Hi I get the following warnings
g++ -std=c++0x -Wall -c -I/usr/local/boost_1_53_0 -I/home/aditya/CodeBase/includes MAIN.cpp
In file included from /usr/local/boost_1_53_0/boost/interprocess/detail/managed_open_or_create_impl.hpp:15:0,
from /usr/local/boost_1_53_0/boost/interprocess /managed_shared_memory.hpp:22,
from MAIN.cpp:22:
/usr/local/boost_1_53_0/boost/interprocess/detail/os_thread_functions.hpp: In function ‘void boost::interprocess::ipcdetail::thread_sleep(unsigned int)’:
/usr/local/boost_1_53_0/boost/interprocess/detail/os_thread_functions.hpp:169:65: warning: narrowing conversion of ‘(ms / 1000u)’ from ‘unsigned int’ to ‘__time_t {aka long int}’ inside { } [-Wnarrowing]
/usr/local/boost_1_53_0/boost/interprocess/detail/os_thread_functions.hpp:169:65: warning: narrowing conversion of ‘((ms % 1000u) * 1000000u)’ from ‘unsigned int’ to ‘long int’ inside { } [-Wnarrowing]
on compiling the following program
#include <iostream>
#include <memory>
#include <boost/thread.hpp>
#include <boost/managed_shared_memory.hpp>
int main(){
return 0;
}
I'm using gcc 4.7 on an ubuntu 12.04
Related
I am not sure if I am the only person or this is the problem of so many other people.
What I suffer from is that for an even simple code that includes LLVM headers regardless of what ever I write in my main function, I get too many warnings when I compile my codes with extra warnings:
#include <llvm/IR/IRBuilder.h>
#include <llvm/IR/Verifier.h>
#include <llvm/Support/TargetSelect.h>
#include <llvm/ExecutionEngine/ExecutionEngine.h>
#include <llvm/IR/Instructions.h>
int main()
{
return 0;
}
I cat get these warnings by using either gcc or clang:
g++-9 -std=c++17 main.cpp -Wall -Wextra -I/usr/lib/llvm-9/include -c -o main.o
clang++-9 -std=c++17 main.cpp -Wall -Wextra -I/usr/lib/llvm-9/include -c -o main.o
They are mainly unused parameters:
In file included from /usr/lib/llvm-9/include/llvm/IR/ConstantFolder.h:20,
from /usr/lib/llvm-9/include/llvm/IR/IRBuilder.h:24,
from main.cpp:1:
/usr/lib/llvm-9/include/llvm/IR/Constants.h: In member function ‘llvm::Value* llvm::ConstantData::handleOperandChangeImpl(llvm::Value*, llvm::Value*)’:
/usr/lib/llvm-9/include/llvm/IR/Constants.h:60:41: warning: unused parameter ‘From’ [-Wunused-parameter]
60 | Value *handleOperandChangeImpl(Value *From, Value *To) {
| ~~~~~~~^~~~
/usr/lib/llvm-9/include/llvm/IR/Constants.h:60:54: warning: unused parameter ‘To’ [-Wunused-parameter]
60 | Value *handleOperandChangeImpl(Value *From, Value *To) {
| ~~~~~~~^~
In file included from /usr/lib/llvm-9/include/llvm/IR/ConstantFolder.h:21,
from /usr/lib/llvm-9/include/llvm/IR/IRBuilder.h:24,
from main.cpp:1:
/usr/lib/llvm-9/include/llvm/IR/InstrTypes.h: In member function ‘bool llvm::CallBase::isFnAttrDisallowedByOpBundle(llvm::StringRef) const’:
/usr/lib/llvm-9/include/llvm/IR/InstrTypes.h:1913:47: warning: unused parameter ‘S’ [-Wunused-parameter]
1913 | bool isFnAttrDisallowedByOpBundle(StringRef S) const {
| ~~~~~~~~~~^
In file included from /usr/lib/llvm-9/include/llvm/IR/IRBuilder.h:33,
from main.cpp:1:
/usr/lib/llvm-9/include/llvm/IR/Instructions.h: In member function ‘llvm::BasicBlock* llvm::ReturnInst::getSuccessor(unsigned int) const’:
/usr/lib/llvm-9/include/llvm/IR/Instructions.h:2943:37: warning: unused parameter ‘idx’ [-Wunused-parameter]
2943 | BasicBlock *getSuccessor(unsigned idx) const {
| ~~~~~~~~~^~~
...
I just truncate these warnings. They are too many.
When I turn on the -Wconversion the problem becomes even worse:
In file included from /usr/lib/llvm-9/include/llvm/Support/MathExtras.h:17,
from /usr/lib/llvm-9/include/llvm/ADT/SmallVector.h:19,
from /usr/lib/llvm-9/include/llvm/ADT/STLExtras.h:20,
from /usr/lib/llvm-9/include/llvm/ADT/StringRef.h:12,
from /usr/lib/llvm-9/include/llvm/ADT/StringMap.h:16,
from /usr/lib/llvm-9/include/llvm/Support/Host.h:16,
from /usr/lib/llvm-9/include/llvm/ADT/Hashing.h:48,
from /usr/lib/llvm-9/include/llvm/ADT/ArrayRef.h:12,
from /usr/lib/llvm-9/include/llvm/IR/IRBuilder.h:18,
from main.cpp:1:
/usr/lib/llvm-9/include/llvm/Support/SwapByteOrder.h: In function ‘uint16_t llvm::sys::SwapByteOrder_16(uint16_t)’:
/usr/lib/llvm-9/include/llvm/Support/SwapByteOrder.h:36:23: warning: conversion from ‘int’ to ‘uint16_t’ {aka ‘short unsigned int’} may change value [-Wconversion]
36 | uint16_t Hi = value << 8;
| ~~~~~~^~~~
/usr/lib/llvm-9/include/llvm/Support/SwapByteOrder.h:37:23: warning: conversion from ‘int’ to ‘uint16_t’ {aka ‘short unsigned int’} may change value [-Wconversion]
37 | uint16_t Lo = value >> 8;
| ~~~~~~^~~~
In file included from /usr/lib/llvm-9/include/llvm/ADT/STLExtras.h:20,
from /usr/lib/llvm-9/include/llvm/ADT/StringRef.h:12,
from /usr/lib/llvm-9/include/llvm/ADT/StringMap.h:16,
from /usr/lib/llvm-9/include/llvm/Support/Host.h:16,
from /usr/lib/llvm-9/include/llvm/ADT/Hashing.h:48,
from /usr/lib/llvm-9/include/llvm/ADT/ArrayRef.h:12,
from /usr/lib/llvm-9/include/llvm/IR/IRBuilder.h:18,
from main.cpp:1:
/usr/lib/llvm-9/include/llvm/ADT/SmallVector.h: In constructor ‘llvm::SmallVectorBase::SmallVectorBase(void*, size_t)’:
/usr/lib/llvm-9/include/llvm/ADT/SmallVector.h:45:35: warning: conversion from ‘size_t’ {aka ‘long unsigned int’} to ‘unsigned int’ may change value [-Wconversion]
45 | : BeginX(FirstEl), Capacity(TotalCapacity) {}
| ^~~~~~~~~~~~~
...
I get these warnings by clang too:
...
In file included from main.cpp:1:
In file included from /usr/lib/llvm-9/include/llvm/IR/IRBuilder.h:18:
In file included from /usr/lib/llvm-9/include/llvm/ADT/ArrayRef.h:12:
/usr/lib/llvm-9/include/llvm/ADT/Hashing.h:190:15: warning: implicit conversion changes signedness: 'const char' to 'uint8_t' (aka 'unsigned char') [-Wsign-conversion]
uint8_t a = s[0];
~ ^~~~
/usr/lib/llvm-9/include/llvm/ADT/Hashing.h:191:15: warning: implicit conversion changes signedness: 'const char' to 'uint8_t' (aka 'unsigned char') [-Wsign-conversion]
uint8_t b = s[len >> 1];
~ ^~~~~~~~~~~
/usr/lib/llvm-9/include/llvm/ADT/Hashing.h:192:15: warning: implicit conversion changes signedness: 'const char' to 'uint8_t' (aka 'unsigned char') [-Wsign-conversion]
uint8_t c = s[len - 1];
~ ^~~~~~~~~~
...
This is just a MWE. Adding more headers, I can get other types of warnings such as
/usr/lib/llvm-9/include/llvm/ADT/Twine.h:232:16: warning: ‘<anonymous>.llvm::Twine::RHS.llvm::Twine::Child::twine’ may be used uninitialized in this function [-Wmaybe-uninitialized]
!RHS.twine->isBinary())
~~~~^~~~~
Now, I am wondering whether LLVM is written carelessly? I always turn on all warnings and make sure my application compiles with 0 warnings. When I do this while using LLVM all warnings of my code are burried under LLVM ones. I cannot easily see them. Usually the first advise from people is to turn off those warnings switches. I strictly resist that. I want to find them for my application. The alternative solution comes to my mind is to turn off these warnings only for LLVM but not for my application. Is this possible especially when using CMake?
The issue of system header files causing warnings is a common one. It is not really for me to judge whether the authors of those headers were "careless" or not, but there is a relatively simple way to disable specific warnings before including the 'offending' headers, then restore your 'full' warnings once they have been included.
For clang you can do this with various #pragma diagnostic ... lines, as shown in the following code snippet:
#if defined (__clang__)
#pragma clang diagnostic push // Saves current diagnostic settings
#pragma clang diagnostic ignored "-Wsign-conversion" // Ignore this warning
#pragma clang diagnostic ignored "-Wunused-parameter" // and this one...
// ... Add similar lines for other warnings you wish to disable
#endif
// Now include the 'offending' headers ...
#include <llvm/IR/IRBuilder.h>
#include <llvm/IR/Verifier.h>
#include <llvm/Support/TargetSelect.h>
#include <llvm/ExecutionEngine/ExecutionEngine.h>
#include <llvm/IR/Instructions.h>
#if defined(__clang__)
#pragma clang diagnostic pop // Restores the saved settings
#endif
I don't have access to a GCC compiler but I believe very similar directives can be used: just substitute GCC for clang in the lines where that occurs. More information on such #pragma directives (for the GCC versions) can be found here.
It is dependent on your GCC/clang/OS installation. On Fedora 32 it works as expected out of the box with system gcc-10.2.1-1.fc32.x86_64 + system clang-10.0.0-2.fc32.x86_64:
#include <llvm/IR/IRBuilder.h>
#include <llvm/IR/Verifier.h>
#include <llvm/Support/TargetSelect.h>
#include <llvm/ExecutionEngine/ExecutionEngine.h>
#include <llvm/IR/Instructions.h>
static void func(int val) {}
int main()
{
func(42);
return 0;
}
For GCC:
$ g++ -o stackoverflowllvmwarnings stackoverflowllvmwarnings.C $(llvm-config --cflags --libs) -std=c++17 -Wall -Wextra
stackoverflowllvmwarnings.C: In function ‘void func(int)’:
stackoverflowllvmwarnings.C:7:22: warning: unused parameter ‘val’ [-Wunused-parameter]
7 | static void func(int val) {}
| ~~~~^~~
$ _
For clang:
$ clang++ -o stackoverflowllvmwarnings stackoverflowllvmwarnings.C $(llvm-config --cflags --libs) -std=c++17 -Wall -Wextra
stackoverflowllvmwarnings.C:7:22: warning: unused parameter 'val' [-Wunused-parameter]
static void func(int val) {}
^
1 warning generated.
$ _
If you really want (you do not) the warnings even for system headers use Wsystem-headers (it works similar way both for gcc and clang):
$ clang++ -o stackoverflowllvmwarnings stackoverflowllvmwarnings.C $(llvm-config --cflags --libs) -std=c++17 -Wall -Wextra -Wsystem-headers
In file included from stackoverflowllvmwarnings.C:1:
In file included from /usr/include/llvm/IR/IRBuilder.h:17:
In file included from /usr/include/llvm-c/Types.h:17:
In file included from /usr/include/llvm-c/DataTypes.h:28:
In file included from /usr/bin/../lib/gcc/x86_64-redhat-linux/10/../../../../include/c++/10/cmath:42:
/usr/bin/../lib/gcc/x86_64-redhat-linux/10/../../../../include/c++/10/bits/cpp_type_traits.h:110:12: warning: keyword '__is_void' will be made available as an identifier for the remainder of the translation unit [-Wkeyword-compat]
struct __is_void
^
...
Consider the following code:
#include <complex>
int main()
{
unsigned u = 1u;
auto result = static_cast<std::complex<int>>(u);
return 0;
}
Compiling with
g++ -std=c++11 -Werror -Wsign-conversion -o a.out source_file.cpp
Causes compile error
source_file.cpp: In function ‘int main()’:
source_file.cpp:8:51: error: conversion to ‘int’ from ‘unsigned int’ may change the sign of the result [-Werror=sign-conversion]
auto result = static_cast<std::complex<int>>(u);
^
clang reports a similar error
source_file.cpp:6:50: error: implicit conversion changes signedness: 'unsigned int' to 'const value_type' (aka 'const int') [-Werror,-Wsign-conversion]
auto result = static_cast<std::complex<int>>(u);
~~~~~~~~~~~ ^
The error does not make much sense at first sight, what am I missing?
You get a conversion warning not from the cast, but from inside construction of std::complex.
To 'fix' your example you should instead do:
auto result = std::complex<int>{static_cast<int>(u)};
I'm trying to compile the following code:
#include <boost/optional.hpp>
void foo(boost::optional<unsigned> x = boost::none);
placed in the file a.cu, with the CUDA compiler, using the following command line:
nvcc a.cu -c --std=c++11 -I/opt/boost/include
but I get a bunch of errors:
a.cu:2:53: error: conversion from ‘const boost::none_t(boost::none_t::init_tag (*)())’ to ‘boost::optional<unsigned int>’ is ambiguous
void foo(boost::optional<unsigned> x = boost::none);
^
/opt/boost/include/boost/optional/optional.hpp:805:1: note: candidate: boost::optional<T>::optional(boost::optional<T>::rval_reference_type) [with T = unsigned int; boost::optional<T>::rval_reference_type = unsigned int&&] <near match>
optional ( rval_reference_type val ) : base( boost::forward<T>(val) )
^ ~~~~
/opt/boost/include/boost/optional/optional.hpp:805:1: note: conversion of argument 1 would be ill-formed:
a.cu:2:53: error: invalid conversion from ‘const boost::none_t (*)(boost::none_t::init_tag (*)())’ to ‘unsigned int’ [-fpermissive]
void foo(boost::optional<unsigned> x = boost::none);
^
/opt/boost/include/boost/optional/optional.hpp:800:1: note: candidate: boost::optional<T>::optional(boost::optional<T>::argument_type) [with T = unsigned int; boost::optional<T>::argument_type = const unsigned int&] <near match>
optional ( argument_type val ) : base(val) {}
^ ~~~~
/opt/boost/include/boost/optional/optional.hpp:800:1: note: conversion of argument 1 would be ill-formed:
a.cu:2:53: error: invalid conversion from ‘const boost::none_t (*)(boost::none_t::init_tag (*)())’ to ‘unsigned int’ [-fpermissive]
void foo(boost::optional<unsigned> x = boost::none);
Why does this happen, and can I circumvent the problem while still actually using boost::optional in (host-side) code compiled with nvcc?
Additional information:
The code compiles fine with g++ 6.3.0 (my distribution's compiler).
This code (or rather, similar code) used to compile and work on an earlier Linux distribution I was using, where the compiler was g++ 5.4.x .
I've tried this with Boost versions 1.65.1 and 1.69.0 .
I've tried this with CUDA versions 9.2.88 and 10.0.130 .
I had the exact same error and was able to get this to work with this modification:
#define BOOST_OPTIONAL_USE_OLD_DEFINITION_OF_NONE
#include <boost/optional.hpp>
This is using CUDA 10.0.130, g++ 7.3.0, and Boost 1.68.0.
A partial answer to the second question:
You could consider using Andrzej Krzemieński's neat and self-contained implementation of an optional instead of boost::optional. It works with C++11, which is what you seem to be doing.
So I thought I installed GDAL correctly using aptitude, and all my makefile has is
` g++ main.cpp -I/usr/include/mysql -lmysqlclient -I/usr/include/gdal -lgdal1.7.0'
But I am getting this error on my make "ubuntu vm"
`g++ main.cpp -I/usr/include/mysql -lmysqlclient -I/usr/include/gdal -lgdal1.7.0
In file included from /usr/include/c++/4.6/vector:65:0,
from /usr/include/gdal/gdal_priv.h:58,
from main.cpp:5:
/usr/include/c++/4.6/bits/stl_vector.h: In member function ‘std::vector<_Tp, _Alloc>::size_type std::vector<_Tp, _Alloc>::_M_check_len(std::vector<_Tp, _Alloc>::size_type, const char*) const’:
/usr/include/c++/4.6/bits/stl_vector.h:1244:40: error: expected unqualified-id before ‘(’ token
In file included from /usr/include/c++/4.6/vector:66:0,
from /usr/include/gdal/gdal_priv.h:58,
from main.cpp:5:
/usr/include/c++/4.6/bits/stl_bvector.h: In member function ‘std::vector<bool, _Alloc>::size_type std::vector<bool, _Alloc>::_M_check_len(std::vector<bool, _Alloc>::size_type, const char*) const’:
/usr/include/c++/4.6/bits/stl_bvector.h:1026:45: error: expected unqualified-id before ‘(’ token
make: *** [all] Error 1
`
Don't really know how to solve this one
Here is all my code:
#include <iostream>
#include "sql.h"
#include "gdal_priv.h"
#include "cpl_conv.h"
int main(int argc, char ** argv){
GDALDataset *poDataset;
return 0;
}
This looks more like an STL/vector issue than a GDAL specific problem. Something is going wrong when gdal_priv.h does
#include <vector>
I'd first check if you can compile something like this:
#include <vector>
int main(int argc, char ** argv){
std::vector<int> foo;
}
In the following code from Stroustrup's book we are warned against an error from a narrowing conversion which does not occur on my version GCC (4.7.2)
#include <iostream>
using namespace std;
int main()
{
int i1 = 7.2;
int i2{7.2};
cout << i1 << " " << i2 << endl;
return 0;
}
As demonstrated here at ideone is this a bug or am I not running with the appropriate command line arguments to the compiler? Or is this meant to be a purely semantic error?
With g++ 4.8.1:
foo.cpp: In function 'int main()':
foo.cpp:8:15: warning: narrowing conversion of '7.2000000000000002e+0' from 'double' to 'int' inside { } [-Wnarrowing]
int i2{7.2};
^
I assume it's simply a bug in 4.7.2's c++11 support.
I get a narrowing warning with GCC 4.7.3 when I use -std=c++0x:
g++ -std=c++0x test.cpp
test.cpp: In function ‘int main()’:
test.cpp:8:23: warning: narrowing conversion of ‘7.2000000000000002e+0’ from ‘double’ to ‘int’ inside { } [-Wnarrowing]
g++ --version
g++ (GCC) 4.7.3