commit a752d8b83ff3a241076b121dff989eb3def9cfb6
author laurentlb <laurentlb@google.com> Wed Jul 12 22:12:04 2017 +0200
committer László Csomor <laszlocsomor@google.com> Thu Jul 13 09:56:32 2017 +0200
tree 2c8919801d13f1c7306a11ef3352461eb87e5338
parent 5f36bf8a0716434348042c088da838728dc6dcdc

New flag --incompatible_string_is_not_iterable to forbid iteration over strings.

RELNOTES: None.
PiperOrigin-RevId: 161706309

src/main/java/com/google/devtools/build/lib/syntax/EvalUtils.java

diff --git a/src/main/java/com/google/devtools/build/lib/syntax/EvalUtils.java b/src/main/java/com/google/devtools/build/lib/syntax/EvalUtils.java
index 7ef2eb3..e6e9089 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/EvalUtils.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/EvalUtils.java
@@ -348,7 +348,7 @@
     if (o instanceof String) {
       // This is not as efficient as special casing String in for and dict and list comprehension
       // statements. However this is a more unified way.
-      return split((String) o);
+      return split((String) o, loc, env);
     } else if (o instanceof SkylarkNestedSet) {
       return nestedSetToCollection((SkylarkNestedSet) o, loc, env);
     } else if (o instanceof Iterable) {
@@ -401,7 +401,15 @@
     }
   }
 
-  private static ImmutableList<String> split(String value) {
+  private static ImmutableList<String> split(String value, Location loc, @Nullable Environment env)
+      throws EvalException {
+    if (env != null && env.getSemantics().incompatibleStringIsNotIterable) {
+      throw new EvalException(
+          loc,
+          "type 'string' is not iterable. You may still use `len` and string indexing. Use "
+              + "--incompatible_string_is_not_iterable=false to temporarily disable this check.");
+    }
+
     ImmutableList.Builder<String> builder = new ImmutableList.Builder<>();
     for (char c : value.toCharArray()) {
       builder.add(String.valueOf(c));