Make LookUpIdentifierInfo const. This makes the Identifiers table mutable and is

a little fuzzy, but conceptually it's just uniquing the identifier.

Chris, please review. I debated splitting into const/non-const versions where
the const one propogated constness to the resulting IdentifierInfo*.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@86106 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Lex/Preprocessor.h

@@ -96,7 +96,7 @@ class Preprocessor {
 
   /// Identifiers - This is mapping/lookup information for all identifiers in
   /// the program, including program keywords.
-  IdentifierTable Identifiers;
+  mutable IdentifierTable Identifiers;
 
   /// Selectors - This table contains all the selectors in the program. Unlike
   /// IdentifierTable above, this table *isn't* populated by the preprocessor.
@@ -296,7 +296,7 @@ public:
   /// pointers is preferred unless the identifier is already available as a
   /// string (this avoids allocation and copying of memory to construct an
   /// std::string).
-  IdentifierInfo *getIdentifierInfo(llvm::StringRef Name) {
+  IdentifierInfo *getIdentifierInfo(llvm::StringRef Name) const {
     return &Identifiers.get(Name);
   }
 
@@ -579,7 +579,7 @@ public:
   /// LookUpIdentifierInfo - Given a tok::identifier token, look up the
   /// identifier information for the token and install it into the token.
   IdentifierInfo *LookUpIdentifierInfo(Token &Identifier,
-                                       const char *BufPtr = 0);
+                                       const char *BufPtr = 0) const;
 
   /// HandleIdentifier - This callback is invoked when the lexer reads an
   /// identifier and has filled in the tokens IdentifierInfo member.  This

lib/Lex/Preprocessor.cpp

@@ -401,7 +401,7 @@ void Preprocessor::EnterMainSourceFile() {
 /// LookUpIdentifierInfo - Given a tok::identifier token, look up the
 /// identifier information for the token and install it into the token.
 IdentifierInfo *Preprocessor::LookUpIdentifierInfo(Token &Identifier,
-                                                   const char *BufPtr) {
+                                                   const char *BufPtr) const {
   assert(Identifier.is(tok::identifier) && "Not an identifier!");
   assert(Identifier.getIdentifierInfo() == 0 && "Identinfo already exists!");