[clang][cas] Ignore indexing options when computing the CAS key

Indexing data are allowed to "escape" the CAS sandbox without indexing options affecting the CAS key.
Essentially indexing data are produced when the compilation is executed but they are not replayed if the compilation is cached.

Author: akyrtzi

clang/lib/Frontend/CompileJobCacheKey.cpp

@@ -74,6 +74,20 @@ createCompileJobCacheKeyImpl(ObjectStore &CAS, DiagnosticsEngine &Diags,
   // affect the actual compilation.
   DepOpts.ExtraDeps.clear();
 
+  // Canonicalize indexing options.
+
+  // Indexing data are allowed to "escape" the CAS sandbox without indexing
+  // options affecting the CAS key. Essentially indexing data are produced when
+  // the compilation is executed but they are not replayed if the compilation is
+  // cached.
+
+  FrontendOpts.IndexStorePath.clear();
+  FrontendOpts.IndexUnitOutputPath.clear();
+  FrontendOpts.IndexIgnoreSystemSymbols = false;
+  FrontendOpts.IndexRecordCodegenName = false;
+  FrontendOpts.IndexIgnoreMacros = false;
+  FrontendOpts.IndexIgnorePcms = false;
+
   // Canonicalize diagnostic options.
 
   DiagnosticOptions &DiagOpts = CI.getDiagnosticOpts();

clang/test/CAS/indexing.c

@@ -0,0 +1,19 @@
+// Test that emitted indexing data are allowed to "escape" the CAS sandbox without indexing options affecting the CAS key
+// (essentially indexing data are produced when the compilation is executed but they are not replayed if the compilation is cached)
+
+// RUN: rm -rf %t && mkdir %t
+
+// RUN: %clang -cc1depscan -fdepscan=inline -fdepscan-include-tree -o %t/t.rsp -cc1-args \
+// RUN:   -cc1 -triple x86_64-apple-macos12 -fcas-path %t/cas -emit-obj %s -o %t/t.o
+
+// RUN: %clang @%t/t.rsp -Rcompile-job-cache -index-store-path %t/idx -index-unit-output-path t.o 2>&1 \
+// RUN:   | FileCheck %s --check-prefix=CACHE-MISS
+// RUN: find %t/idx/*/records | count 1
+
+// RUN: rm -rf %t/idx && mkdir %t/idx
+// RUN: %clang @%t/t.rsp -Rcompile-job-cache 2>&1 \
+// RUN:   | FileCheck %s --check-prefix=CACHE-HIT
+// RUN: ls %t/idx | count 0
+
+// CACHE-MISS: remark: compile job cache miss
+// CACHE-HIT: remark: compile job cache hit