[clang] 94a793f - [docs] Improve documentation of -B and --gcc-toolchain

[Fangrui Song via cfe-commits]

Author: Fangrui Song
Date: 2021-03-19T15:42:37-07:00
New Revision: 94a793f096653fa3536f39c6c1b9e3281907619f

URL: https://github.com/llvm/llvm-project/commit/94a793f096653fa3536f39c6c1b9e3281907619f
DIFF: https://github.com/llvm/llvm-project/commit/94a793f096653fa3536f39c6c1b9e3281907619f.diff

LOG: [docs] Improve documentation of -B and --gcc-toolchain

Differential Revision: https://reviews.llvm.org/D97902

Added: 
    

Modified: 
    clang/docs/ClangCommandLineReference.rst
    clang/include/clang/Driver/Options.td

Removed: 
    


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diff  --git a/clang/docs/ClangCommandLineReference.rst b/clang/docs/ClangCommandLineReference.rst
index bca5722f80d0..962d717483e0 100644
--- a/clang/docs/ClangCommandLineReference.rst
+++ b/clang/docs/ClangCommandLineReference.rst
@@ -18,9 +18,9 @@ GCC-compatible ``clang`` and ``clang++`` drivers.
 
 
 .. program:: clang
-.. option:: -B<dir>, --prefix <arg>, --prefix=<arg>
+.. option:: -B<prefix>, --prefix <arg>, --prefix=<arg>
 
-Add <dir> to search path for binaries and object files used implicitly
+Search $prefix/$triple-$file and $prefix$file for executables, libraries, includes, and data files used by the compiler. $prefix may or may not be a directory
 
 .. option:: -F<arg>
 
@@ -256,7 +256,7 @@ Build this module as a system module. Only used with -emit-module
 
 .. option:: --gcc-toolchain=<arg>, -gcc-toolchain <arg>
 
-Use the gcc toolchain at the given directory
+Search for GCC installation in the specified directory on targets which commonly use GCC. The directory usually contains 'lib{,32,64}/gcc{,-cross}/$triple' and 'include'. If specified, sysroot is skipped for GCC detection. Note: executables (e.g. ld) used by the compiler are not overridden by the selected GCC installation
 
 .. option:: -gcodeview
 

diff  --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index b7efb7469a23..85a0e02e6357 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -601,8 +601,14 @@ def _HASH_HASH_HASH : Flag<["-"], "###">, Flags<[NoXarchOption, CoreOption, Flan
 def _DASH_DASH : Option<["--"], "", KIND_REMAINING_ARGS>,
     Flags<[NoXarchOption, CoreOption]>;
 def A : JoinedOrSeparate<["-"], "A">, Flags<[RenderJoined]>, Group<gfortran_Group>;
-def B : JoinedOrSeparate<["-"], "B">, MetaVarName<"<dir>">,
-    HelpText<"Add <dir> to search path for binaries and object files used implicitly">;
+def B : JoinedOrSeparate<["-"], "B">, MetaVarName<"<prefix>">,
+    HelpText<"Search $prefix/$triple-$file and $prefix$file for executables, libraries, "
+    "includes, and data files used by the compiler. $prefix may or may not be a directory">;
+def gcc_toolchain : Joined<["--"], "gcc-toolchain=">, Flags<[NoXarchOption]>,
+  HelpText<"Search for GCC installation in the specified directory on targets which commonly use GCC. "
+  "The directory usually contains 'lib{,32,64}/gcc{,-cross}/$triple' and 'include'. If specified, "
+  "sysroot is skipped for GCC detection. Note: executables (e.g. ld) used by the compiler are not "
+  "overridden by the selected GCC installation">;
 def CC : Flag<["-"], "CC">, Flags<[CC1Option]>, Group<Preprocessor_Group>,
     HelpText<"Include comments from within macros in preprocessed output">,
     MarshallingInfoFlag<PreprocessorOutputOpts<"ShowMacroComments">>;
@@ -3673,8 +3679,6 @@ def print_supported_cpus : Flag<["-", "--"], "print-supported-cpus">,
   MarshallingInfoFlag<FrontendOpts<"PrintSupportedCPUs">>;
 def mcpu_EQ_QUESTION : Flag<["-"], "mcpu=?">, Alias<print_supported_cpus>;
 def mtune_EQ_QUESTION : Flag<["-"], "mtune=?">, Alias<print_supported_cpus>;
-def gcc_toolchain : Joined<["--"], "gcc-toolchain=">, Flags<[NoXarchOption]>,
-  HelpText<"Use the gcc toolchain at the given directory">;
 def time : Flag<["-"], "time">,
   HelpText<"Time individual commands">;
 def traditional_cpp : Flag<["-", "--"], "traditional-cpp">, Flags<[CC1Option]>,