Revert "[Driver] Use -fuse-line-directives by default in MSVC mode"

This reverts commit SVN r331666.

It was afterwards pointed out in https://reviews.llvm.org/D46520
that #line directives lose information about what parts come from a
system header. That means the result of -E usually won't compile,
since Windows headers are typically full of warnings and
default-error warnings.

llvm-svn: 331858

clang/lib/Driver/ToolChains/Clang.cpp

@@ -4224,9 +4224,9 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
                    IsWindowsMSVC))
     CmdArgs.push_back("-fms-extensions");
 
-  // -fno-use-line-directives is default, except for MSVC targets.
+  // -fno-use-line-directives is default.
   if (Args.hasFlag(options::OPT_fuse_line_directives,
-                   options::OPT_fno_use_line_directives, IsWindowsMSVC))
+                   options::OPT_fno_use_line_directives, false))
     CmdArgs.push_back("-fuse-line-directives");
 
   // -fms-compatibility=0 is default.

clang/test/Driver/cl-options.c

@@ -28,7 +28,6 @@
 
 // RUN: %clang_cl /E -### -- %s 2>&1 | FileCheck -check-prefix=E %s
 // E: "-E"
-// E: "-fuse-line-directives"
 // E: "-o" "-"
 
 // RUN: %clang_cl /EP -### -- %s 2>&1 | FileCheck -check-prefix=EP %s