[CMake] Problem with cmake cross-compiling - make complains of missing header.

Eric Noulard

2011-11-09 19:00:40 UTC

Post by Thomas Walwyn
Hi All,
I’m brand-new to cmake, and have run into a problem cross compiling for an
Make complains about missing file 'curl/curl.h' when compiling against an
Intel SDK for linux. 'curl/curl.h' resides in the cross-compile toolchain
under [toolchain-folder]/include/curl/curl.h. The toolchain file
'toolchain.cmake' resides at the root of the SDK (toolchain.cmake attached
to end).
The build is configured with the usual 'cmake
-DCMAKE_TOOLCHAIN_FILE=[path-to-toolchain] ..' from a 'build' folder in the
src directory of my application tree. cmake finds the compiler toolchain
(gcc, gxx, ar, etc.) and completes the configuration all good (cmake output
attached to end). The problem comes in when make is called. The strange
thing is, the variable 'CURL_HEADER' contains the path of curl/curl.h if the
FIND_FILE(
        CURL_HEADER
        curl/curl.h
        ONLY_CMAKE_FIND_ROOT_PATH
                )

finding the file is not enough.
You then need to add corresponding path to the include directory list.
Something like:

find_path(CURL_INCLUDE_DIR
NAMES curl.h
ONLY_CMAKE_FIND_ROOT_PATH)

include_directories(${CURL_INCLUDE_DIR})
should do it.

or may be

include_directories(${CURL_INCLUDE_DIR}/..) <-- parent dir

because you use #include "curl/curl.h" in your prog and not #include "curl.h"

Post by Thomas Walwyn
This means that cmake can 'see' the file that make is complaining about. My
question is why, if cmake can see the file, does make complain that it
cannot find the file?

Because CMakeLists.txt did not teach the **compiler** how to use/find it.

Post by Thomas Walwyn
Something must be missing with the configuration of
the cross-compilation.
For reference, the program compiles perfectly on the host system, without
the -DCMAKE_TOOLCHAIN_FILE flag. The host system is Fedora 13 with curl and
its headers installed.

probably because curl/curl.h is in a standard location like
/usr/include/curl/curl.h which is on the default include path.

Post by Thomas Walwyn
I've also attached the important bits of the make output to the end for reference.
Any help is greatly appreciated.
Many thanks and kind regards,
Thomas Walwyn
#------------------------toolchain.cmake----------------------------------#
SET(CMAKE_SYSTEM_NAME Linux)
SET(CMAKE_SYSTEM_VERSION 1)
SET(CMAKE_C_COMPILER [path-to-compiler]/[platform]-linux-gcc)
SET(CMAKE_FIND_ROOT_PATH [path-to-toolchain-folder])
SET(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
SET(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
SET(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
#------------------------cmake output----------------------------------#
-- The C compiler identification is GNU
-- The CXX compiler identification is GNU
-- Check for working C compiler: [path-to-compiler]/[platform]-linux-gcc
-- Check for working C compiler: [path-to-compiler]/[platform]-linux-gcc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working CXX compiler: [path-to-compiler]/[platform]-linux-c++
-- Check for working CXX compiler: [path-to-compiler]/[platform]-linux-c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Configuring done
-- Generating done
-- Build files have been written to: [path-to-application-folder]/build
#-----------------------part of make which gives error------------------#
cd [path-to-application-source] && [path-to-compiler]/[platform]-linux-gcc
-DIPFrontend_EXPORTS -fPIC -I[path-to-application-source]/includes -o
[path-to-application-source]/[source-file].c.o -c
[path-to-application-source]/[source-file]/[path-to-application-source]/[source-file].c
[path-to-application-source]/[source-file].c:50:23: error: curl/curl.h: No
such file or directory
--
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Erk
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