[cfe-commits] r167613 - in /cfe/trunk: lib/Lex/TokenLexer.cpp test/Preprocessor/macro_fn_comma_swallow2.c
Andy Gibbs
andyg1001 at hotmail.co.uk
Fri Nov 9 05:24:31 PST 2012
Author: andyg
Date: Fri Nov 9 07:24:30 2012
New Revision: 167613
URL: http://llvm.org/viewvc/llvm-project?rev=167613&view=rev
Log:
Improved support for removing the comma preceding __VA_ARGS__ where __VA_ARGS__
is empty in a variadic macro expansion. This fixes a divergence in support for
the ", ## __VA_ARGS__" GCC extension which differed in behaviour when in strict
C99 mode (note: there is no change in behaviour has been made in the gnu99 mode
that clang uses by default). In addition, there is improved support for the
Microsoft alternative extension ", __VA_ARGS__".
Added:
cfe/trunk/test/Preprocessor/macro_fn_comma_swallow2.c
Modified:
cfe/trunk/lib/Lex/TokenLexer.cpp
Modified: cfe/trunk/lib/Lex/TokenLexer.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Lex/TokenLexer.cpp?rev=167613&r1=167612&r2=167613&view=diff
==============================================================================
--- cfe/trunk/lib/Lex/TokenLexer.cpp (original)
+++ cfe/trunk/lib/Lex/TokenLexer.cpp Fri Nov 9 07:24:30 2012
@@ -119,6 +119,55 @@
if (ActualArgs) ActualArgs->destroy(PP);
}
+/// Remove comma ahead of __VA_ARGS__, if present, according to compiler dialect
+/// settings. Returns true if the comma is removed.
+static bool MaybeRemoveCommaBeforeVaArgs(SmallVector<Token, 128> &ResultToks,
+ bool &NextTokGetsSpace,
+ bool HasPasteOperator,
+ MacroInfo *Macro, unsigned MacroArgNo,
+ Preprocessor &PP) {
+ // Is the macro argument __VA_ARGS__?
+ if (!Macro->isVariadic() || MacroArgNo != Macro->getNumArgs()-1)
+ return false;
+
+ // In Microsoft-compatibility mode, a comma is removed in the expansion
+ // of " ... , __VA_ARGS__ " if __VA_ARGS__ is empty. This extension is
+ // not supported by gcc.
+ if (!HasPasteOperator && !PP.getLangOpts().MicrosoftMode)
+ return false;
+
+ // GCC removes the comma in the expansion of " ... , ## __VA_ARGS__ " if
+ // __VA_ARGS__ is empty, but not in strict C99 mode where there are no
+ // named arguments, where it remains. In all other modes, including C99
+ // with GNU extensions, it is removed regardless of named arguments.
+ // Microsoft also appears to support this extension, unofficially.
+ if (PP.getLangOpts().C99 && !PP.getLangOpts().GNUMode
+ && Macro->getNumArgs() < 2)
+ return false;
+
+ // Is a comma available to be removed?
+ if (ResultToks.empty() || !ResultToks.back().is(tok::comma))
+ return false;
+
+ // Issue an extension diagnostic for the paste operator.
+ if (HasPasteOperator)
+ PP.Diag(ResultToks.back().getLocation(), diag::ext_paste_comma);
+
+ // Remove the comma.
+ ResultToks.pop_back();
+
+ // If the comma was right after another paste (e.g. "X##,##__VA_ARGS__"),
+ // then removal of the comma should produce a placemarker token (in C99
+ // terms) which we model by popping off the previous ##, giving us a plain
+ // "X" when __VA_ARGS__ is empty.
+ if (!ResultToks.empty() && ResultToks.back().is(tok::hashhash))
+ ResultToks.pop_back();
+
+ // Never add a space, even if the comma, ##, or arg had a space.
+ NextTokGetsSpace = false;
+ return true;
+}
+
/// Expand the arguments of a function-like macro so that we can quickly
/// return preexpanded tokens from Tokens.
void TokenLexer::ExpandFunctionArguments() {
@@ -199,6 +248,14 @@
!ResultToks.empty() && ResultToks.back().is(tok::hashhash);
bool PasteAfter = i+1 != e && Tokens[i+1].is(tok::hashhash);
+ // In Microsoft mode, remove the comma before __VA_ARGS__ to ensure there
+ // are no trailing commas if __VA_ARGS__ is empty.
+ if (!PasteBefore && ActualArgs->isVarargsElidedUse() &&
+ MaybeRemoveCommaBeforeVaArgs(ResultToks, NextTokGetsSpace,
+ /*HasPasteOperator=*/false,
+ Macro, ArgNo, PP))
+ continue;
+
// If it is not the LHS/RHS of a ## operator, we must pre-expand the
// argument and substitute the expanded tokens into the result. This is
// C99 6.10.3.1p1.
@@ -321,23 +378,13 @@
// If this is the __VA_ARGS__ token, and if the argument wasn't provided,
// and if the macro had at least one real argument, and if the token before
- // the ## was a comma, remove the comma.
- if ((unsigned)ArgNo == Macro->getNumArgs()-1 && // is __VA_ARGS__
- ActualArgs->isVarargsElidedUse() && // Argument elided.
- !ResultToks.empty() && ResultToks.back().is(tok::comma)) {
- // Never add a space, even if the comma, ##, or arg had a space.
- NextTokGetsSpace = false;
- // Remove the paste operator, report use of the extension.
- PP.Diag(ResultToks.back().getLocation(), diag::ext_paste_comma);
- ResultToks.pop_back();
-
- // If the comma was right after another paste (e.g. "X##,##__VA_ARGS__"),
- // then removal of the comma should produce a placemarker token (in C99
- // terms) which we model by popping off the previous ##, giving us a plain
- // "X" when __VA_ARGS__ is empty.
- if (!ResultToks.empty() && ResultToks.back().is(tok::hashhash))
- ResultToks.pop_back();
- }
+ // the ## was a comma, remove the comma. This is a GCC extension which is
+ // disabled when using -std=c99.
+ if (ActualArgs->isVarargsElidedUse())
+ MaybeRemoveCommaBeforeVaArgs(ResultToks, NextTokGetsSpace,
+ /*HasPasteOperator=*/true,
+ Macro, ArgNo, PP);
+
continue;
}
Added: cfe/trunk/test/Preprocessor/macro_fn_comma_swallow2.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Preprocessor/macro_fn_comma_swallow2.c?rev=167613&view=auto
==============================================================================
--- cfe/trunk/test/Preprocessor/macro_fn_comma_swallow2.c (added)
+++ cfe/trunk/test/Preprocessor/macro_fn_comma_swallow2.c Fri Nov 9 07:24:30 2012
@@ -0,0 +1,64 @@
+// Test the __VA_ARGS__ comma swallowing extensions of various compiler dialects.
+
+// RUN: %clang_cc1 -E %s | FileCheck -check-prefix=GCC -strict-whitespace %s
+// RUN: %clang_cc1 -E -std=c99 %s | FileCheck -check-prefix=C99 -strict-whitespace %s
+// RUN: %clang_cc1 -E -std=c11 %s | FileCheck -check-prefix=C99 -strict-whitespace %s
+// RUN: %clang_cc1 -E -x c++ %s | FileCheck -check-prefix=GCC -strict-whitespace %s
+// RUN: %clang_cc1 -E -std=gnu99 %s | FileCheck -check-prefix=GCC -strict-whitespace %s
+// RUN: %clang_cc1 -E -fms-compatibility %s | FileCheck -check-prefix=MS -strict-whitespace %s
+// RUN: %clang_cc1 -E -DNAMED %s | FileCheck -check-prefix=GCC -strict-whitespace %s
+// RUN: %clang_cc1 -E -std=c99 -DNAMED %s | FileCheck -check-prefix=C99 -strict-whitespace %s
+
+
+#ifndef NAMED
+# define A(...) [ __VA_ARGS__ ]
+# define B(...) [ , __VA_ARGS__ ]
+# define C(...) [ , ## __VA_ARGS__ ]
+# define D(A,...) [ A , ## __VA_ARGS__ ]
+# define E(A,...) [ __VA_ARGS__ ## A ]
+#else
+// These are the GCC named argument versions of the C99-style variadic macros.
+// Note that __VA_ARGS__ *may* be used as the name, this is not prohibited!
+# define A(__VA_ARGS__...) [ __VA_ARGS__ ]
+# define B(__VA_ARGS__...) [ , __VA_ARGS__ ]
+# define C(__VA_ARGS__...) [ , ## __VA_ARGS__ ]
+# define D(A,__VA_ARGS__...) [ A , ## __VA_ARGS__ ]
+# define E(A,__VA_ARGS__...) [ __VA_ARGS__ ## A ]
+#endif
+
+
+1: A() B() C() D() E()
+2: A(a) B(a) C(a) D(a) E(a)
+3: A(,) B(,) C(,) D(,) E(,)
+4: A(a,b,c) B(a,b,c) C(a,b,c) D(a,b,c) E(a,b,c)
+5: A(a,b,) B(a,b,) C(a,b,) D(a,b,)
+
+// The GCC ", ## __VA_ARGS__" extension swallows the comma when followed by
+// empty __VA_ARGS__. This extension does not apply in -std=c99 mode, but
+// does apply in C++.
+//
+// GCC: 1: [ ] [ , ] [ ] [ ] [ ]
+// GCC: 2: [ a ] [ , a ] [ ,a ] [ a ] [ a ]
+// GCC: 3: [ , ] [ , , ] [ ,, ] [ , ] [ ]
+// GCC: 4: [ a,b,c ] [ , a,b,c ] [ ,a,b,c ] [ a ,b,c ] [ b,ca ]
+// GCC: 5: [ a,b, ] [ , a,b, ] [ ,a,b, ] [ a ,b, ]
+
+// Under C99 standard mode, the GCC ", ## __VA_ARGS__" extension *does not*
+// swallow the comma when followed by empty __VA_ARGS__.
+//
+// C99: 1: [ ] [ , ] [ , ] [ ] [ ]
+// C99: 2: [ a ] [ , a ] [ ,a ] [ a ] [ a ]
+// C99: 3: [ , ] [ , , ] [ ,, ] [ , ] [ ]
+// C99: 4: [ a,b,c ] [ , a,b,c ] [ ,a,b,c ] [ a ,b,c ] [ b,ca ]
+// C99: 5: [ a,b, ] [ , a,b, ] [ ,a,b, ] [ a ,b, ]
+
+// Microsoft's extension is on ", __VA_ARGS__" (without explicit ##) where
+// the comma is swallowed when followed by empty __VA_ARGS__.
+//
+// MS: 1: [ ] [ ] [ ] [ ] [ ]
+// MS: 2: [ a ] [ , a ] [ ,a ] [ a ] [ a ]
+// MS: 3: [ , ] [ , , ] [ ,, ] [ , ] [ ]
+// MS: 4: [ a,b,c ] [ , a,b,c ] [ ,a,b,c ] [ a ,b,c ] [ b,ca ]
+// MS: 5: [ a,b, ] [ , a,b, ] [ ,a,b, ] [ a ,b, ]
+
+// FIXME: Item 3(d) in MS output should be [ ] not [ , ]
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