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[Bug preprocessor/30363] New: Support for -traditional-cpp is incomplete in current gcc relative to gcc 2.95.3
- From: "fnf at specifixinc dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 4 Jan 2007 03:24:17 -0000
- Subject: [Bug preprocessor/30363] New: Support for -traditional-cpp is incomplete in current gcc relative to gcc 2.95.3
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
Given the following test case:
#define f(x, y) "x y"
extern void abort (void);
int main ()
{
const char *str1 = f("a", "\"a\"");
const char *str2 = f( \t, " \t");
if (strcmp (str1, "\"a\" \"\\\"a\\\"\""))
abort ();
if (strcmp (str2, "\t \" \\t\""))
abort ();
return 0;
}
Gcc 2.95.3 will accept it and do the right thing:
$ gcc -v
Reading specs from /opt/local/fsf/lib/gcc-lib/i686-pc-linux-gnu/2.95.3/specs
gcc version 2.95.3 20010315 (release)
$ gcc -traditional-cpp -o macroargs macroargs.c
$ ./macroargs
$
Current gcc 4.X fails to accept this code. For example, using the Fedora Core
6 compiler:
$ /usr/bin/gcc -v
Using built-in specs.
Target: i386-redhat-linux
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man
--infodir=/usr/share/info --enable-shared --enable-threads=posix
--enable-checking=release --with-system-zlib --enable-__cxa_atexit
--disable-libunwind-exceptions --enable-libgcj-multifile
--enable-languages=c,c++,objc,obj-c++,java,fortran,ada --enable-java-awt=gtk
--disable-dssi --enable-plugin
--with-java-home=/usr/lib/jvm/java-1.4.2-gcj-1.4.2.0/jre --with-cpu=generic
--host=i386-redhat-linux
Thread model: posix
gcc version 4.1.1 20061011 (Red Hat 4.1.1-30)
$ /usr/bin/gcc -traditional-cpp -o macroargs macroargs.c
macroargs.c: In function ?main?:
macroargs.c:7: error: expected ?,? or ?;? before ?a?
macroargs.c:7: error: stray ?\? in program
macroargs.c:7: error: missing terminating " character
macroargs.c:8: error: stray ?\? in program
macroargs.c:12: error: ?str2? undeclared (first use in this function)
macroargs.c:12: error: (Each undeclared identifier is reported only once
macroargs.c:12: error: for each function it appears in.)
The attached patch (also posted to gcc-patches) will fix it, although
it's handling of quoted arguments is not exactly identical to gcc
2.95.3. Notice the difference between the test case above, and the
test case included with the patch.
Here is an example of a patched gcc's behavior:
$ /opt/specifix/experimental/bin/gcc -v
Using built-in specs.
Target: i686-pc-linux-gnu
Configured with: /src/specifix/experimental/src/gcc/configure
--enable-languages=c,c++,fortran --prefix=/opt/specifix/experimental
--disable-werror --disable-bootstrap --with-mpfr=/opt/specifix/experimental
--with-gmp=/opt/specifix/experimental --cache-file=/dev/null
--srcdir=/src/specifix/experimental/src/gcc
Thread model: posix
gcc version 4.3.0 20061231 (experimental)
$ /opt/specifix/experimental/bin/gcc -traditional-cpp -o macroargs
macroargs.c
$
Note however that the above test case WILL abort if run, while the
test case included with the patch will not, due to the handling of
leading and trailing whitespace in macro args. See the code inside
"#if 0 ... #endif" in the patch and the associated comments. Either the
current gcc testsuite is wrong in how it tests for this whitespace, or
gcc 2.95.3 is wrong. It's not clear to me which behavior is more correct.
--
Summary: Support for -traditional-cpp is incomplete in current
gcc relative to gcc 2.95.3
Product: gcc
Version: 4.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: preprocessor
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: fnf at specifixinc dot com
GCC build triplet: i686-pc-linux-gnu
GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30363