[CMake] Main program not getting rebuilt when library changes.

[Jakub Zakrzewski]

Hi,

if I'm not mistaken, the build system only tracks source dependencies, so unless the changed code is shared by both library and main, it'll not rebuild the main.

One solution could be:

SET_SOURCE_FILES_PROPERTIES(
    cmTestMain.cpp PROPERTIES OBJECT_DEPENDS
    ${CMAKE_CURRENT_BINARY_DIR}/cmTestLib/libcmTestLib.a
)

As described here: http://www.cmake.org/pipermail/cmake/2010-November/041049.html
(I might have used wrongpaths but you get the idea)


--
Gruesse,
Jakub



From: CMake [mailto:cmake-bounces at cmake.org] On Behalf Of Bill Greene
Sent: Freitag, 3. Oktober 2014 01:58
To: Michael Jackson
Cc: cmake at cmake.org
Subject: Re: [CMake] Main program not getting rebuilt when library changes.

I replaced the CMakeLists.txt for the library (cmTestLib) with simply this:

add_library (cmTestLib STATIC MySub.cpp MySub.h)

And I see exactly the same problem with the main program not getting rebuilt.
So I believe the GLOB issue is irrelevant to this particular problem.

Bill

On Thu, Oct 2, 2014 at 6:55 PM, Michael Jackson <mike.jackson at bluequartz.net<mailto:mike.jackson at bluequartz.net>> wrote:
This probably is not completely your issue but I am sure it has something to do with it. From the help for the "FILE" command:

GLOB will generate a list of all files that match the globbing
expressions and store it into the variable.  Globbing expressions are
similar to regular expressions, but much simpler.  If RELATIVE flag is
specified for an expression, the results will be returned as a
relative path to the given path.  (We do not recommend using GLOB to
collect a list of source files from your source tree.  If no
CMakeLists.txt file changes when a source is added or removed then the
generated build system cannot know when to ask CMake to regenerate.)

Take away: Do NOT use GLOB to find source files. List them out one by one in the CMake file.

Try that and let us know if it works as you would expect it to.

Mike Jackson

_________________________________________________________
Mike Jackson                  mike.jackson at bluequartz.net<mailto:mike.jackson at bluequartz.net>
BlueQuartz Software                    www.bluequartz.net<http://www.bluequartz.net>
Principal Software Engineer                  Dayton, Ohio

On Thu, Oct 2, 2014 at 3:38 PM, Bill Greene <w.h.greene at gmail.com<mailto:w.h.greene at gmail.com>> wrote:
Hi,

I'm trying to build a trivial project with cmake 3.0 and Visual Studio 2013.
The project has a top-level directory, a sub-directory with the main program,
and a sub-directory that builds a static library that the main program depends on.
It all builds fine the first time. Then I change a routine in the library and rebuild.
The static library gets rebuilt but the main program does not get re-linked.

I have perused the cmake-built VS project for hours and it looks fine to me; the
main program depends on the library as expected. I can't figure out why the main
program is not being rebuilt.

More embarrassing, I can easily build a similar VS project by hand that behaves as
expected but I can' find the significant difference between the two that is causing the
problematic behavior.

If anyone has any insights on this I would be very appreciative.

Here are my three CMakeLists.txt files:

top level:
-----------
cmake_minimum_required (VERSION 2.8)
project(cmTest)
add_subdirectory (cmTestMain)
add_subdirectory (cmTestLib)

cmTestLib
--------------
FILE(GLOB SRC *.cpp)
FILE(GLOB H_FILES *.h)
add_library (cmTestLib STATIC ${SRC} ${H_FILES})

cmTestMain
----------------
include_directories (${cmTest_SOURCE_DIR}/cmTestLib)
add_executable (cmTestMain cmTestMain.cpp)
target_link_libraries (cmTestMain cmTestLib)

Thanks.

Bill

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