Hide fix for linkstmap inputs computation behind an option

This cl introduces a bazel option
(--experimental_fix_linkstamp_inputs_bug_73447914) to control which inputs get
added into C++ linkstamp compile action. When set to true (defaults to false),
all inputs of relevant C++ linking action get added as inputs to the linkstamp
compile action too.

RELNOTES: None.
PiperOrigin-RevId: 187030217

3 files changed, 40 insertions, 7 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 00eeea8994..e0b1e53a0b 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
@@ -200,6 +200,8 @@ public final class CppConfiguration extends BuildConfiguration.Fragment {
 
   private final boolean shouldProvideMakeVariables;
 
+  private final boolean fixLinkstampInputsBug;
+
   /**
    * If true, the ConfiguredTarget is only used to get the necessary cross-referenced {@code
    * CcCompilationInfo}s, but registering build actions is disabled.
@@ -315,6 +317,7 @@ public final class CppConfiguration extends BuildConfiguration.Fragment {
         ImmutableList.copyOf(cppOptions.ltoindexoptList),
         cppOptions,
         params.cpuTransformer,
+        cppOptions.fixLinkstampInputsBug,
         (cppOptions.stripBinaries == StripMode.ALWAYS
             || (cppOptions.stripBinaries == StripMode.SOMETIMES
                 && compilationMode == CompilationMode.FASTBUILD)),
@@ -351,6 +354,7 @@ public final class CppConfiguration extends BuildConfiguration.Fragment {
       ImmutableList<String> ltoindexOptions,
       CppOptions cppOptions,
       CpuTransformer cpuTransformerEnum,
+      boolean fixLinkstampInputsBug,
       boolean stripBinaries,
       CompilationMode compilationMode,
       boolean shouldProvideMakeVariables,
@@ -381,6 +385,7 @@ public final class CppConfiguration extends BuildConfiguration.Fragment {
     this.ltoindexOptions = ltoindexOptions;
     this.cppOptions = cppOptions;
     this.cpuTransformerEnum = cpuTransformerEnum;
+    this.fixLinkstampInputsBug = fixLinkstampInputsBug;
     this.stripBinaries = stripBinaries;
     this.compilationMode = compilationMode;
     this.shouldProvideMakeVariables = shouldProvideMakeVariables;
@@ -421,6 +426,10 @@ public final class CppConfiguration extends BuildConfiguration.Fragment {
     return cpuTransformerEnum.getTransformer();
   }
 
+  public boolean shouldFixLinkstampInputsBug() {
+    return fixLinkstampInputsBug;
+  }
+
   /**
    * Returns the path of the crosstool.
    */
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppLinkActionBuilder.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppLinkActionBuilder.java
index 6e652378ae..2b9447a755 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppLinkActionBuilder.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppLinkActionBuilder.java
@@ -1191,19 +1191,25 @@ public class CppLinkActionBuilder {
 
     if (!isLtoIndexing) {
       for (Entry<Linkstamp, Artifact> linkstampEntry : linkstampMap.entrySet()) {
+        Iterable<Artifact> inputs;
+        if (cppConfiguration.shouldFixLinkstampInputsBug()) {
+          inputs = IterablesChain.<Artifact>builder()
+              .add(ImmutableSet.copyOf(nonCodeInputs))
+              // We don't want to add outputs of this linkstamp compilation action to
+              // inputsBuilder before this line, since that would introduce a cycle in the
+              // graph.
+              .add(inputsBuilder.deduplicate().build())
+              .build();
+        } else {
+          inputs = ImmutableSet.copyOf(nonCodeInputs);
+        }
         analysisEnvironment.registerAction(
             CppLinkstampCompileHelper.createLinkstampCompileAction(
                 ruleContext,
                 linkstampEntry.getKey().getArtifact(),
                 linkstampEntry.getValue(),
                 linkstampEntry.getKey().getDeclaredIncludeSrcs(),
-                NestedSetBuilder.<Artifact>stableOrder()
-                    .addAll(nonCodeInputs)
-                    // We don't want to add outputs of this linkstamp compilation action to
-                    // inputsBuilder before this line, since that would introduce a cycle in the
-                    // graph.
-                    .addAll(inputsBuilder.deduplicate().build())
-                    .build(),
+                inputs,
                 buildInfoHeaderArtifacts,
                 additionalLinkstampDefines,
                 toolchain,
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 5ca58c20fd..54ee2a97f1 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
@@ -888,6 +888,24 @@ public class CppOptions extends FragmentOptions {
   )
   public boolean useLLVMCoverageMapFormat;
 
+  @Option(
+      name = "experimental_fix_linkstamp_inputs_bug",
+      defaultValue = "false",
+      category = "experimental",
+      documentationCategory = OptionDocumentationCategory.UNDOCUMENTED,
+      effectTags = {
+          OptionEffectTag.CHANGES_INPUTS,
+          OptionEffectTag.AFFECTS_OUTPUTS,
+          OptionEffectTag.LOADING_AND_ANALYSIS
+      },
+      metadataTags = {OptionMetadataTag.EXPERIMENTAL},
+      help =
+          "If set to true, bazel will add all inputs of the C++ linking action as inputs to the "
+              + "C++ linkstamp compile action too. This is a migration-only flag and will be "
+              + "removed as soon as g3 is fixed."
+  )
+  public boolean fixLinkstampInputsBug;
+
   @Override
   public FragmentOptions getHost() {
     CppOptions host = (CppOptions) getDefault();