[clang] Make HeaderSearchOptions references const (#130825)

This PR makes the `HeaderSearchOptions` object referenced by
`HeaderSearch` constant. Depends on #130823.

Author: jansvoboda11

clang/include/clang/Lex/HeaderSearch.h

@@ -241,7 +241,7 @@ class HeaderSearch {
   friend SearchDirIterator;
 
   /// Header-search options used to initialize this header search.
-  std::shared_ptr<HeaderSearchOptions> HSOpts;
+  std::shared_ptr<const HeaderSearchOptions> HSOpts;
 
   /// Mapping from SearchDir to HeaderSearchOptions::UserEntries indices.
   llvm::DenseMap<unsigned, unsigned> SearchDirToHSEntry;
@@ -359,15 +359,15 @@ class HeaderSearch {
   void indexInitialHeaderMaps();
 
 public:
-  HeaderSearch(std::shared_ptr<HeaderSearchOptions> HSOpts,
+  HeaderSearch(std::shared_ptr<const HeaderSearchOptions> HSOpts,
                SourceManager &SourceMgr, DiagnosticsEngine &Diags,
                const LangOptions &LangOpts, const TargetInfo *Target);
   HeaderSearch(const HeaderSearch &) = delete;
   HeaderSearch &operator=(const HeaderSearch &) = delete;
 
   /// Retrieve the header-search options with which this header search
   /// was initialized.
-  HeaderSearchOptions &getHeaderSearchOpts() const { return *HSOpts; }
+  const HeaderSearchOptions &getHeaderSearchOpts() const { return *HSOpts; }
 
   FileManager &getFileMgr() const { return FileMgr; }
 

clang/lib/Frontend/CompilerInstance.cpp

@@ -631,7 +631,8 @@ IntrusiveRefCntPtr<ASTReader> CompilerInstance::createPCHExternalASTSource(
     ArrayRef<std::shared_ptr<DependencyCollector>> DependencyCollectors,
     void *DeserializationListener, bool OwnDeserializationListener,
     bool Preamble, bool UseGlobalModuleIndex) {
-  HeaderSearchOptions &HSOpts = PP.getHeaderSearchInfo().getHeaderSearchOpts();
+  const HeaderSearchOptions &HSOpts =
+      PP.getHeaderSearchInfo().getHeaderSearchOpts();
 
   IntrusiveRefCntPtr<ASTReader> Reader(new ASTReader(
       PP, ModCache, &Context, PCHContainerRdr, Extensions,

clang/lib/Frontend/FrontendActions.cpp

@@ -878,7 +878,8 @@ void DumpModuleInfoAction::ExecuteAction() {
 
   Preprocessor &PP = CI.getPreprocessor();
   DumpModuleInfoListener Listener(Out);
-  HeaderSearchOptions &HSOpts = PP.getHeaderSearchInfo().getHeaderSearchOpts();
+  const HeaderSearchOptions &HSOpts =
+      PP.getHeaderSearchInfo().getHeaderSearchOpts();
 
   // The FrontendAction::BeginSourceFile () method loads the AST so that much
   // of the information is already available and modules should have been

clang/lib/Lex/HeaderSearch.cpp

@@ -80,7 +80,7 @@ HeaderFileInfo::getControllingMacro(ExternalPreprocessorSource *External) {
 
 ExternalHeaderFileInfoSource::~ExternalHeaderFileInfoSource() = default;
 
-HeaderSearch::HeaderSearch(std::shared_ptr<HeaderSearchOptions> HSOpts,
+HeaderSearch::HeaderSearch(std::shared_ptr<const HeaderSearchOptions> HSOpts,
                            SourceManager &SourceMgr, DiagnosticsEngine &Diags,
                            const LangOptions &LangOpts,
                            const TargetInfo *Target)

clang/lib/Serialization/ASTReader.cpp

@@ -4901,7 +4901,8 @@ ASTReader::ASTReadResult ASTReader::ReadAST(StringRef FileName, ModuleKind Type,
     }
   }
 
-  HeaderSearchOptions &HSOpts = PP.getHeaderSearchInfo().getHeaderSearchOpts();
+  const HeaderSearchOptions &HSOpts =
+      PP.getHeaderSearchInfo().getHeaderSearchOpts();
   if (HSOpts.ModulesValidateOncePerBuildSession) {
     // Now we are certain that the module and all modules it depends on are
     // up-to-date. For implicitly-built module files, ensure the corresponding