[CMake] Problems with auto-generated sources

[Williams, Norman K]

I don't see the problem you're having.

I re-wrote your CMakeLists.txt slightly to not use Unix commands:

========================================================================
cmake_minimum_required(VERSION 2.8)
project(Test)

add_custom_command(OUTPUT file.c
    COMMAND echo "GENERATING FILE"
    COMMAND ${CMAKE_COMMAND} -E remove file.c
    COMMAND ${CMAKE_COMMAND} -E copy ${CMAKE_CURRENT_SOURCE_DIR}/org.c
file.c
    DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/org.c
  )
add_library(LibFile file.c)

add_executable(test1 test.c)
target_link_libraries(test1 LibFile)

add_executable(test2 test.c)
target_link_libraries(test2 LibFile)


========================================================================

I only see GENERATING FILE once, even after the touch command.

Could you be using an old version of CMake? I tested with the current
development head, i.e. post-2.8.11.2


developer 116% cmake ../src
-- The C compiler identification is Clang 4.2.0
-- The CXX compiler identification is Clang 4.2.0
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Configuring done
-- Generating done
-- Build files have been written to: /scratch/kent/cmake/test/build
developer 117% make
[ 25%] Generating file.c
GENERATING FILE
Scanning dependencies of target LibFile
[ 50%] Building C object CMakeFiles/LibFile.dir/file.c.o
Linking C static library libLibFile.a
/usr/bin/ranlib: file: libLibFile.a(file.c.o) has no symbols
/usr/bin/ranlib: file: libLibFile.a(file.c.o) has no symbols
/usr/bin/ranlib: warning for library: libLibFile.a the table of contents
is empty (no object file members in the library define global symbols)
[ 50%] Built target LibFile
Scanning dependencies of target test1
[ 75%] Building C object CMakeFiles/test1.dir/test.c.o
Linking C executable test1
[ 75%] Built target test1
Scanning dependencies of target test2
[100%] Building C object CMakeFiles/test2.dir/test.c.o
Linking C executable test2
[100%] Built target test2
developer 123% touch ../src/org.c
developer 124% make
[ 25%] Generating file.c
GENERATING FILE
Scanning dependencies of target LibFile
[ 50%] Building C object CMakeFiles/LibFile.dir/file.c.o
Linking C static library libLibFile.a
/usr/bin/ranlib: file: libLibFile.a(file.c.o) has no symbols
/usr/bin/ranlib: file: libLibFile.a(file.c.o) has no symbols
/usr/bin/ranlib: warning for library: libLibFile.a the table of contents
is empty (no object file members in the library define global symbols)
[ 50%] Built target LibFile
Linking C executable test1
[ 75%] Built target test1
Linking C executable test2
[100%] Built target test2





--
Kent Williams norman-k-williams at uiowa.edu



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