musteresel's blog

Object files with same name in a static library are possible!


tagged: c, c++, cmake

The setup:

# find . -type f

The two name.c files each define a (dummy) function, with different names though!

CMakeLists.txt contains:

cmake_minimum_required(VERSION 3.12)
add_library(foo OBJECT foo/name.c)
add_library(bar OBJECT bar/name.c)
add_library(final STATIC $<TARGET_OBJECTS:foo> $<TARGET_OBJECTS:bar>)

It creates two OBJECT libraries with names foo and bar, and a libfinal.a static library out of the object files of these two.

Inspecting the created libfinal.a shows:

# ar t libfinal.a 

So both object files are in the library. Showing the offset of these files also clearly shows that these are different files:

# ar tO libfinal.a 
name.c.o 0x94
name.c.o 0x570

Linking will search these libraries for the required symbols and just link them if necessary; the names don’t come into play there. Except of course in error messages / debugging output, so it would be really helpful if CMake could add a prefix to the object files somehow … I only found an unanswered post on the mailing list from 2014, though.