[clang] 96122b5 - [C++20] [Modules] Introduce ForceCheckCXX20ModulesInputFiles options for

[Chuanqi Xu via cfe-commits]

Author: Chuanqi Xu
Date: 2023-09-08T16:53:12+08:00
New Revision: 96122b5b717c2b1a291d7298ac50b1daf02bd97c

URL: https://github.com/llvm/llvm-project/commit/96122b5b717c2b1a291d7298ac50b1daf02bd97c
DIFF: https://github.com/llvm/llvm-project/commit/96122b5b717c2b1a291d7298ac50b1daf02bd97c.diff

LOG: [C++20] [Modules] Introduce ForceCheckCXX20ModulesInputFiles options for
C++20 modules

Previously, we banned the check for input files from C++20 modules since
we thought the BMI from C++20 modules should be a standalone artifact.

However, during the recent experiment with clangd for modules, I find
it is necessary to tell whether or not a BMI is out-of-date by checking the
input files especially for language servers.

So this patch brings a header search option
ForceCheckCXX20ModulesInputFiles to allow the tools (concretly, clangd)
to check the input files from BMI.

Added: 
    clang/test/Modules/cxx20-force-check-input.cppm

Modified: 
    clang/include/clang/Driver/Options.td
    clang/include/clang/Lex/HeaderSearchOptions.h
    clang/lib/Frontend/ASTUnit.cpp
    clang/lib/Serialization/ASTReader.cpp

Removed: 
    


################################################################################
diff  --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index b29e2e53f938544..4bc292c1fa1620c 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -2906,6 +2906,11 @@ def fvalidate_ast_input_files_content:
            " Files with mismatching mtime's are considered valid"
            " if both contents is identical">,
   MarshallingInfoFlag<HeaderSearchOpts<"ValidateASTInputFilesContent">>;
+def fforce_check_cxx20_modules_input_files:
+  Flag <["-"], "fforce-check-cxx20-modules-input-files">,
+  Group<f_Group>, Visibility<[ClangOption, CC1Option]>,
+  HelpText<"Check the input source files from C++20 modules explicitly">,
+  MarshallingInfoFlag<HeaderSearchOpts<"ForceCheckCXX20ModulesInputFiles">>;
 def fmodules_validate_input_files_content:
   Flag <["-"], "fmodules-validate-input-files-content">,
   Group<f_Group>, Flags<[NoXarchOption]>,

diff  --git a/clang/include/clang/Lex/HeaderSearchOptions.h b/clang/include/clang/Lex/HeaderSearchOptions.h
index 6436a9b3bde20a2..126659f3ac00223 100644
--- a/clang/include/clang/Lex/HeaderSearchOptions.h
+++ b/clang/include/clang/Lex/HeaderSearchOptions.h
@@ -211,6 +211,9 @@ class HeaderSearchOptions {
   // validate consistency.
   unsigned ValidateASTInputFilesContent : 1;
 
+  // Whether the input files from C++20 Modules should be checked.
+  unsigned ForceCheckCXX20ModulesInputFiles : 1;
+
   /// Whether the module includes debug information (-gmodules).
   unsigned UseDebugInfo : 1;
 
@@ -233,7 +236,8 @@ class HeaderSearchOptions {
         UseStandardCXXIncludes(true), UseLibcxx(false), Verbose(false),
         ModulesValidateOncePerBuildSession(false),
         ModulesValidateSystemHeaders(false),
-        ValidateASTInputFilesContent(false), UseDebugInfo(false),
+        ValidateASTInputFilesContent(false),
+        ForceCheckCXX20ModulesInputFiles(false), UseDebugInfo(false),
         ModulesValidateDiagnosticOptions(true), ModulesHashContent(false),
         ModulesStrictContextHash(false) {}
 

diff  --git a/clang/lib/Frontend/ASTUnit.cpp b/clang/lib/Frontend/ASTUnit.cpp
index a4753f525d9de2d..167db521a890cd9 100644
--- a/clang/lib/Frontend/ASTUnit.cpp
+++ b/clang/lib/Frontend/ASTUnit.cpp
@@ -550,12 +550,16 @@ class ASTInfoCollector : public ASTReaderListener {
   bool ReadHeaderSearchOptions(const HeaderSearchOptions &HSOpts,
                                StringRef SpecificModuleCachePath,
                                bool Complain) override {
-    // Preserve previously set header search paths.
+    // llvm::SaveAndRestore doesn't support bit field.
+    auto ForceCheckCXX20ModulesInputFiles =
+        this->HSOpts.ForceCheckCXX20ModulesInputFiles;
     llvm::SaveAndRestore X(this->HSOpts.UserEntries);
     llvm::SaveAndRestore Y(this->HSOpts.SystemHeaderPrefixes);
     llvm::SaveAndRestore Z(this->HSOpts.VFSOverlayFiles);
 
     this->HSOpts = HSOpts;
+    this->HSOpts.ForceCheckCXX20ModulesInputFiles =
+        ForceCheckCXX20ModulesInputFiles;
 
     return false;
   }

diff  --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index 8ece979f2408e4d..576da09095002b0 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -2428,6 +2428,16 @@ InputFile ASTReader::getInputFile(ModuleFile &F, unsigned ID, bool Complain) {
   // For standard C++ modules, we don't need to check the inputs.
   bool SkipChecks = F.StandardCXXModule;
 
+  const HeaderSearchOptions &HSOpts =
+      PP.getHeaderSearchInfo().getHeaderSearchOpts();
+
+  // The option ForceCheckCXX20ModulesInputFiles is only meaningful for C++20
+  // modules.
+  if (F.StandardCXXModule && HSOpts.ForceCheckCXX20ModulesInputFiles) {
+    SkipChecks = false;
+    Overridden = false;
+  }
+
   OptionalFileEntryRefDegradesToFileEntryPtr File = OptionalFileEntryRef(
       expectedToOptional(FileMgr.getFileRef(Filename, /*OpenFile=*/false)));
 

diff  --git a/clang/test/Modules/cxx20-force-check-input.cppm b/clang/test/Modules/cxx20-force-check-input.cppm
new file mode 100644
index 000000000000000..4611f8f7cafa17e
--- /dev/null
+++ b/clang/test/Modules/cxx20-force-check-input.cppm
@@ -0,0 +1,33 @@
+// RUN: rm -rf %t
+// RUN: split-file %s %t
+//
+// RUN: %clang_cc1 -std=c++20 -triple %itanium_abi_triple \
+// RUN:     %t/a.cppm -emit-module-interface -o %t/a.pcm
+//
+// RUN: echo "inline int bar = 46;" >> %t/foo.h
+// RUNX: %clang_cc1 -std=c++20 -triple %itanium_abi_triple \
+// RUNX:     %t/use.cpp -fmodule-file=a=%t/a.pcm -verify -fsyntax-only
+// RUNX: %clang_cc1 -std=c++20 -triple %itanium_abi_triple \
+// RUNX:     %t/a.pcm -emit-llvm -o - | FileCheck %t/a.ll
+//
+// RUN: echo "export int var = 43;" >> %t/a.cppm
+// RUNX: %clang_cc1 -std=c++20 -triple %itanium_abi_triple \
+// RUNX:     %t/use.cpp -fmodule-file=a=%t/a.pcm -verify -fsyntax-only
+// RUNX: %clang_cc1 -std=c++20 -triple %itanium_abi_triple \
+// RUNX:     %t/a.pcm -emit-llvm -o - | FileCheck %t/a.ll
+//
+// RUN: not %clang_cc1 -std=c++20 -triple %itanium_abi_triple \
+// RUN:     -fforce-check-cxx20-modules-input-files %t/a.pcm \
+// RUN:     -emit-llvm -o -  2>&1 | FileCheck %t/a.cppm -check-prefix=CHECK-FAILURE
+
+//--- foo.h
+inline int foo = 43;
+
+//--- a.cppm
+// expected-no-diagnostics
+module;
+#include "foo.h"
+export module a;
+export using ::foo;
+
+// CHECK-FAILURE: fatal error:{{.*}}a.cppm' has been modified since the AST file {{.*}}was built