[libclang] Get rid of relience on SourceManager member signature

[kadircet]

Summary

Libclang was enforcing a singature on SourceManager::getLocalSLocEntry
which isn't possible to satisfy as pointed out in
https://reviews.llvm.org/D80681#inline-751438.

This patch updates the libclang, hopefully without breaking API stability, to
not rely on member signature. To enable changing the signature in D82498.

[sammccall]

Regardless of the outcome on the other patch, I like this code better.

clang/tools/libclang/CIndexInclusionStack.cpp

 
 #include "CIndexer.h"
 #include "CXSourceLocation.h"
 #include "CXTranslationUnit.h"
 #include "clang/AST/DeclVisitor.h"
 #include "clang/Frontend/ASTUnit.h"
 using namespace clang;
 
-static void getInclusions(const SrcMgr::SLocEntry &(SourceManager::*Getter)(unsigned, bool*) const, unsigned n,
-                          CXTranslationUnit TU, CXInclusionVisitor CB,
-                          CXClientData clientData)
-{
+namespace {
+void getInclusions(bool IsLocal, unsigned n, CXTranslationUnit TU,
+                   CXInclusionVisitor CB, CXClientData clientData) {
   ASTUnit *CXXUnit = cxtu::getASTUnit(TU);
   SourceManager &SM = CXXUnit->getSourceManager();
   ASTContext &Ctx = CXXUnit->getASTContext();
   SmallVector<CXSourceLocation, 10> InclusionStack;
   const bool HasPreamble = SM.getPreambleFileID().isValid();
 
   for (unsigned i = 0 ; i < n ; ++i) {
     bool Invalid = false;
-    const SrcMgr::SLocEntry &SL = (SM.*Getter)(i, &Invalid);
-
+    const SrcMgr::SLocEntry &SL =
+        IsLocal ? SM.getLocalSLocEntry(i) : SM.getLoadedSLocEntry(i, &Invalid);
     if (!SL.isFile() || Invalid)
       continue;
 
     const SrcMgr::FileInfo &FI = SL.getFile();
     if (!FI.getContentCache()->OrigEntry)
       continue;
 
     // If this is the main file, and there is a preamble, skip this SLoc. The
for (unsigned i = 0 ; i < n ; ++i) {
     // If there is a preamble, the last entry is the "inclusion" of that
     // preamble into the main file, which has the bogus entry of main.c:1:1
     if (HasPreamble && !InclusionStack.empty())
       InclusionStack.pop_back();
 
     // Callback to the client.
     // FIXME: We should have a function to construct CXFiles.
     CB(static_cast<CXFile>(
            const_cast<FileEntry *>(FI.getContentCache()->OrigEntry)),
        InclusionStack.data(), InclusionStack.size(), clientData);
   }
 }
-
+} // namespace
 
 void clang_getInclusions(CXTranslationUnit TU, CXInclusionVisitor CB,
                          CXClientData clientData) {
   if (cxtu::isNotUsableTU(TU)) {
     LOG_BAD_TU(TU);
     return;
   }
 
   SourceManager &SM = cxtu::getASTUnit(TU)->getSourceManager();
   const unsigned n =  SM.local_sloc_entry_size();
 
   // In the case where all the SLocEntries are in an external source, traverse
   // those SLocEntries as well.  This is the case where we are looking
   // at the inclusion stack of an AST/PCH file. Also, if we are not looking at
   // a AST/PCH file, but this file has a pre-compiled preamble, we also need
   // to look in that file.
   if (n == 1 || SM.getPreambleFileID().isValid()) {
-    getInclusions(&SourceManager::getLoadedSLocEntry,
-                  SM.loaded_sloc_entry_size(), TU, CB, clientData);
+    getInclusions(/*IsLocal=*/false, SM.loaded_sloc_entry_size(), TU, CB,
+                  clientData);
   }
 
   // Not a PCH/AST file. Note, if there is a preamble, it could still be that
   // there are #includes in this file (e.g. for any include after the first
   // declaration).
   if (n != 1)
-    getInclusions(&SourceManager::getLocalSLocEntry, n, TU, CB, clientData);
-
+    getInclusions(/*IsLocal=*/true, n, TU, CB, clientData);
 }