I am currently porting my compiler from AIX XLC compiler to GCC compiler on AIX.
I want to know if there is an GCC equivalent compiler option available for the -qthreaded (XLC).
-pthread is the closest GCC option for use cases where -qthreaded is applied for XL; however, it is not equivalent to the -qthreaded option for IBM XL.
The GCC documentation for -pthread merely states that it sets macros (http://gcc.gnu.org/onlinedocs/gcc/Preprocessor-Options.html#index-pthread) and modifies the link step (http://gcc.gnu.org/onlinedocs/gcc/Link-Options.html#index-pthread-1). -qthreaded does not cause _THREAD_SAFE to be defined as a macro, nor does it cause -lpthreads to be present in the link step. GCC's -pthread is more like XL's _r invocations (which does set the macro and modify the link step).
What -qthreaded does is to disable optimizations that are unsafe for multithreaded programs. It appears that, at least historically, -fno-tree-loop-if-convert-stores would at least partially be a GCC equivalent to -qthreaded.
I'm trying to setup codelite using the GCC compiler. I'm trying to add the switches:
-fno-pie -no-pie
This works when using gcc in the terminal.
Below is where I have placed the switches.I have done this for the cross GCC (i686) aswell.
This doesn't seem to be working though. My disassembly doesn't seem to be the same as when I use gcc in my terminal to compile with the -fno-pie and -no-pie
How do I get this to work?
Thanks for any help.
You have gone from the IDE's top menubar through Settings -> Build Settings -> Compilers -> GCC -> Compiler Options -> New..., and added options
-fno-pie and -no-pie
What you have done is edited the global compiler options for GCC that CodeLite will make available to be enabled or disabled
in the Compiler options dialog of any project that uses the GCC compiler. You have not actually enabled either of those
options for any particular project that uses GCC.
The globally configured compiler options for GCC (or other compiler) are by default the
most commonly wanted ones. There is no need to edit this configuration to use any
other compiler options in a project. If you do edit the configuration to make them
available, then you also need to enable them in the project Settings of GCC projects
in which you want them enabled.
-fpie|-fno-pie are compilation options. -pie|-no-pie are not compilation options: they are
linkage options. If you wanted to make these linkage options available in all GCC projects
then you would proceed through Settings -> Build Settings -> Compilers -> GCC -> Linker Options -> New...
To add -fno-pie to the compiler settings of a GCC project MyProj, from the workspace
tree-view, navigate MyProj -> Settings -> {Debug|Release} -> Compiler -> {C++|C} Compiler Options.
Then, if you have not bothered to edit the GCC compiler options configuration, just
edit the edit-field on the right - probably already containing default compiler options such
as -g;-O0;-Wall - and append ;-fno-pie to whatever is there. If you have bothered
to add -fno-pie to the configured compiler options, then click on the '...' button
at the right of the edit-field, and select -fno-pie from the Compiler Options.
To add -no-pie to the linker settings of a GCC project MyProj, from the workspace
tree-view, navigate MyProj -> Settings -> {Debug|Release} -> Linker -> Linker Options
and apply -no-pie in the same way as you applied -fno-pie for the compiler options.
I'm writing some code that requires to have C++11 support for my Code::Blocks 12.11. I am using default GNU GCC Compiler came with MingW. Is there any way I can do this?
Go to Toolbar -> Settings -> Compiler
In the Selected compiler drop-down menu, make sure GNU GCC Compiler is selected
Below that, select the compiler settings tab and then the compiler flags tab underneath
In the list below, make sure the box for "Have g++ follow the C++11 ISO C++ language standard [-std=c++11]" is checked
Click OK to save
The answer with screenshots (put the checkbox as in the second pic, then press OK):
A simple way is to write:
-std=c++11
in the Other Options section of the compiler flags. You could do this on a per-project basis (Project -> Build Options), and/or set it as a default option in the Settings -> Compilers part.
Some projects may require -std=gnu++11 which is like C++11 but has some GNU extensions enabled.
If using g++ 4.9, you can use -std=c++14 or -std=gnu++14.
Use g++ -std=c++11 -o <output_file_name> <file_to_be_compiled>
I'm using Kdevelop for a simple C++ project. I know that Kdevelop uses CMake to build the project, but the only thing that I known about CMake is that if I add a new .cpp source file in my project, I have to add it also in CMakeLists.txt.
Now I'm trying to enable tha gcc compiler warnings (i.e. compiling with g++ -Wall ...).
Does Kdevelop have a compiler settings section, or I have to edit directly the Makefile or another CMake settings file?
You can add compiler flags in CMake by adding the following command to your CMakeLists.txt:
list( APPEND CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall")
When I try to run a CMake generated makefile to compile my program, I get the error that
range based for loops are not supported in C++ 98 mode.
I tried adding add_definitions(-std=c++0x) to my CMakeLists.txt, but it did not help.
I tried this too:
if(CMAKE_COMPILER_IS_GNUCXX)
add_definitions(-std=gnu++0x)
endif()
When I do g++ --version, I get:
g++ (Ubuntu/Linaro 4.6.1-9ubuntu3) 4.6.1
I have also tried SET(CMAKE_CXX_FLAGS "-std=c++0x"), which also does not work.
I do not understand how I can activate C++ 11 features using CMake.
CMake 3.1 introduced the CMAKE_CXX_STANDARD variable that you can use. If you know that you will always have CMake 3.1 or later available, you can just write this in your top-level CMakeLists.txt file, or put it right before any new target is defined:
set (CMAKE_CXX_STANDARD 11)
If you need to support older versions of CMake (quite unlikely these days), here is a macro I came up with that you can use:
macro(use_cxx11)
if (CMAKE_VERSION VERSION_LESS "3.1")
if (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=gnu++11")
endif ()
else ()
set (CMAKE_CXX_STANDARD 11)
endif ()
endmacro(use_cxx11)
The macro only supports GCC right now, but it should be straight-forward to expand it to other compilers.
Then you could write use_cxx11() at the top of any CMakeLists.txt file that defines a target that uses C++11.
CMake issue #15943 for clang users targeting macOS
If you are using CMake and clang to target macOS there is a bug that can cause the CMAKE_CXX_STANDARD feature to simply not work (not add any compiler flags). Make sure that you do one of the following things:
Use cmake_minimum_required to require CMake 3.0 or later, or
Set policy CMP0025 to NEW with the following code at the top of your CMakeLists.txt file before the project command:
# Fix behavior of CMAKE_CXX_STANDARD when targeting macOS.
if (POLICY CMP0025)
cmake_policy(SET CMP0025 NEW)
endif ()
The CMake command target_compile_features() is used to specify the required C++ feature cxx_range_for. CMake will then induce the C++ standard to be used.
cmake_minimum_required(VERSION 3.1.0 FATAL_ERROR)
project(foobar CXX)
add_executable(foobar main.cc)
target_compile_features(foobar PRIVATE cxx_range_for)
There is no need to use add_definitions(-std=c++11) or to modify the CMake variable CMAKE_CXX_FLAGS, because CMake will make sure the C++ compiler is invoked with the appropriate command line flags.
Maybe your C++ program uses other C++ features than cxx_range_for. The CMake global property CMAKE_CXX_KNOWN_FEATURES lists the C++ features you can choose from.
Instead of using target_compile_features() you can also specify the C++ standard explicitly by setting the CMake properties
CXX_STANDARD
and
CXX_STANDARD_REQUIRED for your CMake target.
See also my more detailed answer.
I am using
include(CheckCXXCompilerFlag)
CHECK_CXX_COMPILER_FLAG("-std=c++11" COMPILER_SUPPORTS_CXX11)
CHECK_CXX_COMPILER_FLAG("-std=c++0x" COMPILER_SUPPORTS_CXX0X)
if(COMPILER_SUPPORTS_CXX11)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
elseif(COMPILER_SUPPORTS_CXX0X)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++0x")
else()
message(STATUS "The compiler ${CMAKE_CXX_COMPILER} has no C++11 support. Please use a different C++ compiler.")
endif()
But if you want to play with C++11, g++ 4.6.1 is pretty old.
Try to get a newer g++ version.
The easiest way to set the Cxx standard is:
set_property(TARGET tgt PROPERTY CXX_STANDARD 11)
See the CMake documentation for more details.
On modern CMake (>= 3.1) the best way to set global requirements is:
set(CMAKE_CXX_STANDARD 11)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_CXX_EXTENSIONS OFF)
It translates to "I want C++11 for all targets, it's not optional, I don’t want to use any GNU or Microsoft extensions."
As of C++17, this still is IMHO the best way.
Source: Enabling C++11 And Later In CMake
As it turns out, SET(CMAKE_CXX_FLAGS "-std=c++0x") does activate many C++11 features. The reason it did not work was that the statement looked like this:
set(CMAKE_CXX_FLAGS "-std=c++0x ${CMAKE_CXX_FLAGS} -g -ftest-coverage -fprofile-arcs")
Following this approach, somehow the -std=c++0x flag was overwritten and it did not work. Setting the flags one by one or using a list method is working.
list( APPEND CMAKE_CXX_FLAGS "-std=c++0x ${CMAKE_CXX_FLAGS} -g -ftest-coverage -fprofile-arcs")
For CMake 3.8 and newer you can use
target_compile_features(target PUBLIC cxx_std_11)
If you want the generation step to fail if the toolchain cannot adhere to this standard, you can make this required.
set_target_properties(target PROPERTIES CXX_STANDARD_REQUIRED ON)
If you want strict adherence to standard C++ i.e. avoid C++ extensions offered by your compiler (like GCC's -std=gnu++17), additionally set
set_target_properties(target PROPERTIES CXX_EXTENSIONS OFF)
This is documented in detail at An Introduction to Modern CMake -> Adding Features -> C++11 and Beyond. It also offers advice on how to achieve this on older versions of CMake if you're constrained to those.
The easiest way:
add_compile_options(-std=c++11)
This is another way of enabling C++11 support,
ADD_DEFINITIONS(
-std=c++11 # Or -std=c++0x
# Other flags
)
I have encountered instances where only this method works and other methods fail. Maybe it has something to do with the latest version of CMake.
Modern cmake offers simpler ways to configure compilers to use a specific version of C++. The only thing anyone needs to do is set the relevant target properties. Among the properties supported by cmake, the ones that are used to determine how to configure compilers to support a specific version of C++ are the following:
CXX_STANDARD sets the C++ standard whose features are requested to build the target. Set this as 11 to target C++11.
CXX_EXTENSIONS, a boolean specifying whether compiler specific extensions are requested. Setting this as Off disables support for any compiler-specific extension.
To demonstrate, here is a minimal working example of a CMakeLists.txt.
cmake_minimum_required(VERSION 3.1)
project(testproject LANGUAGES CXX )
set(testproject_SOURCES
main.c++
)
add_executable(testproject ${testproject_SOURCES})
set_target_properties(testproject
PROPERTIES
CXX_STANDARD 11
CXX_EXTENSIONS off
)
In case you want to always activate the latest C++ standard, here's my extension of David Grayson's answer, in light of the recent (CMake 3.8 and CMake 3.11) additions of values of 17 and 20 for CMAKE_CXX_STANDARD):
IF (CMAKE_VERSION VERSION_LESS "3.8")
SET(CMAKE_CXX_STANDARD 14)
ELSEIF (CMAKE_VERSION VERSION_LESS "3.11")
SET(CMAKE_CXX_STANDARD 17)
ELSE()
SET(CMAKE_CXX_STANDARD 20)
ENDIF()
# Typically, you'll also want to turn off compiler-specific extensions:
SET(CMAKE_CXX_EXTENSIONS OFF)
(Use that code in the place of set (CMAKE_CXX_STANDARD 11) in the linked answer.)
What works for me is to set the following line in your CMakeLists.txt:
set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
Setting this command activates the C++11 features for the compiler and after executing the cmake .. command, you should be able to use range based for loops in your code and compile it without any errors.
I think just these two lines are enough.
set(CMAKE_CXX_STANDARD 11)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
The modern way is to specify the minimum required standard to C++11 with:
target_compile_features(foo PUBLIC cxx_std_11)
This way:
CMake can honor default C++ standard of the compiler if it's greater than C++11
You can clearly specify whether C++ standard is required at build time, consume time, or both. This is nice for libraries.
Public compile features are propagated to downstream targets, so it comes for free in those targets even if they don't directly use this feature.
Users can externally set another C++ standard (more recent basically), with CMAKE_CXX_STANDARD, either from command line or CMake presets. If you hardcode CMAKE_CXX_STANDARD in a CMakeLists, nobody can override the C++ standard without editing your CMakeLists, which is not very pleasant.
It requires CMake >= 3.8
You can use the following. This automatically modifies the feature based on your environment.
target_compile_features(your_target INTERFACE cxx_std_20)
For example,
on Gnu/Linux the following adds -std=gnu++20
on Windows with Clang/Ninja it becomes -std=c++20
on Windows with MSVC it becomes /std=c++20
So you support as many as environments possible.
In case you stumble on that same error using cmake as i did.
You need to set
set (CMAKE_CXX_STANDARD 11)
to activate threading because it is only supported from c++11 ++
hope that helps
OS X and Homebrew LLVM related:
Don't forget to call cmake_minimum_required(VERSION 3.3) and project() after it!
Or CMake will insert project() implicitly before line 1, causing trouble with Clang version detection and possibly other sorts of troubles. Here is a related issue.