http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60304
Bug ID: 60304
Summary: Including <atomic> disables -Wconversion-null
Product: gcc
Version: 4.8.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: preprocessor
Assignee: unassigned at gcc dot gnu.org
Reporter: bug-reports at psdtechnologies dot com
Created attachment 32190
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=32190&action=edit
Minimal example of bug (does not emit warning)
Compiling any code with '#include <atomic>' disables the conversion-null
warning, but only when compiling directly from source; preprocessing separately
does not reproduce the bug.
I've attached minimal examples, reproduced here since they're so short (1-2
lines)
This file behaves as expected (warning.cpp):
"""
int * foo() {return false;}
"""
$ g++-4.8 -std=c++11 -c warning.cpp
warning.cpp: In function ‘int* foo()’:
warning.cpp:1:21: warning: converting ‘false’ to pointer type ‘int*’
[-Wconversion-null]
int * foo() {return false;}
^
This warning is expected since -Wconversion-null is enabled by default. It also
can be made to error as expected using -Wall or by inserting
"""
#pragma GCC diagnostic error "-Wconversion-null"
"""
in the source prior to the function.
This file (differing only by the inclusion of <atomic> does not issue the
warning, and cannot be made to error or warn even with the pragma:
"""
#include <atomic>
int * foo() {return false;}
"""
g++-4.8 -std=c++11 -c nowarning.cpp # success
Compiling incrementally, though, restores the expected behavior:
g++-4.8 -std=c++11 -E nowarning.cpp -o nowarning.i # success
g++-4.8 -std=c++11 -c nowarning.i
nowarning.cpp: In function ‘int* foo()’:
nowarning.cpp:2:21: warning: converting ‘false’ to pointer type ‘int*’
[-Wconversion-null]
int * foo() {return false;}
^
As does using -save-temps:
g++-4.8 -std=c++11 -save-temps -c nowarning.cpp
nowarning.cpp: In function ‘int* foo()’:
nowarning.cpp:2:21: warning: converting ‘false’ to pointer type ‘int*’
[-Wconversion-null]
int * foo() {return false;}
^
Version information:
g++-4.8 -std=c++11 -v -c nowarning.cpp
Using built-in specs.
COLLECT_GCC=g++-4.8
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu
4.8.1-2ubuntu1~12.04' --with-bugurl=file:///usr/share/doc/gcc-4.8/README.Bugs
--enable-languages=c,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr
--program-suffix=-4.8 --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--with-gxx-include-dir=/usr/include/c++/4.8 --libdir=/usr/lib --enable-nls
--with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug
--enable-libstdcxx-time=yes --enable-gnu-unique-object --enable-plugin
--with-system-zlib --disable-browser-plugin --enable-java-awt=gtk
--enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-4.8-amd64/jre
--enable-java-home --with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-4.8-amd64
--with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-4.8-amd64
--with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar
--enable-objc-gc --enable-multiarch --disable-werror --with-arch-32=i686
--with-abi=m64 --with-multilib-list=m32,m64 --with-tune=generic
--enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu
--target=x86_64-linux-gnu
Thread model: posix
gcc version 4.8.1 (Ubuntu 4.8.1-2ubuntu1~12.04)
COLLECT_GCC_OPTIONS='-std=c++11' '-v' '-c' '-shared-libgcc' '-mtune=generic'
'-march=x86-64'
/usr/lib/gcc/x86_64-linux-gnu/4.8/cc1plus -quiet -v -imultilib . -imultiarch
x86_64-linux-gnu -D_GNU_SOURCE nowarning.cpp -quiet -dumpbase nowarning.cpp
-mtune=generic -march=x86-64 -auxbase nowarning -std=c++11 -version
-fstack-protector -o /tmp/ccCyoaqJ.s
GNU C++ (Ubuntu 4.8.1-2ubuntu1~12.04) version 4.8.1 (x86_64-linux-gnu)
compiled by GNU C version 4.8.1, GMP version 5.0.2, MPFR version 3.1.0-p3,
MPC version 0.9
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
ignoring duplicate directory "/usr/include/x86_64-linux-gnu/c++/4.8"
ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu"
ignoring nonexistent directory
"/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../../x86_64-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
/usr/include/c++/4.8
/usr/include/x86_64-linux-gnu/c++/4.8/.
/usr/include/c++/4.8/backward
/usr/lib/gcc/x86_64-linux-gnu/4.8/include
/usr/local/include
/usr/lib/gcc/x86_64-linux-gnu/4.8/include-fixed
/usr/include/x86_64-linux-gnu
/usr/include
End of search list.
GNU C++ (Ubuntu 4.8.1-2ubuntu1~12.04) version 4.8.1 (x86_64-linux-gnu)
compiled by GNU C version 4.8.1, GMP version 5.0.2, MPFR version 3.1.0-p3,
MPC version 0.9
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 227d7ccf008db5ae401be7ddcc6b4746
COLLECT_GCC_OPTIONS='-std=c++11' '-v' '-c' '-shared-libgcc' '-mtune=generic'
'-march=x86-64'
as -v --64 -o nowarning.o /tmp/ccCyoaqJ.s
GNU assembler version 2.22 (x86_64-linux-gnu) using BFD version (GNU Binutils
for Ubuntu) 2.22
COMPILER_PATH=/usr/lib/gcc/x86_64-linux-gnu/4.8/:/usr/lib/gcc/x86_64-linux-gnu/4.8/:/usr/lib/gcc/x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/4.8/:/usr/lib/gcc/x86_64-linux-gnu/
LIBRARY_PATH=/usr/lib/gcc/x86_64-linux-gnu/4.8/:/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../../lib/:/lib/x86_64-linux-gnu/:/lib/../lib/:/usr/lib/x86_64-linux-gnu/:/usr/lib/../lib/:/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-std=c++11' '-v' '-c' '-shared-libgcc' '-mtune=generic'
'-march=x86-64'
