When compiling ltrace with icecc we run into a compilation problem. This is the minimal example:
main.c
#include <assert.h>
int main(int argc, char **argv) {
assert(argc != argc);
return 0;
}
test.sh:
#!/bin/bash
set -x
# one step compilation (no warning)
gcc -Wall main.c
# splitted compilation (warning)
gcc -Wall -E main.c -o main.i
gcc -Wall --preprocessed main.i
output:
++ gcc -Wall main.c
++ gcc -Wall -E main.c -o main.i
++ gcc -Wall --preprocessed main.i
main.c: In function ‘main’:
main.c:4:10: warning: self-comparison always evaluates to false [-Wtautological-compare]
assert(argc != argc);
^~
As you can see the result is different when compiling in one step and when preprocessing and compiling in two steps. Is this intended behavior?
I use gcc 6.3, the issue also appears in gcc 6.2 for ARM. I also cannot ignore this, as the full example uses -Werror.
Related
When using a lambda expression my compiler shows me an error. This is the implementation (where name is a std::string&):
auto expression = [name](const Item* x) -> bool { return x->get_name() == name; };
This is the error:
items/container.cpp:20:27: error: expected expression
auto expression = [name](const Item* x) -> bool { return x->get_name() == name; };
These are my compiler flags:
CFLAGS=$(-std=c++11 -stdlib=libc++ -g -Wall -Werror -Wextra -I.)
All other C++11 features I have used have worked so far. I am using MacOS 10.11.3.
>> clang --version
Apple LLVM version 7.0.2 (clang-700.1.81)
Target: x86_64-apple-darwin15.3.0
Thread model: posix
>> clang++ --version
Apple LLVM version 7.0.2 (clang-700.1.81)
Target: x86_64-apple-darwin15.3.0
Thread model: posix
Unfortunately this did not help me: Clang 3.1 and C++11 support status
UPDATE: After creating a minimal example as suggested by the comments below it worked! The problem must lie in my makefile. This reproduces the error:
CC=clang++
CFLAGS=$(-stdlib=libc++ -std=c++11 -g -Wall -Werror -Wextra -I.)
all: main
main: main.o
$(CC) $(CFLAGS) -o main *.o
main.o: main.cpp
$(CC) $(CFLAGS) -c main.cpp
My main.cpp file:
#include <iostream>
#include <string>
int main() {
auto lambda = [](const std::string& str) { return str == "whatever"; };
std::string s1 = "something else";
std::string s2 = "whatever";
std::cout << "should be false: " << lambda(s1) << std::endl;
std::cout << "should be true: " << lambda(s2) << std::endl;
return 0;
}
You're misusing the $ sign in your makefile. It's for substitutions of variables so $(-stdlib=libc++ ...) would suggest you had a variable whose name started with -stdlib=... (I'm surprised this isn't giving you an error)
If you don't want a substitution and just want literal content, write it after the = sign unescaped:
CC=clang++
CFLAGS=-stdlib=libc++ -std=c++11 -g -Wall -Werror -Wextra -I.
all: main
main: main.o
$(CC) $(CFLAGS) -o main *.o
main.o: main.cpp
$(CC) $(CFLAGS) -c main.cpp
I'm trying to setup Mingw-w64 as the mex compiler in MATLAB 2013a. My laptop has x86_64 architecture and runs windows 7. The program I want to compile uses c++11-style threading, so I'm using mingw-w64 version 4.9.0 with posix threads.
According to instruction I found here and here, I modified my mexopts.bat file. The code seems to compile successfully, but the linker reports an error. Does anyone have suggestions what I might be doing wrong?
By the way, I tried using gnumex to setup the compiler, but that didn't work either.
Here's the output and error message that MATLAB gives:
>mex -v Gomoku_mex.cpp
-> Default options filename found in C:\Users\Bas\AppData\Roaming\MathWorks\MATLAB\R2013a
-> Options file = C:\Users\Bas\AppData\Roaming\MathWorks\MATLAB\R2013a\mexopts.bat
MATLAB = C:\Program Files\MATLAB\R2013a
-> COMPILER = x86_64-w64-mingw32-g++
-> Compiler flags:
COMPFLAGS = -std=c++11 -fexceptions -I"C:\Program Files\MATLAB\R2013a\extern\include"
OPTIMFLAGS = -O3 -fexpensive-optimizations -DNDEBUG
DEBUGFLAGS = -g -Wall -Wextra
arguments =
Name switch = -o
-> Pre-linking commands=
-> LINKER = x86_64-w64-mingw32-g++
-> Link directives:
LINKFLAGS = -shared mex.def -L"C:\Program Files\MATLAB\R2013a\bin\win64" -static-libstdc++
LINKDEBUGFLAGS = -g -Wall
LINKFLAGSPOST = -lmex -lmx -lmat -lmwlapack -lmwblas
Name directive = -o "Gomoku_mex.mexw64"
File link directive =
Lib. link directive =
Rsp file indicator =
-> Resource Compiler =
-> Resource Linker =
----------------------------------------------------------------
--> x86_64-w64-mingw32-g++ -std=c++11 -fexceptions -I"C:\Program Files\MATLAB\R2013a\extern\include" -oC:\Users\Bas\AppData\Local\Temp\mex_r7jRw0\Gomoku_mex.obj -I"C:\Program Files\MATLAB\R2013a\extern\include" -I"C:\Program Files\MATLAB\R2013a\simulink\include" -O3 -fexpensive-optimizations -DNDEBUG -DMX_COMPAT_32 Gomoku_mex.cpp
C:\Users\Bas\AppData\Local\Temp\cc4hwD3A.o:Gomoku_mex.cpp:(.text+0x9d1c): undefined reference to `mxGetPr'
C:\Users\Bas\AppData\Local\Temp\cc4hwD3A.o:Gomoku_mex.cpp:(.text+0x9d83): undefined reference to `mxCreateDoubleScalar'
C:/PROGRA~1/mingw-w64/x86_64-4.9.0-posix-seh-rt_v3-rev2/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/4.9.0/../../../../x86_64-w64-mingw32/bin/ld.exe: C:\Users\Bas\AppData\Local\Temp\cc4hwD3A.o: bad reloc address 0x0 in section `.pdata$_ZNKSt5ctypeIcE8do_widenEc'
collect2.exe: error: ld returned 1 exit status
C:\PROGRA~1\MATLAB\R2013A\BIN\MEX.PL: Error: Compile of 'Gomoku_mex.cpp' failed.
Error using mex (line 206)
Unable to complete successfully.
Edit: As extra information, this is my mexopts.bat file. I got this directly from one of the two links above and modified directory & compiler names and added -std=c++11
set MATLAB=%MATLAB%
set PATH=%PATH%;C:\PROGRA~1\mingw-w64\x86_64-4.9.0-posix-seh-rt_v3-rev2\mingw64\bin
set MW_TARGET_ARCH=win64
rem ********************************************************************
rem Compiler parameters
rem ********************************************************************
set COMPILER=x86_64-w64-mingw32-g++
set COMPFLAGS=-std=c++11 -fexceptions -I"%MATLAB%\extern\include"
set OPTIMFLAGS=-O3 -fexpensive-optimizations -DNDEBUG
set DEBUGFLAGS=-g -Wall -Wextra
set NAME_OBJECT=-o
rem ********************************************************************
rem Linker parameters
rem ********************************************************************
set PRELINK_CMDS1=echo EXPORTS > mex.def & echo mexFunction >> mex.def
set LINKER=x86_64-w64-mingw32-g++
set LINKFLAGS= -static-libstdc++ -shared mex.def -L"%MATLAB%\bin\win64" -L"%MATLAB%\extern\lib\win64\microsoft"
set LINKFLAGSPOST= -lmex -lmx -lmat -lmwlapack -lmwblas
set LINKOPTIMFLAGS=-O3
set LINKDEBUGFLAGS= -g -Wall
set LINK_FILE=
set LINK_LIB=
set NAME_OUTPUT=-o "%OUTDIR%%MEX_NAME%%MEX_EXT%"
set RSP_FILE_INDICATOR=
set POSTLINK_CMDS1=del mex.def
Take the following configuration file that I'm using (you'll need to adjust the path pointing to MinGW-w64 location accordingly):
mingw_mexopts.bat
#echo off
set MATLAB=%MATLAB%
set MW_TARGET_ARCH=win64
set PATH=C:\MinGW-w64\mingw64\bin;%PATH%
set COMPILER=x86_64-w64-mingw32-g++
set COMPFLAGS=-c -m64 -mwin32 -mdll -Wall -std=c++11 -DMATLAB_MEX_FILE
set OPTIMFLAGS=-DNDEBUG -O2
set DEBUGFLAGS=-g
set NAME_OBJECT=-o
set LINKER=x86_64-w64-mingw32-g++
set LINKFLAGS=-shared -L"%MATLAB%\extern\lib\win64\microsoft" -L"%MATLAB%\bin\win64"
set LINKFLAGSPOST=-lmx -lmex -lmat
set LINKOPTIMFLAGS=-O2
set LINKDEBUGFLAGS=-g
set LINK_FILE=
set LINK_LIB=
set NAME_OUTPUT=-o "%OUTDIR%%MEX_NAME%%MEX_EXT%"
Next here is a simple MEX-function that uses C++11 threads:
test.cpp
#include "mex.h"
#include <vector>
#include <thread>
void say_hello(int tid) {
mexPrintf("hello from %d\n", tid);
}
void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[])
{
std::vector<std::thread> threads;
for (int i=0; i<10; i++) {
threads.push_back(std::thread(say_hello, i));
}
for(auto& t : threads) {
t.join();
}
}
Finally we compile and run it in MATLAB:
>> mex -f mingw_mexopts.bat -largeArrayDims test.cpp
>> setenv('PATH', ['C:\MinGW-w64\mingw64\bin;', getenv('PATH')])
>> test
hello from 0
hello from 4
hello from 2
hello from 3
hello from 5
hello from 1
hello from 6
hello from 8
hello from 7
hello from 9
Note that if you're going to deploy this to another machine, you'll have to also copy a few dependent DLL's (you'll find them in MinGW bin folder), and place them next to the MEX-file. Use Dependency Walker to list them. In my case it was:
libstdc++-6.dll
libgcc_s_seh-1.dll
libwinpthread-1.dll
I am using GCC 4.8.2 with MATLAB R2014a running on 64-bit Windows.
Note these error messages:
C:\Users\Bas\AppData\Local\Temp\cc4hwD3A.o:Gomoku_mex.cpp:(.text+0x9d1c): undefined reference to `mxGetPr'
C:\Users\Bas\AppData\Local\Temp\cc4hwD3A.o:Gomoku_mex.cpp:(.text+0x9d83): undefined reference to `mxCreateDoubleScalar'
The library search path for libmex, libmx, libmat, ... is not added in your link command. The directory in your script is the bin directory containing DLLs. That's not correct here.
LINKFLAGS = -shared mex.def -L"C:\Program Files\MATLAB\R2013a\extern\lib\win64\microsoft" -static-libstdc++
I am running following command:
gcc -DPJ_AUTOCONF=1 -fPIC -DPJ_IS_BIG_ENDIAN=0 -DPJ_IS_LITTLE_ENDIAN=1 -I/usr/local/include -L/usr/local/lib -lpjsua-x86_64-unknown-linux-gnu -lpjsip-ua-x86_64-unknown-linux-gnu -lpjsip-simple-x86_64-unknown-linux-gnu -lpjsip-x86_64-unknown-linux-gnu -lpjmedia-codec-x86_64-unknown-linux-gnu -lpjmedia-videodev-x86_64-unknown-linux-gnu -lpjmedia-x86_64-unknown-linux-gnu -lpjmedia-audiodev-x86_64-unknown-linux-gnu -lpjnath-x86_64-unknown-linux-gnu -lpjlib-util-x86_64-unknown-linux-gnu -lresample-x86_64-unknown-linux-gnu -lmilenage-x86_64-unknown-linux-gnu -lsrtp-x86_64-unknown-linux-gnu -lgsmcodec-x86_64-unknown-linux-gnu -lspeex-x86_64-unknown-linux-gnu -lilbccodec-x86_64-unknown-linux-gnu -lg7221codec-x86_64-unknown-linux-gnu -lportaudio-x86_64-unknown-linux-gnu -lpj-x86_64-unknown-linux-gnu -lm -lnsl -lrt -lpthread -lcrypto -lssl pjsuaCreate.c
The content of pjsuaCreate.c is:
#include <pjsua-lib/pjsua.h>
int main(int argc, char *argv[])
{
pj_status_t status = pjsua_create();
return 0;
}
I am getting:
/tmp/cc7U0i1Q.o: In function `main': pjsuaCreate.c:(.text+0x10): undefined reference to `pjsua_create'
collect2: ld returned 1 exit status
Im on Ubuntu and doing grep shows following:
$ grep -r "pjsua_create" /usr/local/lib/
Binary file /usr/local/lib/python2.7/dist-packages/_pjsua.so matches
Binary file /usr/local/lib/libpjsua-x86_64-unknown-linux-gnu.a matches
Since at least some of the libraries are static (archives), you might be encountering the dependency ordering problem described here.
Enclose the -l<lib1> -l<lib2> ... options between the -Wl,--start-group and -Wl,--end-group options (linker flags) respectively.
Im using gcc on Linux and creating a shared library for static libraries. I dont want symbols from some static libraries to be exported.
gcc version is 4.8.0.
Im trying this option at gcc command and it's not working:
-Wl,--exclude-libs,libabc.a .
If I use this option, it's removing all the symbols which not what I want.:
-Wl,--exclude-libs,ALL
Can somebody help in how to use --exclude-option and not to export symbols from specific static library, please?
Thanks
Chandra
Please ignore my comment to question, it is incorrect.
Minimal example:
test1.c:
int testvar1;
int test1(void) {
return 1;
}
test2.c:
extern int testvar1;
int test1(void);
int test2(void) {
testvar1 = -1;
return test1() + 2;
}
test.c:
#include <stdio.h>
#include <dlfcn.h>
int main(int argc, char **argv) {
void *lib = dlopen("./libtest2.so", RTLD_NOW);
int (*f)(void) = dlsym(lib, "test2");
printf("%d\n", f());
return 0;
}
Build:
$ gcc -fPIC -c test1.c
$ ar cru libtest1.a test1.o
$ gcc -fPIC -c test2.c
$ gcc -shared -o libtest2.so test2.o -L. -ltest1 -Wl,--exclude-libs,libtest1.a
$ gcc test.c -ldl
$ ./a.out
3
$ readelf --syms -D libtest2.so | grep test1
$
I'm playing around with XPC, GCD and go but I hit a quick wall when my code was failing to compile with the following error messages (which I don't understand):
main(__DATA/__const): unexpected reloc for dynamic symbol _NSConcreteGlobalBlock
main(__DATA/__const): unhandled relocation for _NSConcreteGlobalBlock (type 28 rtype 120)
I am compiling using go build the code that follows:
main.go
package main
/*
#include <xpc/xpc.h>
#include "wrapper.h"
*/
import "C"
import (
"fmt"
)
//export HandleXPCEvent
func HandleXPCEvent(event C.xpc_object_t) {
fmt.Println("Event was handled")
}
func main() {
name := C.CString("com.example.xpc")
queue := C.dispatch_queue_create(name, nil)
conn := C.xpc_connection_create(name, queue)
C.set_event_handler(conn)
//C.xpc_connection_resume(conn)
}
wrapper.h
#ifndef _WRAPPER_H_
#define _WRAPPER_H_
#include <stdlib.h>
#include <stdio.h>
#include <xpc/xpc.h>
xpc_connection_t connect( char* name);
void set_event_handler(xpc_connection_t connection);
#endif
wrapper.c
#include "wrapper.h"
#include <dispatch/dispatch.h>
extern void HandleXPCEvent(xpc_object_t);
xpc_connection_t connect( char* name) {
dispatch_queue_t queue = dispatch_queue_create(name,0);
return xpc_connection_create(name,queue);
}
void set_event_handler(xpc_connection_t connection) {
xpc_connection_set_event_handler(connection, ^(xpc_object_t event) {
xpc_retain(event);
// Call Go function
HandleXPCEvent(event);
});
}
I'm I doing something wrong? Is this some kind of go bug or how can this be fixed?
Update:
I ran go build -x -work on my project and I got the following output:
➣ go build -x -work
WORK=/var/folders/fb/bgfqk8wx5x16w7yh2cg50vrw0000gn/T/go-build524335717
mkdir -p $WORK/github.com/gabrielayuso/go-xpc/_obj/
mkdir -p $WORK/github.com/gabrielayuso/go-xpc/_obj/exe/
cd /Users/gabrielayuso/Documents/Workspace/Projects/go/src/github.com/gabrielayuso/go-xpc
/usr/local/go/pkg/tool/darwin_amd64/cgo -objdir $WORK/github.com/gabrielayuso/go-xpc/_obj/ -- -I $WORK/github.com/gabrielayuso/go-xpc/_obj/ main.go
/usr/local/go/pkg/tool/darwin_amd64/6c -F -V -w -I $WORK/github.com/gabrielayuso/go-xpc/_obj/ -I /usr/local/go/pkg/darwin_amd64 -o $WORK/github.com/gabrielayuso/go-xpc/_obj/_cgo_defun.6 -D GOOS_darwin -D GOARCH_amd64 $WORK/github.com/gabrielayuso/go-xpc/_obj/_cgo_defun.c
gcc -I . -g -O2 -fPIC -m64 -pthread -fno-common -print-libgcc-file-name
gcc -I . -g -O2 -fPIC -m64 -pthread -fno-common -I $WORK/github.com/gabrielayuso/go-xpc/_obj/ -o $WORK/github.com/gabrielayuso/go-xpc/_obj/_cgo_main.o -c $WORK/github.com/gabrielayuso/go-xpc/_obj/_cgo_main.c
gcc -I . -g -O2 -fPIC -m64 -pthread -fno-common -I $WORK/github.com/gabrielayuso/go-xpc/_obj/ -o $WORK/github.com/gabrielayuso/go-xpc/_obj/_cgo_export.o -c $WORK/github.com/gabrielayuso/go-xpc/_obj/_cgo_export.c
gcc -I . -g -O2 -fPIC -m64 -pthread -fno-common -I $WORK/github.com/gabrielayuso/go-xpc/_obj/ -o $WORK/github.com/gabrielayuso/go-xpc/_obj/main.cgo2.o -c $WORK/github.com/gabrielayuso/go-xpc/_obj/main.cgo2.c
gcc -I . -g -O2 -fPIC -m64 -pthread -fno-common -I $WORK/github.com/gabrielayuso/go-xpc/_obj/ -o $WORK/github.com/gabrielayuso/go-xpc/_obj/wrapper.o -c ./wrapper.c
gcc -I . -g -O2 -fPIC -m64 -pthread -fno-common -o $WORK/github.com/gabrielayuso/go-xpc/_obj/_cgo_.o $WORK/github.com/gabrielayuso/go-xpc/_obj/_cgo_main.o $WORK/github.com/gabrielayuso/go-xpc/_obj/_cgo_export.o $WORK/github.com/gabrielayuso/go-xpc/_obj/main.cgo2.o $WORK/github.com/gabrielayuso/go-xpc/_obj/wrapper.o
/usr/local/go/pkg/tool/darwin_amd64/cgo -objdir $WORK/github.com/gabrielayuso/go-xpc/_obj/ -dynimport $WORK/github.com/gabrielayuso/go-xpc/_obj/_cgo_.o -dynout $WORK/github.com/gabrielayuso/go-xpc/_obj/_cgo_import.c
/usr/local/go/pkg/tool/darwin_amd64/6c -F -V -w -I $WORK/github.com/gabrielayuso/go-xpc/_obj/ -I /usr/local/go/pkg/darwin_amd64 -o $WORK/github.com/gabrielayuso/go-xpc/_obj/_cgo_import.6 -D GOOS_darwin -D GOARCH_amd64 $WORK/github.com/gabrielayuso/go-xpc/_obj/_cgo_import.c
gcc -I . -g -O2 -fPIC -m64 -pthread -fno-common -o $WORK/github.com/gabrielayuso/go-xpc/_obj/_all.o $WORK/github.com/gabrielayuso/go-xpc/_obj/_cgo_export.o $WORK/github.com/gabrielayuso/go-xpc/_obj/main.cgo2.o $WORK/github.com/gabrielayuso/go-xpc/_obj/wrapper.o -Wl,-r -nostdlib /usr/llvm-gcc-4.2/bin/../lib/gcc/i686-apple-darwin11/4.2.1/x86_64/libgcc.a
/usr/local/go/pkg/tool/darwin_amd64/6g -o $WORK/github.com/gabrielayuso/go-xpc/_obj/_go_.6 -p github.com/gabrielayuso/go-xpc -D _/Users/gabrielayuso/Documents/Workspace/Projects/go/src/github.com/gabrielayuso/go-xpc -I $WORK $WORK/github.com/gabrielayuso/go-xpc/_obj/_cgo_gotypes.go $WORK/github.com/gabrielayuso/go-xpc/_obj/main.cgo1.go
/usr/local/go/pkg/tool/darwin_amd64/pack grcP $WORK $WORK/github.com/gabrielayuso/go-xpc.a $WORK/github.com/gabrielayuso/go-xpc/_obj/_go_.6 $WORK/github.com/gabrielayuso/go-xpc/_obj/_cgo_import.6 $WORK/github.com/gabrielayuso/go-xpc/_obj/_cgo_defun.6 $WORK/github.com/gabrielayuso/go-xpc/_obj/_all.o
cd .
/usr/local/go/pkg/tool/darwin_amd64/6l -o $WORK/github.com/gabrielayuso/go-xpc/_obj/exe/a.out -L $WORK $WORK/github.com/gabrielayuso/go-xpc.a
# github.com/gabrielayuso/go-xpc
main(__DATA/__const): unexpected reloc for dynamic symbol _NSConcreteGlobalBlock
main(__DATA/__const): unhandled relocation for _NSConcreteGlobalBlock (type 28 rtype 120)
Content of $WORK dir as generated by go build -x -work: go-xpc_work.zip
I'm not very familiar with compiling and linking therefore I can't make much sense of this output. I just noticed that _cgo_import.c a file generated by cgo (with options -dynimport and -dynout) has #pragma cgo_import_dynamic _NSConcreteGlobalBlock _NSConcreteGlobalBlock "" in the first line which is related to the error message the linker gave.
Hope this information can help to find out what the problem is and how to solve it.
I don't know much about those libraries but nothing jumps out at me with the code you have here.
Some useful debug output can be obtained from go build -x -work which will print the commands and the working directory for you.
The working directory will be left untouched so you can go look at the code cgo generates for you. That plus the commands it will print for you should get you started on tracking down the problem.
I have a wrapper written up for using Go and XPC in Cocoa Applications.
It's located here:
https://github.com/aventurella/go-xpc