From: David Majnemer <david.majnemer@gmail.com>
Date: Tue, 5 Nov 2013 09:30:17 +0000 (+0000)
Subject: Lex: Require that '#' be followed by a macro parameter name when preceded by '##'
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=974cbc5e43c4aeb9bf4a6bb7ed2718a20a910437;p=clang

Lex: Require that '#' be followed by a macro parameter name when preceded by '##'

After lexing a '##', we would look ahead and check to see if it was
followed by '__VA_ARGS__'.  After doing so, we would then go ahead and
lex the token.

However we would fail in the case where the '##' was followed by a '#'
followed by an identifier because we would have lexed the '#' separately
from the identifier, bypassing our parameter validation logic.

Instead, lex the tokens coming after the '##' later.

This fixes PR17804.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@194059 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Lex/PPDirectives.cpp b/lib/Lex/PPDirectives.cpp
index a952b2ef1b..9ba65a57a8 100644
--- a/lib/Lex/PPDirectives.cpp
+++ b/lib/Lex/PPDirectives.cpp
@@ -2005,13 +2005,8 @@ void Preprocessor::HandleDefineDirective(Token &DefineTok,
             MI->getReplacementToken(NumTokens-1).is(tok::comma))
           MI->setHasCommaPasting();
 
-        // Things look ok, add the '##' and param name tokens to the macro.
+        // Things look ok, add the '##' token to the macro.
         MI->AddTokenToBody(LastTok);
-        MI->AddTokenToBody(Tok);
-        LastTok = Tok;
-
-        // Get the next token of the macro.
-        LexUnexpandedToken(Tok);
         continue;
       }
 
diff --git a/test/Preprocessor/macro_paste_bad.c b/test/Preprocessor/macro_paste_bad.c
index 0a028a4468..211465433b 100644
--- a/test/Preprocessor/macro_paste_bad.c
+++ b/test/Preprocessor/macro_paste_bad.c
@@ -32,3 +32,5 @@ XX     // expected-error {{attempt to use a poisoned identifier}}
 #define VA __VA_ ## ARGS__
 int VA;   // expected-warning {{__VA_ARGS__ can only appear in the expansion of a C99 variadic macro}}
 
+#define LOG_ON_ERROR(lvl) ::X x## #__LINE__; // expected-error {{'#' is not followed by a macro parameter}}
+LOG_ON_ERROR(0);