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POShared libraries and linking on Linux (elf)
 

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    <p>I have read the thread on <a href="https://stackoverflow.com/questions/836875/creating-library-with-backward-compatible-abi-that-uses-boost">Creating Library with backward compatible ABI that uses Boost</a> and I'm now trying to understand how I should link my shared libraries to maintain a stable ABI, and avoid problems with interfering symbols.</p> <p>I have created the following simple test project:</p> <pre><code>cat &lt;&lt;EOF &gt; a.c #define ABI __attribute__((visibility("default"))) int common(); int ABI a() { return common() + 1; } EOF cat &lt;&lt;EOF &gt; b.c #define ABI __attribute__((visibility("default"))) int common(); int ABI b() { return common() + 2; } EOF cat &lt;&lt;EOF &gt; common_v1.c int common() { return 1; } EOF cat &lt;&lt;EOF &gt; common_v2.c int common() { return 2; } EOF cat &lt;&lt;EOF &gt; test.c #include &lt;assert.h&gt; int a(); int b(); int main(int argc, const char *argv[]) { assert( a() + b() == 6 ); return 0; } EOF cat &lt;&lt;EOF &gt; CMakeLists.txt cmake_minimum_required(VERSION 2.8) project(TEST) add_library(common_v1 STATIC common_v1.c) add_library(common_v2 STATIC common_v2.c) SET_SOURCE_FILES_PROPERTIES( a.c b.c COMPILE_FLAGS -fvisibility=hidden ) add_library(a SHARED a.c) target_link_libraries(a common_v1) add_library(b SHARED b.c) target_link_libraries(b common_v2) add_executable(test test.c) target_link_libraries(test a b) EOF </code></pre> <p>The libraries common_v1 and common_v2 should emulate an external dependency of the libraries a and b (like Boost). Because common_v1 and common_v2 is considered as external libraries, I would prefer not to change their build system (and there by not change the flags they are compiled with).</p> <p>The project above, compiles fine, but it does not work! When the test application is executed it jumps into the assert statement.</p> <p>This makes me believe the same definition of common is used in both liba and libb. Why is this the case, and what am I doing wrong?</p>
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