In D49466, sys::path::replace_path_prefix was used instead startswith for -f[macro/debug/file]-prefix-map options.
However those were reverted later (commit rG3bb24bf25767ef5bbcef958b484e7a06d8689204) due to broken Windows tests.
This patch restores those replace_path_prefix calls.
It also modifies the prefix matching to be case-insensitive under Windows.
Differential Revision : https://reviews.llvm.org/D76869
http://45.33.8.238/win/3052/step_6.txt
C:\src\llvm-project\clang\test\Preprocessor\file_test.c:9:11: error: CHECK: expected string not found in input
// CHECK: filename: "/UNLIKELY_PATH/empty{{/|\\\\}}file_test.c"
^
<stdin>:1:1: note: scanning from here
^
<stdin>:1:28: note: possible intended match here
^
GCC 8 implements -fmacro-prefix-map. Like -fdebug-prefix-map, it replaces a string prefix for the __FILE__ macro.
-ffile-prefix-map is the union of -fdebug-prefix-map and -fmacro-prefix-map
Reviewed By: rnk, Lekensteyn, maskray
Differential Revision: https://reviews.llvm.org/D49466
Sylvain Audi