[clang][modules] Strip LLVM options (#75405)

Currently, the dep scanner does not remove LLVM options from the
argument list.
Since LLVM options shouldn't affect the AST, it is safe to remove them
all.

clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp

@@ -119,6 +119,8 @@ makeCommonInvocationForModuleBuild(CompilerInvocation CI) {
   // units.
   CI.getFrontendOpts().Inputs.clear();
   CI.getFrontendOpts().OutputFile.clear();
+  // LLVM options are not going to affect the AST
+  CI.getFrontendOpts().LLVMArgs.clear();
 
   // TODO: Figure out better way to set options to their default value.
   CI.getCodeGenOpts().MainFileName.clear();

clang/test/ClangScanDeps/strip-llvm-args.m

@@ -0,0 +1,46 @@
+// RUN: rm -rf %t
+// RUN: split-file %s %t
+// RUN: sed -e "s|DIR|%/t|g" %t/cdb1.json.template > %t/cdb1.json
+
+// RUN: clang-scan-deps -compilation-database %t/cdb1.json -format experimental-full > %t/result1.txt
+// RUN: FileCheck %s -input-file %t/result1.txt
+
+// CHECK:        "modules": [
+// CHECK-NEXT:     {
+// CHECK:            "command-line": [
+// CHECK-NOT:          "-mllvm"
+// CHECK:            ]
+// CHECK:            "name": "A"
+// CHECK:          }
+// CHECK-NOT:        "name": "A"
+// CHECK:        "translation-units"
+
+//--- cdb1.json.template
+[
+  {
+    "directory": "DIR",
+    "command": "clang -Imodules/A -fmodules -fmodules-cache-path=DIR/module-cache -fimplicit-modules -fimplicit-module-maps -fsyntax-only DIR/t1.m",
+    "file": "DIR/t1.m"
+  },
+  {
+    "directory": "DIR",
+    "command": "clang -Imodules/A -fmodules -fmodules-cache-path=DIR/module-cache -fimplicit-modules -fimplicit-module-maps -mllvm -stackmap-version=2 -fsyntax-only DIR/t2.m",
+    "file": "DIR/t2.m"
+  }
+]
+
+//--- modules/A/module.modulemap
+
+module A {
+  umbrella header "A.h"
+}
+
+//--- modules/A/A.h
+
+typedef int A_t;
+
+//--- t1.m
+@import A;
+
+//--- t2.m
+@import A;