[clang] [clang][NFC] Improve const-correctness in `SourceManager` (PR #92436)

[Vlad Serebrennikov via cfe-commits]

https://github.com/Endilll created https://github.com/llvm/llvm-project/pull/92436

This patch adds several const-qualified variants of existing member functions to `SourceManager`.
I started with removing const qualification from `setNumCreatedFIDsForFileID`, and removing `const_cast` in the body of this function, as I think it doesn't make sense to const-qualify setters.

>From d794398b304e1f20dcd61e45ae034195563494ee Mon Sep 17 00:00:00 2001
From: Vlad Serebrennikov <serebrennikov.vladislav at gmail.com>
Date: Thu, 16 May 2024 21:04:39 +0300
Subject: [PATCH] [clang][NFC] Improve const-correctness in `SourceManager`

---
 clang/include/clang/Basic/SourceManager.h | 44 +++++++++++++++++++++--
 clang/lib/Basic/SourceManager.cpp         |  4 +++
 2 files changed, 45 insertions(+), 3 deletions(-)

diff --git a/clang/include/clang/Basic/SourceManager.h b/clang/include/clang/Basic/SourceManager.h
index 5258bab584f49..ce33423551039 100644
--- a/clang/include/clang/Basic/SourceManager.h
+++ b/clang/include/clang/Basic/SourceManager.h
@@ -497,6 +497,10 @@ class SLocEntry {
   bool isFile() const { return !isExpansion(); }
 
   const FileInfo &getFile() const {
+    return const_cast<SLocEntry *>(this)->getFile();
+  }
+
+  FileInfo &getFile() {
     assert(isFile() && "Not a file SLocEntry!");
     return File;
   }
@@ -1120,12 +1124,12 @@ class SourceManager : public RefCountedBase<SourceManager> {
   /// Set the number of FileIDs (files and macros) that were created
   /// during preprocessing of \p FID, including it.
   void setNumCreatedFIDsForFileID(FileID FID, unsigned NumFIDs,
-                                  bool Force = false) const {
+                                  bool Force = false) {
     auto *Entry = getSLocEntryForFile(FID);
     if (!Entry)
       return;
     assert((Force || Entry->getFile().NumCreatedFIDs == 0) && "Already set!");
-    const_cast<SrcMgr::FileInfo &>(Entry->getFile()).NumCreatedFIDs = NumFIDs;
+    Entry->getFile().NumCreatedFIDs = NumFIDs;
   }
 
   //===--------------------------------------------------------------------===//
@@ -1730,6 +1734,11 @@ class SourceManager : public RefCountedBase<SourceManager> {
 
   /// Get a local SLocEntry. This is exposed for indexing.
   const SrcMgr::SLocEntry &getLocalSLocEntry(unsigned Index) const {
+    return const_cast<SourceManager *>(this)->getLocalSLocEntry(Index);
+  }
+
+  /// Get a local SLocEntry. This is exposed for indexing.
+  SrcMgr::SLocEntry &getLocalSLocEntry(unsigned Index) {
     assert(Index < LocalSLocEntryTable.size() && "Invalid index");
     return LocalSLocEntryTable[Index];
   }
@@ -1740,6 +1749,13 @@ class SourceManager : public RefCountedBase<SourceManager> {
   /// Get a loaded SLocEntry. This is exposed for indexing.
   const SrcMgr::SLocEntry &getLoadedSLocEntry(unsigned Index,
                                               bool *Invalid = nullptr) const {
+    return const_cast<SourceManager *>(this)->getLoadedSLocEntry(Index,
+                                                                 Invalid);
+  }
+
+  /// Get a loaded SLocEntry. This is exposed for indexing.
+  SrcMgr::SLocEntry &getLoadedSLocEntry(unsigned Index,
+                                        bool *Invalid = nullptr) {
     assert(Index < LoadedSLocEntryTable.size() && "Invalid index");
     if (SLocEntryLoaded[Index])
       return LoadedSLocEntryTable[Index];
@@ -1748,6 +1764,10 @@ class SourceManager : public RefCountedBase<SourceManager> {
 
   const SrcMgr::SLocEntry &getSLocEntry(FileID FID,
                                         bool *Invalid = nullptr) const {
+    return const_cast<SourceManager *>(this)->getSLocEntry(FID, Invalid);
+  }
+
+  SrcMgr::SLocEntry &getSLocEntry(FileID FID, bool *Invalid = nullptr) {
     if (FID.ID == 0 || FID.ID == -1) {
       if (Invalid) *Invalid = true;
       return LocalSLocEntryTable[0];
@@ -1821,14 +1841,23 @@ class SourceManager : public RefCountedBase<SourceManager> {
   SrcMgr::ContentCache &getFakeContentCacheForRecovery() const;
 
   const SrcMgr::SLocEntry &loadSLocEntry(unsigned Index, bool *Invalid) const;
+  SrcMgr::SLocEntry &loadSLocEntry(unsigned Index, bool *Invalid);
 
   const SrcMgr::SLocEntry *getSLocEntryOrNull(FileID FID) const {
+    return const_cast<SourceManager *>(this)->getSLocEntryOrNull(FID);
+  }
+
+  SrcMgr::SLocEntry *getSLocEntryOrNull(FileID FID) {
     bool Invalid = false;
-    const SrcMgr::SLocEntry &Entry = getSLocEntry(FID, &Invalid);
+    SrcMgr::SLocEntry &Entry = getSLocEntry(FID, &Invalid);
     return Invalid ? nullptr : &Entry;
   }
 
   const SrcMgr::SLocEntry *getSLocEntryForFile(FileID FID) const {
+    return const_cast<SourceManager *>(this)->getSLocEntryForFile(FID);
+  }
+
+  SrcMgr::SLocEntry *getSLocEntryForFile(FileID FID) {
     if (auto *Entry = getSLocEntryOrNull(FID))
       if (Entry->isFile())
         return Entry;
@@ -1839,6 +1868,10 @@ class SourceManager : public RefCountedBase<SourceManager> {
   /// Invalid will not be modified for Local IDs.
   const SrcMgr::SLocEntry &getSLocEntryByID(int ID,
                                             bool *Invalid = nullptr) const {
+    return const_cast<SourceManager *>(this)->getSLocEntryByID(ID, Invalid);
+  }
+
+  SrcMgr::SLocEntry &getSLocEntryByID(int ID, bool *Invalid = nullptr) {
     assert(ID != -1 && "Using FileID sentinel value");
     if (ID < 0)
       return getLoadedSLocEntryByID(ID, Invalid);
@@ -1847,6 +1880,11 @@ class SourceManager : public RefCountedBase<SourceManager> {
 
   const SrcMgr::SLocEntry &
   getLoadedSLocEntryByID(int ID, bool *Invalid = nullptr) const {
+    return const_cast<SourceManager *>(this)->getLoadedSLocEntryByID(ID,
+                                                                     Invalid);
+  }
+
+  SrcMgr::SLocEntry &getLoadedSLocEntryByID(int ID, bool *Invalid = nullptr) {
     return getLoadedSLocEntry(static_cast<unsigned>(-ID - 2), Invalid);
   }
 
diff --git a/clang/lib/Basic/SourceManager.cpp b/clang/lib/Basic/SourceManager.cpp
index 37734d3b10e78..afdb5b0e92d64 100644
--- a/clang/lib/Basic/SourceManager.cpp
+++ b/clang/lib/Basic/SourceManager.cpp
@@ -431,6 +431,10 @@ ContentCache &SourceManager::createMemBufferContentCache(
 
 const SrcMgr::SLocEntry &SourceManager::loadSLocEntry(unsigned Index,
                                                       bool *Invalid) const {
+  return const_cast<SourceManager *>(this)->loadSLocEntry(Index, Invalid);
+}
+
+SrcMgr::SLocEntry &SourceManager::loadSLocEntry(unsigned Index, bool *Invalid) {
   assert(!SLocEntryLoaded[Index]);
   if (ExternalSLocEntries->ReadSLocEntry(-(static_cast<int>(Index) + 2))) {
     if (Invalid)