[modules] Allow the error when explicitly loading an incompatible module file

via -fmodule-file= to be turned off; in that case, just include the relevant
files textually. This allows module files to be unconditionally passed to all
compile actions via CXXFLAGS, and to be ignored for rules that specify custom
incompatible flags.

llvm-svn: 250577

clang/include/clang/Basic/DiagnosticFrontendKinds.td

@@ -172,6 +172,9 @@ def warn_incompatible_analyzer_plugin_api : Warning<
 def note_incompatible_analyzer_plugin_api : Note<
     "current API version is '%0', but plugin was compiled with version '%1'">;
 
+def warn_module_config_mismatch : Warning<
+  "module file %0 cannot be loaded due to a configuration mismatch with the current "
+  "compilation">, InGroup<DiagGroup<"module-file-config-mismatch">>, DefaultError;
 def err_module_map_not_found : Error<"module map file '%0' not found">, 
   DefaultFatal;
 def err_missing_module_name : Error<

clang/lib/Frontend/CompilerInstance.cpp

@@ -1335,15 +1335,24 @@ bool CompilerInstance::loadModuleFile(StringRef FileName) {
                                                    std::move(Listener));
 
   // Try to load the module file.
-  if (ModuleManager->ReadAST(FileName, serialization::MK_ExplicitModule,
-                             SourceLocation(), ASTReader::ARR_None)
-          != ASTReader::Success)
-    return false;
-
+  switch (ModuleManager->ReadAST(FileName, serialization::MK_ExplicitModule,
+                                 SourceLocation(),
+                                 ASTReader::ARR_ConfigurationMismatch)) {
+  case ASTReader::Success:
   // We successfully loaded the module file; remember the set of provided
   // modules so that we don't try to load implicit modules for them.
   ListenerRef.registerAll();
   return true;
+
+  case ASTReader::ConfigurationMismatch:
+    // Ignore unusable module files.
+    getDiagnostics().Report(SourceLocation(), diag::warn_module_config_mismatch)
+        << FileName;
+    return true;
+
+  default:
+    return false;
+  }
 }
 
 ModuleLoadResult

clang/test/Modules/merge-target-features.cpp

@@ -20,7 +20,7 @@
 // RUN:   -target-cpu i386 \
 // RUN:   -fsyntax-only merge-target-features.cpp 2>&1 \
 // RUN:   | FileCheck --check-prefix=SUBSET %s
-// SUBSET: AST file was compiled with the target feature'+sse2' but the current translation unit is not
+// SUBSET: error: {{.*}} configuration mismatch
 //
 // RUN: %clang_cc1 -fmodules -x c++ -fmodules-cache-path=%t \
 // RUN:   -iquote Inputs/merge-target-features \
@@ -56,8 +56,7 @@
 // RUN:   -target-cpu i386 -target-feature +cx16 \
 // RUN:   -fsyntax-only merge-target-features.cpp 2>&1 \
 // RUN:   | FileCheck --check-prefix=MISMATCH %s
-// MISMATCH: AST file was compiled with the target feature'+sse2' but the current translation unit is not
-// MISMATCH: current translation unit was compiled with the target feature'+cx16' but the AST file was not
+// MISMATCH: error: {{.*}} configuration mismatch
 
 #include "foo.h"