[clang][NFC] Make HeaderSearch::suggestPathToFileForDiagnostics method const.

Author: hokein

clang/include/clang/Lex/HeaderSearch.h

@@ -867,7 +867,7 @@ class HeaderSearch {
   ///        path is relative to a system header directory.
   std::string suggestPathToFileForDiagnostics(const FileEntry *File,
                                               llvm::StringRef MainFile,
-                                              bool *IsSystem = nullptr);
+                                              bool *IsSystem = nullptr) const;
 
   /// Suggest a path by which the specified file could be found, for use in
   /// diagnostics to suggest a #include. Returned path will only contain forward
@@ -881,7 +881,7 @@ class HeaderSearch {
   std::string suggestPathToFileForDiagnostics(llvm::StringRef File,
                                               llvm::StringRef WorkingDir,
                                               llvm::StringRef MainFile,
-                                              bool *IsSystem = nullptr);
+                                              bool *IsSystem = nullptr) const;
 
   void PrintStats();
 

clang/lib/Lex/HeaderSearch.cpp

@@ -1919,7 +1919,7 @@ void HeaderSearch::loadSubdirectoryModuleMaps(DirectoryLookup &SearchDir) {
 }
 
 std::string HeaderSearch::suggestPathToFileForDiagnostics(
-    const FileEntry *File, llvm::StringRef MainFile, bool *IsSystem) {
+    const FileEntry *File, llvm::StringRef MainFile, bool *IsSystem) const {
   // FIXME: We assume that the path name currently cached in the FileEntry is
   // the most appropriate one for this analysis (and that it's spelled the
   // same way as the corresponding header search path).
@@ -1929,7 +1929,7 @@ std::string HeaderSearch::suggestPathToFileForDiagnostics(
 
 std::string HeaderSearch::suggestPathToFileForDiagnostics(
     llvm::StringRef File, llvm::StringRef WorkingDir, llvm::StringRef MainFile,
-    bool *IsSystem) {
+    bool *IsSystem) const {
   using namespace llvm::sys;
 
   llvm::SmallString<32> FilePath = File;