Move SystemHeadersCoverage into llvm::coverage in CoverageMappingGen.h

Part of #97952

Author: chapuni

clang/lib/CodeGen/CodeGenPGO.cpp

@@ -32,8 +32,6 @@ static llvm::cl::opt<bool>
                          llvm::cl::desc("Enable value profiling"),
                          llvm::cl::Hidden, llvm::cl::init(false));
 
-extern llvm::cl::opt<bool> SystemHeadersCoverage;
-
 using namespace clang;
 using namespace CodeGen;
 
@@ -1118,7 +1116,7 @@ bool CodeGenPGO::skipRegionMappingForDecl(const Decl *D) {
   // Don't map the functions in system headers.
   const auto &SM = CGM.getContext().getSourceManager();
   auto Loc = D->getBody()->getBeginLoc();
-  return !SystemHeadersCoverage && SM.isInSystemHeader(Loc);
+  return !llvm::coverage::SystemHeadersCoverage && SM.isInSystemHeader(Loc);
 }
 
 void CodeGenPGO::emitCounterRegionMapping(const Decl *D) {

clang/lib/CodeGen/CoverageMappingGen.cpp

@@ -46,10 +46,12 @@ static llvm::cl::opt<bool> EmptyLineCommentCoverage(
                    "disable it on test)"),
     llvm::cl::init(true), llvm::cl::Hidden);
 
-llvm::cl::opt<bool> SystemHeadersCoverage(
+namespace llvm::coverage {
+cl::opt<bool> SystemHeadersCoverage(
     "system-headers-coverage",
-    llvm::cl::desc("Enable collecting coverage from system headers"),
-    llvm::cl::init(false), llvm::cl::Hidden);
+    cl::desc("Enable collecting coverage from system headers"), cl::init(false),
+    cl::Hidden);
+}
 
 using namespace clang;
 using namespace CodeGen;

clang/lib/CodeGen/CoverageMappingGen.h

@@ -19,8 +19,13 @@
 #include "clang/Lex/Preprocessor.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/IR/GlobalValue.h"
+#include "llvm/Support/CommandLine.h"
 #include "llvm/Support/raw_ostream.h"
 
+namespace llvm::coverage {
+extern cl::opt<bool> SystemHeadersCoverage;
+}
+
 namespace clang {
 
 class LangOptions;