  + "used in repository rules",
+              attributeName, rule.getRuleClass(), rule.getName()));
     }
     return value;
   }
diff --git a/src/test/java/com/google/devtools/build/lib/bazel/repository/skylark/SkylarkRepositoryContextTest.java b/src/test/java/com/google/devtools/build/lib/bazel/repository/skylark/SkylarkRepositoryContextTest.java
index 11c4116..331a0e0 100644
--- a/src/test/java/com/google/devtools/build/lib/bazel/repository/skylark/SkylarkRepositoryContextTest.java
+++ b/src/test/java/com/google/devtools/build/lib/bazel/repository/skylark/SkylarkRepositoryContextTest.java
@@ -113,6 +113,15 @@
     }
   }
 
+  private static final ImmutableList<StarlarkThread.CallStackEntry> DUMMY_STACK =
+      ImmutableList.of(
+          new StarlarkThread.CallStackEntry( //
+              "<toplevel>", Location.fromFileLineColumn("BUILD", 10, 1)),
+          new StarlarkThread.CallStackEntry( //
+              "foo", Location.fromFileLineColumn("foo.bzl", 42, 1)),
+          new StarlarkThread.CallStackEntry( //
+              "myrule", Location.fromFileLineColumn("bar.bzl", 30, 6)));
+
   protected void setUpContextForRule(
       Map<String, Object> kwargs,
       ImmutableSet<PathFragment> ignoredPathFragments,
@@ -129,7 +138,12 @@
     ExtendedEventHandler listener = Mockito.mock(ExtendedEventHandler.class);
     Rule rule =
         WorkspaceFactoryHelper.createAndAddRepositoryRule(
-            packageBuilder, buildRuleClass(attributes), null, kwargs, Location.BUILTIN);
+            packageBuilder,
+            buildRuleClass(attributes),
+            null,
+            kwargs,
+            starlarkSemantics,
+            DUMMY_STACK);
     DownloadManager downloader = Mockito.mock(DownloadManager.class);
     SkyFunction.Environment environment = Mockito.mock(SkyFunction.Environment.class);
     when(environment.getListener()).thenReturn(listener);
diff --git a/src/test/java/com/google/devtools/build/lib/packages/RuleClassTest.java b/src/test/java/com/google/devtools/build/lib/packages/RuleClassTest.java
index 8952ceb..5a45849 100644
--- a/src/test/java/com/google/devtools/build/lib/packages/RuleClassTest.java
+++ b/src/test/java/com/google/devtools/build/lib/packages/RuleClassTest.java
@@ -92,6 +92,13 @@
             }
           };
 
+  private static final ImmutableList<StarlarkThread.CallStackEntry> DUMMY_STACK =
+      ImmutableList.of(
+          new StarlarkThread.CallStackEntry(
+              "<toplevel>", Location.fromFileLineColumn("BUILD", 10, 1)),
+          new StarlarkThread.CallStackEntry("bar", Location.fromFileLineColumn("bar.bzl", 42, 1)),
+          new StarlarkThread.CallStackEntry("rule", Location.BUILTIN));
+
   private static final class DummyFragment extends BuildConfiguration.Fragment {}
 
   private static final ImmutableList<StarlarkThread.CallStackEntry> NO_STACK = ImmutableList.of();
@@ -896,7 +903,8 @@
             : ruleDefinitionStarlarkThread.getTransitiveContentHashCode();
     return new RuleClass(
         name,
-        name,
+        DUMMY_STACK,
+        /*key=*/ name,
         RuleClassType.NORMAL,
         /*isSkylark=*/ skylarkExecutable,
         /*skylarkTestable=*/ false,
diff --git a/src/test/java/com/google/devtools/build/lib/packages/RuleFactoryTest.java b/src/test/java/com/google/devtools/build/lib/packages/RuleFactoryTest.java
index 76b7455..3a2cf37 100644
--- a/src/test/java/com/google/devtools/build/lib/packages/RuleFactoryTest.java
+++ b/src/test/java/com/google/devtools/build/lib/packages/RuleFactoryTest.java
@@ -17,6 +17,7 @@
 import static com.google.common.truth.Truth.assertWithMessage;
 import static com.google.devtools.build.lib.testutil.MoreAsserts.assertThrows;
 
+import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Lists;
 import com.google.common.collect.Sets;
@@ -30,6 +31,7 @@
 import com.google.devtools.build.lib.packages.RuleFactory.BuildLangTypedAttributeValuesMap;
 import com.google.devtools.build.lib.packages.util.PackageLoadingTestCase;
 import com.google.devtools.build.lib.syntax.StarlarkSemantics;
+import com.google.devtools.build.lib.syntax.StarlarkThread;
 import com.google.devtools.build.lib.testutil.TestRuleClassProvider;
 import com.google.devtools.build.lib.vfs.Path;
 import com.google.devtools.build.lib.vfs.RootedPath;
@@ -45,7 +47,13 @@
   private ConfiguredRuleClassProvider provider = TestRuleClassProvider.getRuleClassProvider();
   private final RuleFactory ruleFactory = new RuleFactory(provider);
 
-  private static final Location DUMMY_LOCATION = Location.fromFileLineColumn("dummy", 42, 1);
+  private static final ImmutableList<StarlarkThread.CallStackEntry> DUMMY_STACK =
+      ImmutableList.of(
+          new StarlarkThread.CallStackEntry(
+              "<toplevel>", Location.fromFileLineColumn("BUILD", 42, 1)),
+          new StarlarkThread.CallStackEntry("foo", Location.fromFileLineColumn("foo.bzl", 10, 1)),
+          new StarlarkThread.CallStackEntry(
+              "myrule", Location.fromFileLineColumn("bar.bzl", 30, 6)));
 
   @Test
   public void testCreateRule() throws Exception {
@@ -69,8 +77,8 @@
             ruleClass,
             new BuildLangTypedAttributeValuesMap(attributeValues),
             new Reporter(new EventBus()),
-            DUMMY_LOCATION,
-            /*thread=*/ null,
+            StarlarkSemantics.DEFAULT_SEMANTICS,
+            DUMMY_STACK,
             new AttributeContainer(ruleClass));
 
     assertThat(rule.getAssociatedRule()).isSameInstanceAs(rule);
@@ -87,6 +95,11 @@
 
     assertThat(rule.getRuleClass()).isEqualTo("cc_library");
     assertThat(rule.getTargetKind()).isEqualTo("cc_library rule");
+    // The rule reports the location of the outermost call (aka generator), in the BUILD file.
+    // Thie behavior was added to fix b/23974287, but it loses informtion and is redundant
+    // w.r.t. generator_location. A better fix to that issue would be to keep rule.location as
+    // the innermost call, and to report the entire call stack at the first error for the rule.
+    assertThat(rule.getLocation().file()).isEqualTo("BUILD");
     assertThat(rule.getLocation().line()).isEqualTo(42);
     assertThat(rule.getLocation().column()).isEqualTo(1);
     assertThat(rule.containsErrors()).isFalse();
@@ -124,8 +137,8 @@
             ruleClass,
             new BuildLangTypedAttributeValuesMap(attributeValues),
             new Reporter(new EventBus()),
-            Location.fromFile(myPkgPath.toString()),
-            /*thread=*/ null,
+            StarlarkSemantics.DEFAULT_SEMANTICS,
+            DUMMY_STACK,
             new AttributeContainer(ruleClass));
     assertThat(rule.containsErrors()).isFalse();
   }
@@ -155,8 +168,8 @@
                     ruleClass,
                     new BuildLangTypedAttributeValuesMap(attributeValues),
                     new Reporter(new EventBus()),
-                    DUMMY_LOCATION,
-                    /*thread=*/ null,
+                    StarlarkSemantics.DEFAULT_SEMANTICS,
+                    DUMMY_STACK,
                     new AttributeContainer(ruleClass)));
     assertThat(e).hasMessageThat().contains("must be in the WORKSPACE file");
   }
@@ -186,8 +199,8 @@
                     ruleClass,
                     new BuildLangTypedAttributeValuesMap(attributeValues),
                     new Reporter(new EventBus()),
-                    Location.fromFileLineColumn(myPkgPath.toString(), 42, 1),
-                    /*thread=*/ null,
+                    StarlarkSemantics.DEFAULT_SEMANTICS,
+                    DUMMY_STACK,
                     new AttributeContainer(ruleClass)));
     assertThat(e).hasMessageThat().contains("cannot be in the WORKSPACE file");
   }
@@ -229,8 +242,8 @@
                     ruleClass,
                     new BuildLangTypedAttributeValuesMap(attributeValues),
                     new Reporter(new EventBus()),
-                    Location.fromFileLineColumn(myPkgPath.toString(), 42, 1),
-                    /*thread=*/ null,
+                    StarlarkSemantics.DEFAULT_SEMANTICS,
+                    DUMMY_STACK,
                     new AttributeContainer(ruleClass)));
     assertWithMessage(e.getMessage())
         .that(e.getMessage().contains("output file name can't be equal '.'"))
diff --git a/src/test/java/com/google/devtools/build/lib/packages/WorkspaceFactoryTest.java b/src/test/java/com/google/devtools/build/lib/packages/WorkspaceFactoryTest.java
index 7cdd3c8..7aaa3e8 100644
--- a/src/test/java/com/google/devtools/build/lib/packages/WorkspaceFactoryTest.java
+++ b/src/test/java/com/google/devtools/build/lib/packages/WorkspaceFactoryTest.java
@@ -173,24 +173,18 @@
   }
 
   @Test
-  public void testMappingsNotAMap() throws Exception {
-    helper.parse(
-        "local_repository(",
-        "    name = 'foo',",
-        "    path = '/foo',",
-        "    repo_mapping = 1",
-        ")");
+  public void testRepoMappingNotAStringStringDict() throws Exception {
+    helper.parse("local_repository(name='foo', path='/foo', repo_mapping=1)");
     assertThat(helper.getParserError())
-        .contains("Invalid value for 'repo_mapping': '1'. Value must be a dict.");
+        .contains("expected a dictionary for 'repo_mapping' but got 'int' instead");
 
-    helper.parse(
-        "local_repository(",
-        "    name = 'foo',",
-        "    path = '/foo',",
-        "    repo_mapping = 'hello'",
-        ")");
+    helper.parse("local_repository(name='foo', path='/foo', repo_mapping='hello')");
     assertThat(helper.getParserError())
-        .contains("Invalid value for 'repo_mapping': 'hello'. Value must be a dict.");
+        .contains("expected a dictionary for 'repo_mapping' but got 'string' instead");
+
+    helper.parse("local_repository(name='foo', path='/foo', repo_mapping={1: 1})");
+    assertThat(helper.getParserError())
+        .contains("expected <String, String> type for 'repo_mapping' but got <int, int> instead");
   }
 
   @Test
diff --git a/src/test/shell/bazel/external_integration_test.sh b/src/test/shell/bazel/external_integration_test.sh
index 1a9d083..43532a1 100755
--- a/src/test/shell/bazel/external_integration_test.sh
+++ b/src/test/shell/bazel/external_integration_test.sh
@@ -2238,12 +2238,17 @@
     )
 EOF
 
-  bazel build @foo//... > "${TEST_log}" 2>&1 && fail "expected failure"
+  bazel build --record_rule_instantiation_callstack @foo//... > "${TEST_log}" 2>&1 && fail "expected failure"
+  inplace-sed -e "s?$WRKDIR/?WRKDIR/?g" -e "s?$TEST_TMPDIR/?TEST_TMPDIR/?g" "${TEST_log}"
+
   expect_log 'error.*repository.*foo'
   expect_log '@bar//:foo.build'
-  expect_log 'path/to/main/foo.bzl'
-  expect_log 'path/to/main/repos.bzl'
-  expect_log 'path/to/main/WORKSPACE'
+  expect_log "Repository foo instantiated at:"
+  expect_log "  WRKDIR/path/to/main/WORKSPACE:"
+  expect_log "  WRKDIR/path/to/main/repos.bzl:5"
+  expect_log "  WRKDIR/path/to/main/foo.bzl:4"
+  expect_log "Repository rule http_archive defined at:"
+  expect_log "  TEST_TMPDIR/.*/external/bazel_tools/tools/build_defs/repo/http.bzl:"
 }
 
 function test_circular_definition_reported() {
@@ -2309,7 +2314,8 @@
 EOF
   touch BUILD
 
-  bazel build //... > "${TEST_log}" 2>&1 && fail "expected failure" || :
+  bazel build --record_rule_instantiation_callstack //... > "${TEST_log}" 2>&1 && fail "expected failure" || :
+  inplace-sed -e 's?$(pwd)/?PWD/?g' "${TEST_log}"
 
   expect_not_log '[iI]nternal [eE]rror'
   expect_not_log 'IllegalStateException'
@@ -2360,13 +2366,17 @@
 load("@data//:value.bzl", "value")
 EOF
 
-  bazel build //... > "${TEST_log}" 2>&1 && fail "expected failure" || :
+  # TODO(adonovan): add a test that the error message contains a hint to set the flag if unset.
+  bazel build --record_rule_instantiation_callstack //... > "${TEST_log}" 2>&1 && fail "expected failure" || :
+  inplace-sed -e 's?$(pwd)/?PWD/?g' "${TEST_log}"
 
-  expect_log "add.*this_repo_is_missing.*WORKSPACE"
+  expect_log "you have to add.*this_repo_is_missing.*WORKSPACE"
   # Also verify that the repository class and its definition is reported, to
   # help finding out where the implict dependency comes from.
-  expect_log 'data.*is.*data_repo'
-  expect_log 'data_repo.*main/withimplicit.bzl:6'
+  expect_log "Repository data instantiated at:"
+  expect_log ".../WORKSPACE:47"
+  expect_log "Repository rule data_repo defined at:"
+  expect_log ".../withimplicit.bzl:6"
 }
 
 function test_overwrite_existing_workspace_build() {
diff --git a/src/test/shell/bazel/workspace_resolved_test.sh b/src/test/shell/bazel/workspace_resolved_test.sh
index 0ea10a4..12bf50b 100755
--- a/src/test/shell/bazel/workspace_resolved_test.sh
+++ b/src/test/shell/bazel/workspace_resolved_test.sh
@@ -52,14 +52,18 @@
 EOF
 
   bazel clean --expunge
-  bazel build --experimental_repository_resolved_file=../repo.bzl @ext//... \
+  bazel build --experimental_repository_resolved_file=../repo.bzl --record_rule_instantiation_callstack @ext//... \
         > "${TEST_log}" 2>&1 || fail "Expected success"
+  inplace-sed -e "s?$(pwd)?PWD?g" "$TEST_log"
   bazel shutdown
 
   # We expect the additional argument to be reported to the user...
   expect_log 'extra_arg.*foobar'
-  # ...as well as the location of the definition.
-  expect_log 'fetchrepo/WORKSPACE:2'
+  # ...as well as the location of the rule instantiation and definition.
+  expect_log 'Repository ext instantiated at:'
+  expect_log '  PWD/WORKSPACE:2:'
+  expect_log 'Repository rule trivial_rule defined at:'
+  expect_log '  PWD/rule.bzl:5:'
 
   # Verify that bazel can read the generated repo.bzl file and that it contains
   # the expected information
@@ -1177,6 +1181,7 @@
 EOF
 
   bazel sync --distdir=${EXTREPODIR}/test_WORKSPACE/distdir \
+        --record_rule_instantiation_callstack \
         --experimental_repository_resolved_file=resolved.bzl
 
   echo; cat resolved.bzl; echo
@@ -1199,13 +1204,16 @@
       return repo["definition_information"]
 EOF
 
-  bazel build //:ext_def
+  bazel build --record_rule_instantiation_callstack //:ext_def
 
   cat `bazel info bazel-genfiles`/ext_def.txt > "${TEST_log}"
-
-  expect_log "WORKSPACE:3"
-  expect_log "first/path/foo.bzl:4"
-  expect_log "another/directory/bar.bzl:4"
+  inplace-sed -e "s?$(pwd)/?PWD/?g" -e "s?$TEST_TMPDIR/?TEST_TMPDIR/?g" "${TEST_log}"
+  expect_log "Repository ext instantiated at:"
+  expect_log "  PWD/WORKSPACE:3"
+  expect_log "  PWD/first/path/foo.bzl:4"
+  expect_log "  PWD/another/directory/bar.bzl:4"
+  expect_log "Repository rule http_archive defined at:"
+  expect_log "  TEST_TMPDIR/.*/external/bazel_tools/tools/build_defs/repo/http.bzl:"
 }
 
 run_suite "workspace_resolved_test tests"
diff --git a/src/test/shell/bazel/workspace_test.sh b/src/test/shell/bazel/workspace_test.sh
index 3741027..0c33210 100755
--- a/src/test/shell/bazel/workspace_test.sh
+++ b/src/test/shell/bazel/workspace_test.sh
@@ -132,7 +132,7 @@
 )
 EOF
   bazel build @foo//... &> $TEST_log && fail "Failure expected" || true
-  expect_log "select() cannot be used in WORKSPACE files"
+  expect_log "got value of type 'select' for attribute 'build_file' of new_local_repository rule 'foo'; select may not be used in repository rules"
 }
 
 function test_macro_select() {
@@ -153,7 +153,7 @@
 EOF
 
   bazel build @foo//... &> $TEST_log && fail "Failure expected" || true
-  expect_log "select() cannot be used in macros called from WORKSPACE files"
+  expect_log "got value of type 'select' for attribute 'build_file' of new_local_repository rule 'foo'"
 }
 
 function test_clean() {
diff --git a/src/test/shell/integration_test_setup.sh b/src/test/shell/integration_test_setup.sh
index 1b68adc..bbf862e 100755
--- a/src/test/shell/integration_test_setup.sh
+++ b/src/test/shell/integration_test_setup.sh
@@ -42,3 +42,14 @@
   # Load the test environment
   source "$DIR/testenv.sh" || print_message_and_exit "testenv.sh not found!"
 fi
+
+# inplace-sed: a version of sed -i that actually works on Linux and Darwin.
+# https://unix.stackexchange.com/questions/92895
+# https://stackoverflow.com/questions/5694228
+function inplace-sed() {
+  if [ $(uname) = "Darwin" ]; then
+    sed -i "" "$@"
+  else
+    sed -i "$@"
+  fi
+}