Pass through information about package lookup failure into import lookup. This fixes 'Misleading error message "file must have a corresponding package"' '#7094. PiperOrigin-RevId: 235806611

diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/ContainingPackageLookupFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/ContainingPackageLookupFunction.java
index f3ca988..0cdc9e8 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/ContainingPackageLookupFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/ContainingPackageLookupFunction.java

@@ -14,6 +14,7 @@
 package com.google.devtools.build.lib.skyframe;
 
 import com.google.devtools.build.lib.cmdline.PackageIdentifier;
+import com.google.devtools.build.lib.skyframe.PackageLookupValue.ErrorReason;
 import com.google.devtools.build.lib.skyframe.PackageLookupValue.IncorrectRepositoryReferencePackageLookupValue;
 import com.google.devtools.build.lib.vfs.PathFragment;
 import com.google.devtools.build.skyframe.SkyFunction;
@@ -49,6 +50,9 @@
       return env.getValue(ContainingPackageLookupValue.key(correctPackageIdentifier));
     }
 
+    if (ErrorReason.REPOSITORY_NOT_FOUND.equals(pkgLookupValue.getErrorReason())) {
+      return new ContainingPackageLookupValue.NoContainingPackage(pkgLookupValue.getErrorMsg());
+    }
     PathFragment parentDir = dir.getPackageFragment().getParentDirectory();
     if (parentDir == null) {
       return ContainingPackageLookupValue.NONE;

diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/ContainingPackageLookupValue.java b/src/main/java/com/google/devtools/build/lib/skyframe/ContainingPackageLookupValue.java
index 7ab319c..302d6db 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/ContainingPackageLookupValue.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/ContainingPackageLookupValue.java

@@ -26,6 +26,7 @@
 import com.google.devtools.build.skyframe.SkyFunctionName;
 import com.google.devtools.build.skyframe.SkyKey;
 import com.google.devtools.build.skyframe.SkyValue;
+import javax.annotation.Nonnull;
 
 /**
  * A value that represents the result of looking for the existence of a package that owns a
@@ -45,6 +46,14 @@
   /** If there is a containing package, returns its package root */
   public abstract Root getContainingPackageRoot();
 
+  /**
+   * If there is not a containing package, returns a reason why (this is usually the reason the
+   * outer-most directory isn't a package).
+   */
+  public String getReasonForNoContainingPackage() {
+    throw new IllegalStateException();
+  }
+
   public static Key key(PackageIdentifier id) {
     Preconditions.checkArgument(!id.getPackageFragment().isAbsolute(), id);
     Preconditions.checkArgument(!id.getRepository().isDefault(), id);
@@ -112,7 +121,15 @@
 
   /** Value indicating there is no containing package. */
   public static class NoContainingPackage extends ContainingPackageLookupValue {
-    private NoContainingPackage() {}
+    private final String reason;
+
+    private NoContainingPackage() {
+      this.reason = null;
+    }
+
+    NoContainingPackage(@Nonnull String reason) {
+      this.reason = reason;
+    }
 
     @Override
     public boolean hasContainingPackage() {
@@ -133,6 +150,11 @@
     public String toString() {
       return getClass().getName();
     }
+
+    @Override
+    public String getReasonForNoContainingPackage() {
+      return reason;
+    }
   }
 
   /** A successful lookup value. */

diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/PackageLookupFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/PackageLookupFunction.java
index aed63e4..95fe4be 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/PackageLookupFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/PackageLookupFunction.java

@@ -321,7 +321,7 @@
     }
     if (!repositoryValue.repositoryExists()) {
       // TODO(ulfjack): Maybe propagate the error message from the repository delegator function?
-      return PackageLookupValue.NO_SUCH_REPOSITORY_VALUE;
+      return new PackageLookupValue.NoRepositoryPackageLookupValue(id.getRepository().getName());
     }
 
     // This checks for the build file names in the correct precedence order.

diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/PackageLookupValue.java b/src/main/java/com/google/devtools/build/lib/skyframe/PackageLookupValue.java
index f5c5f8c..7d24e17 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/PackageLookupValue.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/PackageLookupValue.java

@@ -51,10 +51,6 @@
   public static final DeletedPackageLookupValue DELETED_PACKAGE_VALUE =
       new DeletedPackageLookupValue();
 
-  @AutoCodec
-  public static final NoRepositoryPackageLookupValue NO_SUCH_REPOSITORY_VALUE =
-      new NoRepositoryPackageLookupValue();
-
   enum ErrorReason {
     /** There is no BUILD file. */
     NO_BUILD_FILE,
@@ -391,11 +387,15 @@
   }
 
   /**
-   * Marker value for repository we could not find. This can happen when looking for a label that
-   * specifies a non-existent repository.
+   * Value for repository we could not find. This can happen when looking for a label that specifies
+   * a non-existent repository.
    */
   public static class NoRepositoryPackageLookupValue extends UnsuccessfulPackageLookupValue {
-    private NoRepositoryPackageLookupValue() {}
+    private final String repositoryName;
+
+    NoRepositoryPackageLookupValue(String repositoryName) {
+      this.repositoryName = repositoryName;
+    }
 
     @Override
     ErrorReason getErrorReason() {
@@ -404,7 +404,7 @@
 
     @Override
     public String getErrorMsg() {
-      return "The repository could not be resolved";
+      return String.format("The repository '%s' could not be resolved", repositoryName);
     }
   }
 }

diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/SkylarkImportLookupFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/SkylarkImportLookupFunction.java
index 0c3c081..179dc54 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/SkylarkImportLookupFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/SkylarkImportLookupFunction.java

@@ -249,7 +249,8 @@
         return null;
       }
       if (!containingPackageLookupValue.hasContainingPackage()) {
-        throw SkylarkImportFailedException.noBuildFile(fileLabel.toPathFragment());
+        throw SkylarkImportFailedException.noBuildFile(
+            fileLabel, containingPackageLookupValue.getReasonForNoContainingPackage());
       }
       if (!containingPackageLookupValue.getContainingPackageName().equals(
           fileLabel.getPackageIdentifier())) {
@@ -600,7 +601,11 @@
           cause);
     }
 
-    static SkylarkImportFailedException noBuildFile(PathFragment file) {
+    static SkylarkImportFailedException noBuildFile(Label file, @Nullable String reason) {
+      if (reason != null) {
+        return new SkylarkImportFailedException(
+            String.format("Unable to find package for %s: %s.", file, reason));
+      }
       return new SkylarkImportFailedException(
           String.format("Every .bzl file must have a corresponding package, but '%s' "
               + "does not have one. Please create a BUILD file in the same or any parent directory."