[cfe-dev] clang doesn't find filename from linemarker when compiling preprocessed source

[Taewook Oh via cfe-dev]

Clang appears to always use name as specified on the command line, whereas gcc uses the name as specified in the first linemarker when compiling a preprocessed source. If I use a temporary preprocess file during my build process, the name of the temp file is embedded into the object file. Is this a by-design behavior? Thanks!

Repro:
$ touch test.c
$ gcc -E -o test.i test.c
$ gcc -c -o test.o test.i
$ readelf -a test.o | grep test
1: 0000000000000000 0 FILE LOCAL DEFAULT ABS test.c
$ clang test.c -E -o test.i
$ clang -c -o test.o test.i
$ readelf -a test.o | grep test
1: 0000000000000000 0 FILE LOCAL DEFAULT ABS test.i
$ clang -c -o test.o test.c
$ readelf -a test.o | grep test
1: 0000000000000000 0 FILE LOCAL DEFAULT ABS test.c
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