[clang] [clang] Make `-fvisibility={}` and `-ftype-visibility={}` benign options. (PR #71985)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Juergen Ributzka (ributzka)

<details>
<summary>Changes</summary>

Both options do not affect the AST content that is serialized into the PCM. This
commit includes the following changes:

1.) Mark `-fvisibility={}` and `-ftype-visibility={}` as benign options. That
    means they are no longer considered part of the module hash, which can
    reduce the number of module variants.

2.) Add a test to clang-scan-deps to ensure only one module is build, even if
    the above mentioned options are used.

This fixes rdar://118246054.


---
Full diff: https://github.com/llvm/llvm-project/pull/71985.diff


2 Files Affected:

- (modified) clang/include/clang/Basic/LangOptions.def (+2-2) 
- (added) clang/test/ClangScanDeps/strip-visibility.c (+59) 


``````````diff
diff --git a/clang/include/clang/Basic/LangOptions.def b/clang/include/clang/Basic/LangOptions.def
index c541ccefdd5fbe1..6ad6ccbe4a78c5f 100644
--- a/clang/include/clang/Basic/LangOptions.def
+++ b/clang/include/clang/Basic/LangOptions.def
@@ -349,9 +349,9 @@ LANGOPT(
     "type's inheritance model would be determined under the Microsoft ABI")
 
 ENUM_LANGOPT(GC, GCMode, 2, NonGC, "Objective-C Garbage Collection mode")
-ENUM_LANGOPT(ValueVisibilityMode, Visibility, 3, DefaultVisibility,
+BENIGN_ENUM_LANGOPT(ValueVisibilityMode, Visibility, 3, DefaultVisibility,
              "default visibility for functions and variables [-fvisibility]")
-ENUM_LANGOPT(TypeVisibilityMode, Visibility, 3, DefaultVisibility,
+BENIGN_ENUM_LANGOPT(TypeVisibilityMode, Visibility, 3, DefaultVisibility,
              "default visibility for types [-ftype-visibility]")
 LANGOPT(SetVisibilityForExternDecls, 1, 0,
         "apply global symbol visibility to external declarations without an explicit visibility")
diff --git a/clang/test/ClangScanDeps/strip-visibility.c b/clang/test/ClangScanDeps/strip-visibility.c
new file mode 100644
index 000000000000000..3c8de700b12bab1
--- /dev/null
+++ b/clang/test/ClangScanDeps/strip-visibility.c
@@ -0,0 +1,59 @@
+// RUN: rm -rf %t
+// RUN: split-file %s %t
+// RUN: sed -e "s|DIR|%/t|g" %t/cdb.json.template > %t/cdb.json
+
+// RUN: clang-scan-deps -compilation-database %t/cdb.json -format experimental-full -mode preprocess-dependency-directives > %t/result.txt
+
+// RUN: FileCheck %s -input-file %t/result.txt
+
+// Verify that there's a single version of module A.
+
+// CHECK:        "modules": [
+// CHECK-NEXT:     {
+// CHECK:            "command-line": [
+// CHECK-NOT:          "-fvisibility="
+// CHECK-NOT:          "-ftype-visibility="
+// CHECK:            ]
+// CHECK:            "name": "A"
+// CHECK:          }
+// CHECK-NOT:        "name": "A"
+// CHECK:        "translation-units"
+
+//--- cdb.json.template
+[
+  {
+    "directory": "DIR",
+    "command": "clang -Imodules/A -fmodules -fmodules-cache-path=DIR/module-cache -fimplicit-modules -fimplicit-module-maps -fsyntax-only DIR/t1.c",
+    "file": "DIR/t1.c"
+  },
+  {
+    "directory": "DIR",
+    "command": "clang -Imodules/A -fmodules -fmodules-cache-path=DIR/module-cache -fimplicit-modules -fimplicit-module-maps -fvisibility=hidden -fsyntax-only DIR/t2.c",
+    "file": "DIR/t2.c"
+  },
+  {
+    "directory": "DIR",
+    "command": "clang -Imodules/A -fmodules -fmodules-cache-path=DIR/module-cache -fimplicit-modules -fimplicit-module-maps -fvisibility=hidden -fvisibility-ms-compat -fsyntax-only DIR/t3.c",
+    "file": "DIR/t3.c"
+  }
+]
+
+//--- modules/A/module.modulemap
+
+module A {
+  umbrella header "A.h"
+}
+
+//--- modules/A/A.h
+
+typedef int A_t;
+extern int a(void);
+
+//--- t1.c
+#include "A.h"
+
+//--- t2.c
+#include "A.h"
+
+//--- t3.c
+#include "A.h"

``````````

</details>


https://github.com/llvm/llvm-project/pull/71985