r333761 - clang-cl: Expose -no-canonical-prefixes

[Nico Weber via cfe-commits]

Author: nico
Date: Fri Jun  1 07:59:57 2018
New Revision: 333761

URL: http://llvm.org/viewvc/llvm-project?rev=333761&view=rev
Log:
clang-cl: Expose -no-canonical-prefixes

-no-canonical-prefixes is a weird flag: In gcc, it controls whether realpath()
is called on the path of the driver binary. It's needed to support some
usecases where gcc is symlinked to, see
https://gcc.gnu.org/ml/gcc/2011-01/msg00429.html for some background.

In clang, the resource dir is found relative to the compiler binary, and
without -no-canonical-prefixes that's an absolute path. For clang, the main use
case for -no-canonical-prefixes is to make the -resource-dir path added by the
driver relative instead of absolute. Making it relative seems like the better
default, but since neither clang not gcc have -canonical-prefixes without no-
which makes changing the default tricky, and since some symlink behaviors do
depend on the realpath() call at least for gcc, just expose
-no-canonical-prefixes in clang-cl mode.

Alternatively we could default to no-canonical-prefix-mode for clang-cl since
it's less likely to be used in symlinked scenarios, but since you already need
to about -no-canonical-prefixes for the non-clang-cl bits of your build, not
hooking this of driver mode seems better to me.

https://reviews.llvm.org/D47480

Modified:
    cfe/trunk/include/clang/Driver/Options.td
    cfe/trunk/test/Driver/cl-options.c

Modified: cfe/trunk/include/clang/Driver/Options.td
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Driver/Options.td?rev=333761&r1=333760&r2=333761&view=diff
==============================================================================
--- cfe/trunk/include/clang/Driver/Options.td (original)
+++ cfe/trunk/include/clang/Driver/Options.td Fri Jun  1 07:59:57 2018
@@ -2261,7 +2261,7 @@ def multi__module : Flag<["-"], "multi_m
 def multiply__defined__unused : Separate<["-"], "multiply_defined_unused">;
 def multiply__defined : Separate<["-"], "multiply_defined">;
 def mwarn_nonportable_cfstrings : Flag<["-"], "mwarn-nonportable-cfstrings">, Group<m_Group>;
-def no_canonical_prefixes : Flag<["-"], "no-canonical-prefixes">, Flags<[HelpHidden]>,
+def no_canonical_prefixes : Flag<["-"], "no-canonical-prefixes">, Flags<[HelpHidden, CoreOption]>,
   HelpText<"Use relative instead of canonical paths">;
 def no_cpp_precomp : Flag<["-"], "no-cpp-precomp">, Group<clang_ignored_f_Group>;
 def no_integrated_cpp : Flag<["-", "--"], "no-integrated-cpp">, Flags<[DriverOption]>;

Modified: cfe/trunk/test/Driver/cl-options.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Driver/cl-options.c?rev=333761&r1=333760&r2=333761&view=diff
==============================================================================
--- cfe/trunk/test/Driver/cl-options.c (original)
+++ cfe/trunk/test/Driver/cl-options.c Fri Jun  1 07:59:57 2018
@@ -591,6 +591,8 @@
 // RUN:     -flimit-debug-info \
 // RUN:     -flto \
 // RUN:     -fmerge-all-constants \
+// RUN:     -no-canonical-prefixes \
+// RUN:     -fno-coverage-mapping \
 // RUN:     --version \
 // RUN:     -Werror /Zs -- %s 2>&1