Add a flag to disable Make variables in the C++ configuration.

RELNOTES: None.
PiperOrigin-RevId: 172901568

2 files changed, 18 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppConfiguration.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppConfiguration.java
index 359dbb2eb1..5e9e96e721 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppConfiguration.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppConfiguration.java
@@ -1526,6 +1526,10 @@ public class CppConfiguration extends BuildConfiguration.Fragment {
 
   @Override
   public void addGlobalMakeVariables(Builder<String, String> globalMakeEnvBuilder) {
+    if (!cppOptions.enableMakeVariables) {
+      return;
+    }
+
     // hardcoded CC->gcc setting for unit tests
     globalMakeEnvBuilder.put("CC", getToolPathFragment(Tool.GCC).getPathString());
 
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppOptions.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppOptions.java
index 0e3b7a9379..6a91fc6696 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppOptions.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppOptions.java
@@ -852,6 +852,18 @@ public class CppOptions extends FragmentOptions {
   )
   public boolean strictSystemIncludes;
 
+ @Option(
+      name = "experimental_enable_cc_configuration_make_variables",
+      defaultValue = "true",
+      documentationCategory = OptionDocumentationCategory.UNDOCUMENTED,
+      effectTags = {OptionEffectTag.UNKNOWN},
+      metadataTags = {OptionMetadataTag.INCOMPATIBLE_CHANGE},
+      help = "If enabled, the C++ configuration fragment supplies Make variables. This option "
+          + "is used in the migration to remove them in favor of requiring an explicit "
+          + "dependency on the C++ toolchain for rules that use them."
+  )
+  public boolean enableMakeVariables;
+
   @Override
   public FragmentOptions getHost() {
     CppOptions host = (CppOptions) getDefault();
@@ -865,6 +877,8 @@ public class CppOptions extends FragmentOptions {
       host.crosstoolTop = hostCrosstoolTop;
     }
 
+    host.enableMakeVariables = enableMakeVariables;
+
     // hostLibcTop doesn't default to the target's libcTop.
     // Only an explicit command-line option will change it.
     // The default is whatever the host's crosstool (which might have been specified