[Bug c/78657] New: Using macro with _Pragma gives error: '#pragma' is not allowed here
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78657
Bug ID: 78657
Summary: Using macro with _Pragma gives error: '#pragma' is not
allowed here
Product: gcc
Version: 5.4.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: jquinsey at entrenet dot com
Target Milestone: ---
The following two-line source file test.c:
#define FOO _Pragma("GCC diagnostic push") 42
int foo = FOO;
gives:
gcc test.c -E
# 1 "test.c"
# 1 ""
# 1 ""
# 1 "test.c"
int foo =
# 2 "test.c"
#pragma GCC diagnostic push
# 2 "test.c"
42;
gcc test.c
test.c:2:1: error: expected expression before '#pragma'
int foo = FOO;
^
g++ -x c++ test.c
test.c:2:1: error: '#pragma' is not allowed here
int foo = FOO;
^
This appears to be consistent across many versions of gcc and g++. For example,
5.4.0 from Cygwin, 5.1 from this test sample at http://ideone.com/6unk5c, and
versions 4.4 through to 6.2 and 7 at https://godbolt.org/.
The icc and clang compilers (from 3.2 upwards) seem handle this correctly.
The text within the _Pragma doesn't seem relevant. Reversing the order of the
two parts of the macro gives a slightly different error message for C:
error: expected ',' or ';' before '#pragma'
[Bug c/78657] Using macro with _Pragma gives error: '#pragma' is not allowed here
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78657 --- Comment #2 from Joseph Quinsey --- The code int foo = #pragma GCC diagnostic push 42; gives exactly the same error messages. So this report is not about _Pragma per se, but about #pragma. But I cannot see where or if the standard addresses this. N1570 section 5.1.1.2, Translation phases, item 4 seems to say "All preprocessing directives are then deleted". Other preprocessor directives on the second line, such as int foo = #define BAR bar 42; are perfectly fine in gcc/g++ (including #include).
[Bug preprocessor/78657] Using macro with _Pragma gives error: '#pragma' is not allowed here
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78657 --- Comment #3 from Joseph Quinsey --- Similar or duplicate reports: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70811, https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63326, https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60875, https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59367, https://gcc.gnu.org/bugzilla/show_bug.cgi?id=50387.
[Bug preprocessor/78657] Using macro with _Pragma gives error: '#pragma' is not allowed here
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78657 Joseph Quinsey changed: What|Removed |Added See Also||https://gcc.gnu.org/bugzill ||a/show_bug.cgi?id=70811 --- Comment #4 from Joseph Quinsey --- Similar or duplicate reports: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70811, https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63326, https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60875, https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59367, https://gcc.gnu.org/bugzilla/show_bug.cgi?id=50387.
[Bug preprocessor/78657] Using macro with _Pragma gives error: '#pragma' is not allowed here
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78657 --- Comment #5 from Joseph Quinsey --- More similar or duplicate reports: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63612 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=43027 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=37267
[Bug c/45036] New: Copying array to static location with -O3 -march=native causes SEGV at runtime
Source:
int main(void) {
static int foo[4];
int bar[4];
int i;
for (i = 0; i < 4; i++)
foo[i] = bar[i];
return 0;
}
Compile and run:
gcc -O3 -march=native foobar.c
a.exe
Segmentation fault (core dumped)
The loop is compiled as:
movdqu -20(%ebp), %xmm0
xorl%eax, %eax
movaps %xmm0, _foo.1548
Version: gcc -v
Using built-in specs.
Target: i686-pc-cygwin
Configured with:
/gnu/gcc/releases/packaging/4.3.4-3/gcc4-4.3.4-3/src/gcc-4.3.4/configure
--srcdir=/gnu/gcc/releases/packaging/4.3.4-3/gcc4-4.3.4-3/src/gcc-4.3.4
--prefix=/usr --exec-prefix=/usr --bindir=/usr/bin --sbindir=/usr/sbin
--libexecdir=/usr/lib --datadir=/usr/share --localstatedir=/var
--sysconfdir=/etc --infodir=/usr/share/info --mandir=/usr/share/man
--datadir=/usr/share --infodir=/usr/share/info --mandir=/usr/share/man -v
--with-gmp=/usr --with-mpfr=/usr --enable-bootstrap
--enable-version-specific-runtime-libs --with-slibdir=/usr/bin
--libexecdir=/usr/lib --enable-static --enable-shared --enable-shared-libgcc
--disable-__cxa_atexit --with-gnu-ld --with-gnu-as --with-dwarf2
--disable-sjlj-exceptions
--enable-languages=ada,c,c++,fortran,java,objc,obj-c++ --disable-symvers
--enable-libjava --program-suffix=-4 --enable-libgomp --enable-libssp
--enable-libada --enable-threads=posix --with-arch=i686 --with-tune=generic
--enable-libgcj-sublibs CC=gcc-4 CXX=g++-4 CC_FOR_TARGET=gcc-4
CXX_FOR_TARGET=g++-4 GNATMAKE_FOR_TARGET=gnatmake GNATBIND_FOR_TARGET=gnatbind
AS=/opt/gcc-tools/bin/as.exe AS_FOR_TARGET=/opt/gcc-tools/bin/as.exe
LD=/opt/gcc-tools/bin/ld.exe LD_FOR_TARGET=/opt/gcc-tools/bin/ld.exe
--with-ecj-jar=/usr/share/java/ecj.jar
Thread model: posix
gcc version 4.3.4 20090804 (release) 1 (GCC)
--
Summary: Copying array to static location with -O3 -march=native
causes SEGV at runtime
Product: gcc
Version: 4.3.4
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: jquinsey at entrenet dot com
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45036
[Bug c/49915] New: Function call with 2-D arrays and -O2 (or strict-aliasing and inlining) gives random results
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49915
Summary: Function call with 2-D arrays and -O2 (or
strict-aliasing and inlining) gives random results
Product: gcc
Version: 4.1.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: jquin...@entrenet.com
Created attachment 24872
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=24872
test.i from gcc -v -save-temps -O2 test.c
A function call with two-dimensional arrays and -O2 (or the switches
-fstrict-aliasing and -finline) gives random results.
Complete source code (14 lines):
static void copy(int n, int a[][n], int b[][n]) {
int i, j;
for (i = 0; i < 2; i++)// 'n' not used in this example
for (j = 0; j < 2; j++) // 'n' hard-coded to 2 for simplicity
b[i][j] = a[i][j];
}
int main(int argc, char *argv[]) {
int a[2][2] = {{1, 2},{3, 4}};
int b[2][2];
copy(2, a, b);
printf("%d %d %d %d\n", b[0][0], b[0][1], b[1][0], b[1][1]);
return 0;
}
Test results:
gcc -O1 test.c && a.out
1 2 3 4
gcc -O2 test.c && a.out
12173125 -1079787588 -1079787736 13389812
gcc -O1 -fstrict-aliasing -finline test.c && a.out
12173125 -1080040260 -1080040408 13389812
All three tests also produced the (obvious) warning:
test.c: In function 'main':
test.c:12: warning: incompatible implicit declaration of built-in function
'printf'
gcc -v -save-temps -O2 test.c
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 --disable-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 4.1.2 20080704 (Red Hat 4.1.2-50)
/usr/libexec/gcc/i386-redhat-linux/4.1.2/cc1 -E -quiet -v test.c
-mtune=generic -O2 -fpch-preprocess -o test.i
ignoring nonexistent directory
"/usr/lib/gcc/i386-redhat-linux/4.1.2/../../../../i386-redhat-linux/include"
#include "..." search starts here:
#include <...> search starts here:
/usr/local/include
/usr/lib/gcc/i386-redhat-linux/4.1.2/include
/usr/include
End of search list.
/usr/libexec/gcc/i386-redhat-linux/4.1.2/cc1 -fpreprocessed test.i -quiet
-dumpbase test.c -mtune=generic -auxbase test -O2 -version -o test.s
GNU C version 4.1.2 20080704 (Red Hat 4.1.2-50) (i386-redhat-linux)
compiled by GNU C version 4.1.2 20080704 (Red Hat 4.1.2-50).
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: d8d95095eb3c93dae4bed2137d559f95
test.c: In function 'main':
test.c:12: warning: incompatible implicit declaration of built-in function
'printf'
as -V -Qy -o test.o test.s
GNU assembler version 2.17.50.0.6-14.el5 (i386-redhat-linux) using BFD version
2.17.50.0.6-14.el5 20061020
/usr/libexec/gcc/i386-redhat-linux/4.1.2/collect2 --eh-frame-hdr -m elf_i386
--hash-style=gnu -dynamic-linker /lib/ld-linux.so.2
/usr/lib/gcc/i386-redhat-linux/4.1.2/../../../crt1.o
/usr/lib/gcc/i386-redhat-linux/4.1.2/../../../crti.o
/usr/lib/gcc/i386-redhat-linux/4.1.2/crtbegin.o
-L/usr/lib/gcc/i386-redhat-linux/4.1.2 -L/usr/lib/gcc/i386-redhat-linux/4.1.2
-L/usr/lib/gcc/i386-redhat-linux/4.1.2/../../.. test.o -lgcc --as-needed
-lgcc_s --no-as-needed -lc -lgcc --as-needed -lgcc_s --no-as-needed
/usr/lib/gcc/i386-redhat-linux/4.1.2/crtend.o
/usr/lib/gcc/i386-redhat-linux/4.1.2/../../../crtn.o
