[Serialization] Downgrade inconsistent flags from erros to warnings

clang/docs/ReleaseNotes.rst

@@ -590,6 +590,8 @@ Improvements to Clang's diagnostics
 
 - Fixed a false negative ``-Wunused-private-field`` diagnostic when a defaulted comparison operator is defined out of class (#GH116961).
 
+- Clang now downgrades the inconsistent language options between modules to warnings instead of errors.
+
 Improvements to Clang's time-trace
 ----------------------------------
 

clang/include/clang/Basic/DiagnosticGroups.td

@@ -557,6 +557,7 @@ def ModuleLock : DiagGroup<"module-lock">;
 def ModuleBuild : DiagGroup<"module-build">;
 def ModuleImport : DiagGroup<"module-import">;
 def ModuleConflict : DiagGroup<"module-conflict">;
+def ModuleMismatchedOption : DiagGroup<"module-mismatched-option">;
 def ModuleFileExtension : DiagGroup<"module-file-extension">;
 def ModuleIncludeDirectiveTranslation : DiagGroup<"module-include-translation">;
 def RoundTripCC1Args : DiagGroup<"round-trip-cc1-args">;

clang/include/clang/Basic/DiagnosticSerializationKinds.td

@@ -36,10 +36,12 @@ def err_ast_file_targetopt_feature_mismatch : Error<
     "%select{AST file '%1' was|current translation unit is}0 compiled with the target "
     "feature '%2' but the %select{current translation unit is|AST file '%1' was}0 "
     "not">;
-def err_ast_file_langopt_mismatch : Error<"%0 was %select{disabled|enabled}1 in "
-    "AST file '%3' but is currently %select{disabled|enabled}2">;
-def err_ast_file_langopt_value_mismatch : Error<
-  "%0 differs in AST file '%1' vs. current file">;
+def warn_ast_file_langopt_mismatch : Warning<"%0 was %select{disabled|enabled}1 in "
+    "AST file '%3' but is currently %select{disabled|enabled}2">,
+    InGroup<ModuleMismatchedOption>;
+def warn_ast_file_langopt_value_mismatch : Warning<
+  "%0 differs in AST file '%1' vs. current file">,
+  InGroup<ModuleMismatchedOption>;
 def err_ast_file_diagopt_mismatch : Error<"%0 is currently enabled, but was not in "
   "the AST file '%1'">;
 def err_ast_file_modulecache_mismatch : Error<"AST file '%2' was compiled with module cache "

clang/lib/Serialization/ASTReader.cpp

@@ -279,9 +279,7 @@ ASTReaderListener::~ASTReaderListener() = default;
 /// \param Diags If non-NULL, diagnostics will be emitted via this engine.
 /// \param AllowCompatibleDifferences If true, differences between compatible
 ///        language options will be permitted.
-///
-/// \returns true if the languagae options mis-match, false otherwise.
-static bool checkLanguageOptions(const LangOptions &LangOpts,
+static void checkLanguageOptions(const LangOptions &LangOpts,
                                  const LangOptions &ExistingLangOpts,
                                  StringRef ModuleFilename,
                                  DiagnosticsEngine *Diags,
@@ -290,30 +288,27 @@ static bool checkLanguageOptions(const LangOptions &LangOpts,
   if (ExistingLangOpts.Name != LangOpts.Name) {                                \
     if (Diags) {                                                               \
       if (Bits == 1)                                                           \
-        Diags->Report(diag::err_ast_file_langopt_mismatch)                     \
+        Diags->Report(diag::warn_ast_file_langopt_mismatch)                    \
             << Description << LangOpts.Name << ExistingLangOpts.Name           \
             << ModuleFilename;                                                 \
       else                                                                     \
-        Diags->Report(diag::err_ast_file_langopt_value_mismatch)               \
+        Diags->Report(diag::warn_ast_file_langopt_value_mismatch)              \
             << Description << ModuleFilename;                                  \
     }                                                                          \
-    return true;                                                               \
   }
 
 #define VALUE_LANGOPT(Name, Bits, Default, Description)                        \
   if (ExistingLangOpts.Name != LangOpts.Name) {                                \
     if (Diags)                                                                 \
-      Diags->Report(diag::err_ast_file_langopt_value_mismatch)                 \
+      Diags->Report(diag::warn_ast_file_langopt_value_mismatch)                \
           << Description << ModuleFilename;                                    \
-    return true;                                                               \
   }
 
 #define ENUM_LANGOPT(Name, Type, Bits, Default, Description)                   \
   if (ExistingLangOpts.get##Name() != LangOpts.get##Name()) {                  \
     if (Diags)                                                                 \
-      Diags->Report(diag::err_ast_file_langopt_value_mismatch)                 \
+      Diags->Report(diag::warn_ast_file_langopt_value_mismatch)                \
           << Description << ModuleFilename;                                    \
-    return true;                                                               \
   }
 
 #define COMPATIBLE_LANGOPT(Name, Bits, Default, Description)  \
@@ -335,24 +330,21 @@ static bool checkLanguageOptions(const LangOptions &LangOpts,
 
   if (ExistingLangOpts.ModuleFeatures != LangOpts.ModuleFeatures) {
     if (Diags)
-      Diags->Report(diag::err_ast_file_langopt_value_mismatch)
+      Diags->Report(diag::warn_ast_file_langopt_value_mismatch)
           << "module features" << ModuleFilename;
-    return true;
   }
 
   if (ExistingLangOpts.ObjCRuntime != LangOpts.ObjCRuntime) {
     if (Diags)
-      Diags->Report(diag::err_ast_file_langopt_value_mismatch)
+      Diags->Report(diag::warn_ast_file_langopt_value_mismatch)
           << "target Objective-C runtime" << ModuleFilename;
-    return true;
   }
 
   if (ExistingLangOpts.CommentOpts.BlockCommandNames !=
       LangOpts.CommentOpts.BlockCommandNames) {
     if (Diags)
-      Diags->Report(diag::err_ast_file_langopt_value_mismatch)
+      Diags->Report(diag::warn_ast_file_langopt_value_mismatch)
           << "block command names" << ModuleFilename;
-    return true;
   }
 
   // Sanitizer feature mismatches are treated as compatible differences. If
@@ -378,11 +370,8 @@ static bool checkLanguageOptions(const LangOptions &LangOpts,
   }
 #include "clang/Basic/Sanitizers.def"
       }
-      return true;
     }
   }
-
-  return false;
 }
 
 /// Compare the given set of target options against an existing set of
@@ -459,9 +448,10 @@ bool PCHValidator::ReadLanguageOptions(const LangOptions &LangOpts,
                                        StringRef ModuleFilename, bool Complain,
                                        bool AllowCompatibleDifferences) {
   const LangOptions &ExistingLangOpts = PP.getLangOpts();
-  return checkLanguageOptions(LangOpts, ExistingLangOpts, ModuleFilename,
-                              Complain ? &Reader.Diags : nullptr,
-                              AllowCompatibleDifferences);
+  checkLanguageOptions(LangOpts, ExistingLangOpts, ModuleFilename,
+                       Complain ? &Reader.Diags : nullptr,
+                       AllowCompatibleDifferences);
+  return false;
 }
 
 bool PCHValidator::ReadTargetOptions(const TargetOptions &TargetOpts,
@@ -5398,8 +5388,9 @@ namespace {
     bool ReadLanguageOptions(const LangOptions &LangOpts,
                              StringRef ModuleFilename, bool Complain,
                              bool AllowCompatibleDifferences) override {
-      return checkLanguageOptions(ExistingLangOpts, LangOpts, ModuleFilename,
-                                  nullptr, AllowCompatibleDifferences);
+      checkLanguageOptions(ExistingLangOpts, LangOpts, ModuleFilename, nullptr,
+                           AllowCompatibleDifferences);
+      return false;
     }
 
     bool ReadTargetOptions(const TargetOptions &TargetOpts,

clang/test/Modules/explicit-build-missing-files.cpp

@@ -33,7 +33,7 @@
 // RUN: %clang_cc1 -fmodules -I %t -fmodule-file=%t/b.pcm %s
 // RUN: not %clang_cc1 -fmodules -I %t -fmodule-file=%t/a.pcm %s -DERRORS 2>&1 | FileCheck %s --check-prefix=MISSING-B
 // RUN: %clang_cc1 -fmodules -I %t -fmodule-file=%t/a.pcm -fmodule-map-file=%t/modulemap.moved %s
-// RUN: not %clang_cc1 -fmodules -I %t -fmodule-file=%t/a.pcm -fmodule-map-file=%t/modulemap.moved -std=c++1z %s
+// RUN: %clang_cc1 -fmodules -I %t -fmodule-file=%t/a.pcm -fmodule-map-file=%t/modulemap.moved -std=c++1z %s
 // RUN: %clang_cc1 -fmodules -I %t -fmodule-file=%t/a.pcm -fmodule-map-file=%t/modulemap.moved -std=c++1z -Wno-module-file-config-mismatch %s -Db=a
 // RUN: rm %t/a.h
 // RUN: %clang_cc1 -fmodules -I %t -fmodule-file=%t/a.pcm %s -verify

clang/test/Modules/load_failure.c

@@ -11,11 +11,11 @@
 // RUN: not %clang_cc1 -fmodules -fimplicit-module-maps -x objective-c -fmodules-cache-path=%t -I %S/Inputs -fdisable-module-hash %s -DNONEXISTENT 2>&1 | FileCheck -check-prefix=CHECK-NONEXISTENT %s
 // CHECK-NONEXISTENT: load_failure.c:2:9: fatal error: module 'load_nonexistent' not found
 
-// RUN: not %clang_cc1 -fmodules -fimplicit-module-maps -x objective-c -fmodules-cache-path=%t -I %S/Inputs -fdisable-module-hash %s -DFAILURE 2> %t.out
-// RUN: FileCheck -check-prefix=CHECK-FAILURE %s < %t.out
+// RUN: %clang_cc1 -fmodules -fimplicit-module-maps -x objective-c -fmodules-cache-path=%t -I %S/Inputs -fdisable-module-hash %s -DFAILURE 2> %t.out
+// RUN: FileCheck -check-prefix=CHECK-WARN %s < %t.out
 
 // FIXME: Clean up diagnostic text below and give it a location
-// CHECK-FAILURE: error: C99 was disabled in AST file '{{.*}}load_failure.pcm' but is currently enabled
+// CHECK-WARN: warning: C99 was disabled in AST file '{{.*}}load_failure.pcm' but is currently enabled
 // FIXME: When we have a syntax for modules in C, use that.
 
 

clang/test/Modules/mismatch-diagnostics.cpp

@@ -3,31 +3,55 @@
 // RUN: split-file %s %t
 // RUN: mkdir -p %t/prebuilt_modules
 //
-// RUN: %clang_cc1 -triple %itanium_abi_triple                          \
-// RUN:     -std=c++20 -fprebuilt-module-path=%t/prebuilt-modules       \
-// RUN:     -emit-module-interface -pthread -DBUILD_MODULE              \
-// RUN:     %t/mismatching_module.cppm -o                               \
+// RUN: %clang_cc1 -triple %itanium_abi_triple                           \
+// RUN:     -std=c++20 -fprebuilt-module-path=%t/prebuilt-modules        \
+// RUN:     -emit-module-interface -pthread -DBUILD_MODULE               \
+// RUN:     %t/mismatching_module.cppm -o                                \
 // RUN:     %t/prebuilt_modules/mismatching_module.pcm
 //
-// RUN: not %clang_cc1 -triple %itanium_abi_triple -std=c++20           \
-// RUN:     -fprebuilt-module-path=%t/prebuilt_modules -DCHECK_MISMATCH \
-// RUN:     %t/use.cpp 2>&1 | FileCheck %s
+// RUN: %clang_cc1 -triple %itanium_abi_triple -std=c++20                \
+// RUN:     -fprebuilt-module-path=%t/prebuilt_modules -DCHECK_MISMATCH  \
+// RUN:     %t/use.cpp 2>&1 | FileCheck %t/use.cpp
 
 // Test again with reduced BMI.
-// RUN: %clang_cc1 -triple %itanium_abi_triple                          \
-// RUN:     -std=c++20 -fprebuilt-module-path=%t/prebuilt-modules       \
-// RUN:     -emit-reduced-module-interface -pthread -DBUILD_MODULE              \
-// RUN:     %t/mismatching_module.cppm -o                               \
+// RUN: %clang_cc1 -triple %itanium_abi_triple                           \
+// RUN:     -std=c++20 -fprebuilt-module-path=%t/prebuilt-modules        \
+// RUN:     -emit-reduced-module-interface -pthread -DBUILD_MODULE       \
+// RUN:     %t/mismatching_module.cppm -o                                \
 // RUN:     %t/prebuilt_modules/mismatching_module.pcm
 //
-// RUN: not %clang_cc1 -triple %itanium_abi_triple -std=c++20           \
-// RUN:     -fprebuilt-module-path=%t/prebuilt_modules -DCHECK_MISMATCH \
-// RUN:     %t/use.cpp 2>&1 | FileCheck %s
+// RUN: %clang_cc1 -triple %itanium_abi_triple -std=c++20                \
+// RUN:     -fprebuilt-module-path=%t/prebuilt_modules -DCHECK_MISMATCH  \
+// RUN:     %t/use.cpp 2>&1 | FileCheck %t/use.cpp
+//
+// RUN: %clang_cc1 -triple %itanium_abi_triple                           \
+// RUN:     -std=c++20 -fprebuilt-module-path=%t/prebuilt-modules        \
+// RUN:     -emit-module-interface -pthread -DBUILD_MODULE               \
+// RUN:     %t/mismatching_module.cppm -o                                \
+// RUN:     %t/prebuilt_modules/mismatching_module.pcm
+//
+// RUN: %clang_cc1 -triple %itanium_abi_triple -std=c++20                \
+// RUN:     -fprebuilt-module-path=%t/prebuilt_modules -DCHECK_MISMATCH  \
+// RUN:     -Wno-module-mismatched-option %t/use.cpp 2>&1 | FileCheck %t/use.cpp \
+// RUN:     --check-prefix=NOWARN --allow-empty
+
+// Test again with reduced BMI.
+// RUN: %clang_cc1 -triple %itanium_abi_triple                           \
+// RUN:     -std=c++20 -fprebuilt-module-path=%t/prebuilt-modules        \
+// RUN:     -emit-reduced-module-interface -pthread -DBUILD_MODULE       \
+// RUN:     %t/mismatching_module.cppm -o                                \
+// RUN:     %t/prebuilt_modules/mismatching_module.pcm
+//
+// RUN: %clang_cc1 -triple %itanium_abi_triple -std=c++20                \
+// RUN:     -fprebuilt-module-path=%t/prebuilt_modules -DCHECK_MISMATCH  \
+// RUN:     -Wno-module-mismatched-option %t/use.cpp 2>&1 | FileCheck %t/use.cpp \
+// RUN:     --check-prefix=NOWARN --allow-empty
 
 //--- mismatching_module.cppm
 export module mismatching_module;
 
 //--- use.cpp
 import mismatching_module;
-// CHECK: error: POSIX thread support was enabled in AST file '{{.*[/|\\\\]}}mismatching_module.pcm' but is currently disabled
-// CHECK-NEXT: module file {{.*[/|\\\\]}}mismatching_module.pcm cannot be loaded due to a configuration mismatch with the current compilation
+// CHECK: warning: POSIX thread support was enabled in AST file '{{.*[/|\\\\]}}mismatching_module.pcm' but is currently disabled
+
+// NOWARN-NOT: warning

clang/test/Modules/module-feature.m

@@ -6,9 +6,9 @@
 // RUN: %clang_cc1 -fmodules -fmodules-cache-path=%t -fimplicit-module-maps -fmodule-feature f2 -fmodule-feature f1 -F %S/Inputs %s -Rmodule-build 2>&1 | FileCheck %s -allow-empty -check-prefix=ALREADY_BUILT
 // ALREADY_BUILT-NOT: building module
 
-// Errors if we try to force the load.
+// Warns if we try to force the load.
 // RUN: %clang_cc1 -fmodules -fmodules-cache-path=%t.nohash -fimplicit-module-maps -fdisable-module-hash -fmodule-feature f1 -fmodule-feature f2 -F %S/Inputs %s -verify -Rmodule-build
-// RUN: not %clang_cc1 -fmodules -fmodules-cache-path=%t.nohash -fimplicit-module-maps -fdisable-module-hash -fmodule-feature f2 -F %S/Inputs %s 2>&1 | FileCheck %s -check-prefix=DIFFERS
-// DIFFERS: error: module features differs
+// RUN: %clang_cc1 -fmodules -fmodules-cache-path=%t.nohash -fimplicit-module-maps -fdisable-module-hash -fmodule-feature f2 -F %S/Inputs %s 2>&1 | FileCheck %s -check-prefix=DIFFERS
+// DIFFERS: warning: module features differs
 
 @import Module; // expected-remark {{building module 'Module'}} expected-remark {{finished}}

clang/test/Modules/pr62359.cppm

@@ -3,9 +3,9 @@
 // RUN: split-file %s %t
 //
 // RUN: %clang_cc1 -std=c++20 -emit-module-interface %t/Hello.cppm -o %t/Hello.pcm
-// RUN: not %clang_cc1 -std=c++20 -fopenmp %t/use.cpp -fmodule-file=hello=%t/Hello.pcm -fsyntax-only \
+// RUN: %clang_cc1 -std=c++20 -fopenmp %t/use.cpp -fmodule-file=hello=%t/Hello.pcm -fsyntax-only \
 // RUN:     2>&1 | FileCheck %t/use.cpp
-// RUN: not %clang_cc1 -std=c++20 -fopenmp %t/use2.cpp -fmodule-file=hello=%t/Hello.pcm -fsyntax-only \
+// RUN: %clang_cc1 -std=c++20 -fopenmp %t/use2.cpp -fmodule-file=hello=%t/Hello.pcm -fsyntax-only \
 // RUN:     2>&1 | FileCheck %t/use2.cpp
 //
 // RUN: %clang_cc1 -std=c++20 -fopenmp -emit-module-interface %t/Hello.cppm -o %t/Hello.pcm
@@ -18,9 +18,9 @@
 // RUN: split-file %s %t
 //
 // RUN: %clang_cc1 -std=c++20 -emit-reduced-module-interface %t/Hello.cppm -o %t/Hello.pcm
-// RUN: not %clang_cc1 -std=c++20 -fopenmp %t/use.cpp -fmodule-file=hello=%t/Hello.pcm -fsyntax-only \
+// RUN: %clang_cc1 -std=c++20 -fopenmp %t/use.cpp -fmodule-file=hello=%t/Hello.pcm -fsyntax-only \
 // RUN:     2>&1 | FileCheck %t/use.cpp
-// RUN: not %clang_cc1 -std=c++20 -fopenmp %t/use2.cpp -fmodule-file=hello=%t/Hello.pcm -fsyntax-only \
+// RUN: %clang_cc1 -std=c++20 -fopenmp %t/use2.cpp -fmodule-file=hello=%t/Hello.pcm -fsyntax-only \
 // RUN:     2>&1 | FileCheck %t/use2.cpp
 //
 // RUN: %clang_cc1 -std=c++20 -fopenmp -emit-reduced-module-interface %t/Hello.cppm -o %t/Hello.pcm
@@ -56,4 +56,3 @@ int use2() {
 }
 
 // CHECK: OpenMP{{.*}}differs in AST file '{{.*}}Hello.pcm' vs. current file
-// CHECK: use of undeclared identifier 'pragma'

clang/test/Modules/prebuilt-implicit-modules.m

@@ -25,7 +25,7 @@
 // RUN: mkdir -p %t2
 // RUN: %clang_cc1 -x objective-c -fmodules %S/Inputs/prebuilt-implicit-module/module.modulemap -emit-module -fmodule-name=module_a -fmodules-cache-path=%t
 // RUN: %clang_cc1 -x objective-c -fmodules %S/Inputs/prebuilt-implicit-module/module.modulemap -emit-module -fmodule-name=module_a -o %t/module_a.pcm -fno-signed-char
-// RUN: not %clang_cc1 -x objective-c %s -I%S/Inputs/prebuilt-implicit-module -fmodules -fmodule-map-file=%S/Inputs/prebuilt-implicit-module/module.modulemap -fprebuilt-implicit-modules -fprebuilt-module-path=%t -fmodules-cache-path=%t2
+// RUN: %clang_cc1 -x objective-c %s -I%S/Inputs/prebuilt-implicit-module -fmodules -fmodule-map-file=%S/Inputs/prebuilt-implicit-module/module.modulemap -fprebuilt-implicit-modules -fprebuilt-module-path=%t -fmodules-cache-path=%t2
 // RUN: find %t2 -name "module_a*.pcm" | not grep module_a
 
 // expected-no-diagnostics

clang/test/PCH/arc.m

@@ -6,10 +6,10 @@
 // RUN: %clang_cc1 -emit-pch -fblocks -triple x86_64-apple-darwin11 -fobjc-arc -x objective-c-header -o %t %S/Inputs/arc.h
 // RUN: %clang_cc1 -fblocks -triple x86_64-apple-darwin11 -fobjc-arc -include-pch %t -emit-llvm-only %s 
 
-// Test error when pch's -fobjc-arc state is different.
-// RUN: not %clang_cc1 -fblocks -triple x86_64-apple-darwin11 -include-pch %t -emit-llvm-only %s 2>&1 | FileCheck -check-prefix=CHECK-ERR1 %s 
+// Test warning when pch's -fobjc-arc state is different.
+// RUN: %clang_cc1 -fblocks -triple x86_64-apple-darwin11 -include-pch %t -emit-llvm-only %s 2>&1 | FileCheck -check-prefix=CHECK-ERR1 %s 
 // RUN: %clang_cc1 -emit-pch -fblocks -triple x86_64-apple-darwin11 -x objective-c-header -o %t %S/Inputs/arc.h
-// RUN: not %clang_cc1 -fblocks -triple x86_64-apple-darwin11 -fobjc-arc -include-pch %t -emit-llvm-only %s 2>&1 | FileCheck -check-prefix=CHECK-ERR2 %s
+// RUN: %clang_cc1 -fblocks -triple x86_64-apple-darwin11 -fobjc-arc -include-pch %t -emit-llvm-only %s 2>&1 | FileCheck -check-prefix=CHECK-ERR2 %s
 
 array0 a0;
 array1 a1;

clang/test/PCH/no-validate-pch.cl

@@ -16,7 +16,7 @@
 // CHECK: note: previous definition is here
 // CHECK: #define X 4
 
-// CHECK-VAL: error: __OPTIMIZE__ predefined macro was enabled in AST file '{{.*}}' but is currently disabled
+// CHECK-VAL: warning: __OPTIMIZE__ predefined macro was enabled in AST file '{{.*}}' but is currently disabled
 // CHECK-VAL: error: definition of macro 'X' differs between the AST file '{{.*}}' ('4') and the command line ('5')
 
 void test(void) {

clang/test/PCH/pch-dir.c

@@ -11,11 +11,11 @@
 // RUN: %clang -x c++ -include %t.h -std=c++98 -fsyntax-only %s -Xclang -print-stats 2> %t.cpplog
 // RUN: FileCheck -check-prefix=CHECK-CPP %s < %t.cpplog
 
-// RUN: not %clang -x c++ -std=c++11 -include %t.h -fsyntax-only %s 2> %t.cpp11log
-// RUN: FileCheck -check-prefix=CHECK-NO-SUITABLE %s < %t.cpp11log
+// RUN: %clang -x c++ -std=c++11 -include %t.h -fsyntax-only %s 2> %t.cpp11log
+// RUN: FileCheck %s --check-prefix=CHECK-OPT-DIFF < %t.cpp11log
 
-// RUN: not %clang -include %t.h -fsyntax-only %s 2> %t.missinglog2
-// RUN: FileCheck -check-prefix=CHECK-NO-SUITABLE %s < %t.missinglog2
+// RUN: %clang -include %t.h -fsyntax-only %s 2> %t.missinglog2
+// RUN: FileCheck --check-prefix=CHECK-OPT-DIFF %s < %t.missinglog2
 // RUN: not %clang -include %t.h -DFOO=foo -DBAR=bar -fsyntax-only %s 2> %t.missinglog2
 // RUN: FileCheck -check-prefix=CHECK-NO-SUITABLE %s < %t.missinglog2
 
@@ -41,6 +41,8 @@ int get(void) {
 #endif
 }
 
+// CHECK-OPT-DIFF: warning: {{.*}} was disabled in AST file{{.*}} but is currently enabled
+
 // CHECK-NO-SUITABLE: no suitable precompiled header file found in directory
 
 // CHECK-IGNORED-DIR: precompiled header directory '{{.*}}pch-dir.c.tmp.x.h.gch' was ignored because it contains no clang PCH files