Bug 16185 – Contents of object files are non-deterministic

When compiling an object file, the output should be deterministic. That is, if no source has changed, DMD should generate a bit-for-bit identical object file. This simple property is very useful for build systems that cache outputs. Here is a simple test case: // test.d void main() { } $ dmd -c test.d; md5sum test.o 06b67b4d208f584dc694c19a52a924e6 $ dmd -c test.d; md5sum test.o 3445450e1f08f0f026950eeac3379b65 Note that this does not happen if the object was compiled on the same clock second. Thus, if run twice in quick succession, the contents will be the same (it may require a few tries): $ dmd -c test.d; md5sum test.o; dmd -c test.d; md5sum test.o 3445450e1f08f0f026950eeac3379b65 test.o 3445450e1f08f0f026950eeac3379b65 test.o If compiling directly to an executable, the output is deterministic: $ dmd test.d; md5sum test 1d4b786c39156f41b5c1f505940f8936 test $ dmd test.d; md5sum test 1d4b786c39156f41b5c1f505940f8936 test I have only tested this on Linux x86_64, but it seems likely that the problem exists on other architectures and platforms as well.

Duplicate of #14976 *** This issue has been marked as a duplicate of issue 14976 ***