Handle standard libraries that miss out the space when defining the standard

literal operators. Also, for now, allow the proposed C++1y "il", "i", and "if"
suffixes too. (Will revert the latter if LWG decides not to go ahead with that
change after all.)

llvm-svn: 191274

2 files changed, 33 insertions, 6 deletions

diff --git a/clang/lib/Lex/Lexer.cpp b/clang/lib/Lex/Lexer.cpp
index e6b6b1fe1c1..d8a5160e95d 100644
--- a/clang/lib/Lex/Lexer.cpp
+++ b/clang/lib/Lex/Lexer.cpp
@@ -29,6 +29,7 @@
 #include "clang/Basic/SourceManager.h"
 #include "clang/Lex/CodeCompletionHandler.h"
 #include "clang/Lex/LexDiagnostic.h"
+#include "clang/Lex/LiteralSupport.h"
 #include "clang/Lex/Preprocessor.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringExtras.h"
@@ -1638,12 +1639,33 @@ const char *Lexer::LexUDSuffix(Token &Result, const char *CurPtr,
     bool IsUDSuffix = false;
     if (C == '_')
       IsUDSuffix = true;
-    else if (IsStringLiteral && C == 's' && getLangOpts().CPlusPlus1y) {
-      // In C++1y, "s" is a valid ud-suffix for a string literal.
-      unsigned NextSize;
-      if (!isIdentifierBody(getCharAndSizeNoWarn(CurPtr + Size, NextSize,
-                                                 getLangOpts())))
-        IsUDSuffix = true;
+    else if (IsStringLiteral && getLangOpts().CPlusPlus1y) {
+      // In C++1y, we need to look ahead a few characters to see if this is a
+      // valid suffix for a string literal or a numeric literal (this could be
+      // the 'operator""if' defining a numeric literal operator).
+      const int MaxStandardSuffixLength = 3;
+      char Buffer[MaxStandardSuffixLength] = { C };
+      unsigned Consumed = Size;
+      unsigned Chars = 1;
+      while (true) {
+        unsigned NextSize;
+        char Next = getCharAndSizeNoWarn(CurPtr + Consumed, NextSize,
+                                         getLangOpts());
+        if (!isIdentifierBody(Next)) {
+          // End of suffix. Check whether this is on the whitelist.
+          IsUDSuffix = (Chars == 1 && Buffer[0] == 's') ||
+                       NumericLiteralParser::isValidUDSuffix(
+                           getLangOpts(), StringRef(Buffer, Chars));
+          break;
+        }
+
+        if (Chars == MaxStandardSuffixLength)
+          // Too long: can't be a standard suffix.
+          break;
+
+        Buffer[Chars++] = Next;
+        Consumed += NextSize;
+      }
     }
 
     if (!IsUDSuffix) {
diff --git a/clang/lib/Lex/LiteralSupport.cpp b/clang/lib/Lex/LiteralSupport.cpp
index c637c388192..893141d5957 100644
--- a/clang/lib/Lex/LiteralSupport.cpp
+++ b/clang/lib/Lex/LiteralSupport.cpp
@@ -604,6 +604,9 @@ NumericLiteralParser::NumericLiteralParser(StringRef TokSpelling,
           break;
         }
       }
+      // "i", "if", and "il" are user-defined suffixes in C++1y.
+      if (PP.getLangOpts().CPlusPlus1y && *s == 'i')
+        break;
       // fall through.
     case 'j':
     case 'J':
@@ -665,9 +668,11 @@ bool NumericLiteralParser::isValidUDSuffix(const LangOptions &LangOpts,
     return false;
 
   // In C++1y, "s", "h", "min", "ms", "us", and "ns" are used in the library.
+  // Per tweaked N3660, "il", "i", and "if" are also used in the library.
   return llvm::StringSwitch<bool>(Suffix)
       .Cases("h", "min", "s", true)
       .Cases("ms", "us", "ns", true)
+      .Cases("il", "i", "if", true)
       .Default(false);
 }