I am running a CMake (3.4.3) like this as explained in the CMake FAQ's:
export CC="cc_args.py $PWD/../bin/gcc"
export CXX="cc_args.py $PWD/../bin/g++"
cmake -DCMAKE_BUILD_TYPE=Debug ..
However when I print CMAKE_CXX_COMPILER and CMAKE_C_COMPILER it still points to the system's default compilers in /usr/bin. It only works when I explicitly read-in the environment variables like this:
IF (NOT $ENV{CC} STREQUAL "")
SET(CMAKE_C_COMPILER $ENV{CC})
ENDIF ()
IF (NOT $ENV{CXX} STREQUAL "")
SET(CMAKE_CXX_COMPILER $ENV{CXX})
ENDIF ()
But even then the building fails with this message:
/bin/sh: 1: /home/peterg/bin/cc_args.py /home/peterg/Code/build/../bin/g++: not found
However I am certain that all paths are correct since executing just the path between the two colons outputs this as expected:
g++: fatal error: no input files
compilation terminated.
Update:
It seems the compiling process does not like spaces in the compiler paths. I've now created two scripts (one for GCC and one for CC) which wrap the commands and propagate the arguments and that seems to work. But it still seems I am doing something fundamentally wrong because CMake would also not accept the exported CC=proxy_script_cc.sh and GCC=proxy_script_gcc.sh variables without spaces by itself.
Turning my comment into an answer
Problem
I've given you code a try and could reproduce your problem
CMake Error at [...]/cmake-3.5/Modules/CMakeDetermineCXXCompiler.cmake:56 (message):
Could not find compiler set in environment variable CXX:
cc_args.py [... PWD ...]/../bin/g++.
If I look at CMakeDetermineCXXCompiler.cmake code and at get_filename_component() documentation, it just means that it didn't find cc_args.py in "the system search path" or relative to your binary output directory.
Solution
So it does work when you give a full path or a relative path to your binary output dir with something like
export CC="../cc_args.py ../bin/gcc"
export CXX="../cc_args.py ../bin/g++"
Alternative
CMake does allow to define "launcher scripts" e.g. with CMAKE_<LANG>_COMPILER_LAUNCHER
$ cmake -DCMAKE_BUILD_TYPE=Debug
-DCMAKE_C_COMPILER_LAUNCHER=../cc_args.py
-DCMAKE_CXX_COMPILER_LAUNCHER=../cc_args.py
..
References
How to Use CCache with CMake?
Save and reprint warnings for successfully-compiled files on subsequent builds?
Pass -DCMAKE_CXX_COMPILER=<path/to/compiler> to your CMake call. That's less error prone compared to fiddling with shell variables.
Related
I want to set compiler path (for example:icc) automatically in cmake, so my program can compile at any computer as long as it have installed icc, and we do not need to care about where the icc is installed.
At First, I using the follow command to set compiler. Everything is OK.
set(Intel_C_COMPILER "/opt/intel/compilers_and_libraries_2019.0.117/linux/bin/intel64/icc")
set(Intel_CXX_COMPILER "/opt/intel/compilers_and_libraries_2019.0.117/linux/bin/intel64/icpc")
set(CMAKE_C_COMPILER ${Intel_C_COMPILER} )
set(CMAKE_CXX_COMPILER ${Intel_CXX_COMPILER})
project(MyProject)
....
Then, I want to set compiler path automatically, I know that the follow command can find compiler path
which icc
So I write the follow command try to set compiler automatically by cmake.
execute_process(COMMAND which icc OUTPUT_VARIABLE Intel_C_COMPILER)
execute_process(COMMAND which icpc OUTPUT_VARIABLE Intel_CXX_COMPILER)
message(Intel_CXX_COMPILER: ${Intel_C_COMPILER})
message(Intel_CXX_COMPILER: ${Intel_CXX_COMPILER})
set(CMAKE_C_COMPILER ${Intel_C_COMPILER} )
set(CMAKE_CXX_COMPILER ${Intel_CXX_COMPILER})
project(MyProject)
....
At these case, something strange happens, cmake shows that:
Intel_CXX_COMPILER:/opt/intel/compilers_and_libraries_2019.0.117/linux/bin/intel64/icpc
-- The C compiler identification is unknown
-- The CXX compiler identification is unknown
CMake Error at CMakeLists.txt:27 (project): The CMAKE_C_COMPILER:
/opt/intel/compilers_and_libraries_2019.0.117/linux/bin/intel64/icc
is not a full path to an existing compiler tool.
Tell CMake where to find the compiler by setting either the
environment variable "CC" or the CMake cache entry CMAKE_C_COMPILER
to the full path to the compiler, or to the compiler name if it is
in the PATH.
CMake Error at CMakeLists.txt:27 (project): The CMAKE_CXX_COMPILER:
/opt/intel/compilers_and_libraries_2019.0.117/linux/bin/intel64/icpc
is not a full path to an existing compiler tool.
Tell CMake where to find the compiler by setting either the
environment variable "CXX" or the CMake cache entry
CMAKE_CXX_COMPILER to the full path to the compiler, or to the
compiler name if it is in the PATH.
-- Configuring incomplete, errors occurred!
CMake said that the path is not a full path to an existing compiler, but as shown in the message, it is just where the compiler located!
I know there are other techniques that we can set compiler, for example export some environment variables to help cmake find the path, but I want to know why my method dose not work?
Is there any better way can handle this problem?
Thanks in advance.
Variables Intel_C_COMPILER and Intel_CXX_COMPILER have trailing newline. Way for removing that newline are described in that question and its answers: How to strip trailing whitespace in CMake variable?
E.g., you may run execute_process with OUTPUT_STRIP_TRAILING_WHITESPACE option, so it will behave similar to the shell's backtick operator (`which icc`).
Detailed description
Most of shell utilities output single- (or even multi-) line information with trailing newline. And utility which is not an exception. With trailing newline an output looks nice when one run these utilities in the terminal.
But when run such utility in the script and grab its output programmatically, one need to care about such newline.
Generally speaking, it is not possible to set the variables CMAKE_C_COMPILER and CMAKE_CXX_COMPILER from within a project.
Since the compiler detection happens with the project() call, the compiler has to be set early on while configuring the project.
I suggest you try the following:
export CC=/opt/intel/compilers_and_libraries_2019.0.117/linux/bin/intel64/icc
export CXX=/opt/intel/compilers_and_libraries_2019.0.117/linux/bin/intel64/icpc
cd /path/to/build
cmake /path/to/src
or you could also pass the variables CMAKE_C_COMPILER and CMAKE_CXX_COMPILER:
export CC=/opt/intel/compilers_and_libraries_2019.0.117/linux/bin/intel64/icc
export CXX=/opt/intel/compilers_and_libraries_2019.0.117/linux/bin/intel64/icpc
cd /path/to/build
cmake \
-DCMAKE_C_COMPILER:FILEPATH=/opt/intel/compilers_and_libraries_2019.0.117/linux/bin/intel64/icc \
-DCMAKE_CXX_COMPILER:FILEPATH=/opt/intel/compilers_and_libraries_2019.0.117/linux/bin/intel64/icpc \
/path/to/src
Important: When trying these commands, make sure to configure the project in an empty build directory.
I would like to investigate why I have this error:
$ cmake ..
-- The C compiler identification is unknown
-- The CXX compiler identification is GNU 5.4.0
-- Check for working C compiler: /cygdrive/c/Users/Ycr/Home/bin/arm-none-eabi-gcc
-- Check for working C compiler: /cygdrive/c/Users/Ycr/Home/bin/arm-none-eabi-gcc -- broken
CMake Error at /usr/share/cmake-3.6.2/Modules/CMakeTestCCompiler.cmake:61 (message):
The C compiler "/cygdrive/c/Users/Ycr/Home/bin/arm-none-eabi-gcc" is not
able to compile a simple test program.
Unfortunately after the error:
I have no idea of what CMake did. I don't have a verbose log of the command it executed.
The CMakeFiles/cmTC_e4aa4.dir was cleaned after the error, so I have no possibility to explore the issue myself.
How should I investigate such an error?
I tried to use the --debug-trycompile option. This time CMake creates a CMakeTmp folder which makes perfectly without errors. However, I still have this CMakeFiles/cmTC_e4aa4.dir that generates errors and even with the option CMake unlinks the folder.
Getting a Verbose Log
The try_compile() calls that CMake does in the beginning to test the compiler, gives a detailed error output on the console and writes it to
[your binary output directory]/CMakeFiles/CMakeError.log
I've checked the source code again and there is no CMake option that would give more a more detailed output for CMake's internal try_compile() calls.
You could just force the output to standard output by adding some variable_watch() calls to your main CMakeLists.txt before your project() call like:
variable_watch(__CMAKE_C_COMPILER_OUTPUT)
variable_watch(__CMAKE_CXX_COMPILER_OUTPUT)
Keeping the Temporary Files
To keep the temporary file of try_compile, add --debug-trycompile to the cmake command line.
But be aware that the multiple compiler tests at the beginning overwrite the artifacts of previous ones:
It may however change the results of the try-compiles as old junk from a previous try-compile may cause a different test to either pass or fail incorrectly. This option is best used for one try-compile at a time, and only when debugging.
References
How to keep generated temporary files?
CMake error at CMakeLists.txt:30 (project): No CMAKE_C_COMPILER could be found
For me, none of the log files in my output directory contained useful information from try_compile(), even when using --debug-trycompile.
I ended up using the OUTPUT_VARIABLE option to capture and then print the output like this:
try_compile(<options> OUTPUT_VARIABLE TRY_COMPILE_OUTPUT)
message(WARNING ${TRY_COMPILE_OUTPUT})
I am attempting to follow the tutorial here for developing a "Hello, World" LLVM pass - I am using the guidelines linked by that tutorial here for doing so out of the LLVM source directory. However, when I attempt to follow this tutorial, CMake reports a number of errors internal to LLVM itself.
I have the following directory structure:
HelloWorld/
CMakeLists.txt
HelloWorld/
CMakeLists.txt
HelloWorld.cpp
My HelloWorld.cpp, and the two CMakeLists.txt are copy and pasted directly from the tutorials linked to above.
I run CMake HelloWorld and it successfully generates a CMake configuration. However, when I run make. I get numerous errors reported from within the LLVM codebase itself.
[ 50%] Building CXX object CMakeFiles/LLVMPassName.dir/Vectorize.cpp.o
In file included from /Volumes/andromeda/HelloWorld/HelloWorld.cpp:1:
In file included from /usr/local/Cellar/llvm/3.6.2/include/llvm/Pass.h:377:
In file included from /usr/local/Cellar/llvm/3.6.2/include/llvm/PassSupport.h:27:
In file included from /usr/local/Cellar/llvm/3.6.2/include/llvm/PassRegistry.h:20:
In file included from /usr/local/Cellar/llvm/3.6.2/include/llvm-c/Core.h:18:
In file included from /usr/local/Cellar/llvm/3.6.2/include/llvm-c/Support.h:17:
/usr/local/Cellar/llvm/3.6.2/include/llvm/Support/DataTypes.h:57:3: error: "Must #define
__STDC_LIMIT_MACROS before #including Support/DataTypes.h"
# error "Must #define __STDC_LIMIT_MACROS before #including Support/DataTypes.h"
^
/usr/local/Cellar/llvm/3.6.2/include/llvm/Support/DataTypes.h:61:3: error: "Must #define
__STDC_CONSTANT_MACROS before " "#including Support/DataTypes.h"
# error "Must #define __STDC_CONSTANT_MACROS before " \
The list goes on and on and all of them refer to errors in LLVM header files. This is a clean install of LLVM using Homebrew. To get linking to work, I had to set CPLUS_INCLUDE_PATH to the Homebrew include directory for LLVM.
My first thought was that CMake was attempting to use a different compiler (Clang vs. GCC or vice versa), but setting CMAKE_CXX_COMPILER to point to either my clang or g++ installation did not help.
Does anyone have any ideas for what might be the problem here?
After following the link provided by #oak in the comments, I was able to get rid of the first two Support/DataType errors. However, many of the errors still remain.
In file included from /usr/local/Cellar/llvm/3.6.2/include/llvm/Pass.h:377:
In file included from /usr/local/Cellar/llvm/3.6.2/include/llvm/PassSupport.h:27:
In file included from /usr/local/Cellar/llvm/3.6.2/include/llvm/PassRegistry.h:21:
/usr/local/Cellar/llvm/3.6.2/include/llvm/ADT/DenseMap.h:543:63: error: a space is required
between consecutive right angle brackets (use '> >')
typename BucketT = detail::DenseMapPair<KeyT, ValueT>>
^
/usr/local/Cellar/llvm/3.6.2/include/llvm/ADT/DenseMap.h:694:63: error: a space is required
between consecutive right angle brackets (use '> >')
typename BucketT = detail::DenseMapPair<KeyT, ValueT>>
So, after much research, it turns out that there is an inconsistency with how LLVM and CMake support out-of-source builds. The LLVM binaries are built with -fno-rtti, so CMake will complain about missing symbols unless it is also uses -fno-rtti when compiling the LLVM pass.
I fixed all of my troubles (including those solved by the temporary fix proposed by Oak) by adding SET(CMAKE_CXX_FLAGS "-Wall -fno-rtti") to my CMakeLists.txt file in the innermost directory.
This was inspired by this question also on StackOverflow.
Suppose I have a package called Foo. If I run CMake on a CMakeLists.txt file that contains find_package(Foo), then I can print out the values of variables such as ${Foo_LIBRARIES} and ${Foo_INCLUDES}.
Is there an easy way to display these variables without having to run CMake on a CMakeLists.txt file, and without having to manually inspect the config.cmake file?
You asked: (1) Is there an easy way to display these variables without having to run cmake on a CMakeLists.txt file, and (2) without having to manually inspect the config.cmake file?
I can give you a yes answer to (2) but it does require that you (re)run cmake. But since you can re-run your cmake configure step by simply executing cmake . in the build directory, re-running cmake should not keep you from trying this approach. My answer is given in this SO answer and uses the get_cmake_property command. Here is that code encapsulated into a cmake macro, print_all_variables, so I can use it when debugging my cmake scripts.
macro(print_all_variables)
message(STATUS "print_all_variables------------------------------------------{")
get_cmake_property(_variableNames VARIABLES)
foreach (_variableName ${_variableNames})
message(STATUS "${_variableName}=${${_variableName}}")
endforeach()
message(STATUS "print_all_variables------------------------------------------}")
endmacro()
The macros are invoked with same syntax as cmake functions:
print_all_variables()
To simply print a value, you could do something like this:
message(STATUS "foo include dir: ${foo_INCLUDE}")
where ${foo_INCLUDE} is the value you desire to print.
Note: I'm using cmake > 3.14
Run CMake and have a look at the cache with the ccmake GUI tool. Then you'll get all the variables.
Or run CMake with -LH then you will get all variables printed after configuration.
So I think it is not possible to get the variables without running CMake.
Run cmake in find-package mode. Example to display a package`s include directories:
cmake -DNAME=ZLIB -DCOMPILER_ID=GNU -DLANGUAGE=C -DMODE=COMPILE --find-package
Example to display the libraries:
cmake -DNAME=ZLIB -DCOMPILER_ID=GNU -DLANGUAGE=C -DMODE=LINK --find-package
The NAME must be set to the package name. You can obtain your COMPILER_ID on this page. LANGUAGE can be C, CXX or Fortran.
I am always suspicious of variables changing values throughout a script somewhere so I like to see the value of a variable at a particular point in the running script. Combining the ideas from both Phil and Aaron B. this is what I'm using:
function(PRINT_VAR VARNAME)
message(STATUS "${VARNAME}: ${${VARNAME}}")
endfunction()
PRINT_VAR("CMAKE_CXX_COMPILER")
Then I can just litter PRINT_VAR statements around like I'm debugging code back in 1980
These variables are generally hardcoded into FindFoo.cmake so that it is not possible to extract them without running the function first. Note that sometimes the value of Foo_LIBRARIES depends on the system configuration, which is unknown until find_package(Foo) is run.
I have two projects using CMake.
The first is a shared library. It compiles and installs fine. Currently, it is still necessary to build 'debug' releases of it. So presently it is installed under ~/localdebug. That folder looks like the root of a filesystem with a 'include' and 'lib' directory. The same concept as '/usr/local'.
The second is a program. It needs to compile and link against my library in ~/localdebug. The CMakeLists.txt file for it looks like this:
cmake_minimum_required(VERSION 2.6)
set(CMAKE_C_FLAGS "-std=gnu99")
#add_definitions(-pg)
find_library(SANDGROUSE_LIB NAMES sandgrouse)
add_library(http_parser http_parser.c)
add_executable(rsva11001adapter main.c rsva11001.c)
target_link_libraries(rsva11001adapter http_parser ${SANDGROUSE_LIB})
I run the following to set up the make files:
cmake --debug-output -DCMAKE_BUILD_TYPE=Debug -DCMAKE_PREFIX_PATH="/home/ericu/localdebug" ..
Based on the CMake wiki, setting DCMAKE_PREFIX_PATH does exactly what I want.
CMAKE_PREFIX_PATH
(since CMake 2.6.0) This is used when searching for include files, binaries, or libraries using either the FIND_PACKAGE(), FIND_PATH(), FIND_PROGRAM(), or FIND_LIBRARY() commands. For each path in the CMAKE_PREFIX_PATH list, CMake will check "PATH/include" and "PATH" when FIND_PATH() is called, "PATH/bin" and "PATH" when FIND_PROGRAM() is called, and "PATH/lib" and "PATH" when FIND_LIBRARY() is called. See the documentation for FIND_PACKAGE(), FIND_LIBRARY(), FIND_PATH(), and FIND_PROGRAM() for more details.
However, when I do a 'make VERBOSE=1' this is what I get:
cd /home/ericu/rsva11001adapter/build/src && /usr/bin/gcc -std=gnu99 -g -o CMakeFiles/rsva11001adapter.dir/main.c.o -c /home/ericu/rsva11001adapter/src/main.c
/home/ericu/rsva11001adapter/src/main.c:19:31: fatal error: sandgrouse/server.h: No such file or directory
compilation terminated.
So, it does not seem that CMake is finding things in CMAKE_PREFIX_PATH. It obviously is not adding -I variables to the compiler invocations either.
An inspection of CMakeCache.txt makes it seem as though it has no idea what the variable is:
// No help, variable specified on the command line.
CMAKE_PREFIX_PATH:UNINITIALIZED=/home/ericu/localdebug
I've been working on this for over an hour. I'm nearly at the point of giving up using CMake if it is this difficult to use a non-standard library with it.
You should instruct CMake to add -I flags when compiling your library:
find_path(SANDGROUSE_INCLUDE_DIR sandgrouse/server.h)
include_directories(${SANDGROUSE_INCLUDE_DIR}
Place these lines before add_library() invocation.