[flang][driver] Mark -Wl as visible in Flang

[kiranchandramohan]

LG.

clang/include/clang/Driver/Options.td

def Wsystem_headers_in_module_EQ : Joined<["-"], "Wsystem-headers-in-module=">,
   MetaVarName<"<module>">,
   HelpText<"Enable -Wsystem-headers when building <module>">,
   MarshallingInfoStringVector<DiagnosticOpts<"SystemHeaderWarningsModules">>;
 def Wdeprecated : Flag<["-"], "Wdeprecated">, Group<W_Group>,
   Visibility<[ClangOption, CC1Option]>,
   HelpText<"Enable warnings for deprecated constructs and define __DEPRECATED">;
 def Wno_deprecated : Flag<["-"], "Wno-deprecated">, Group<W_Group>,
   Visibility<[ClangOption, CC1Option]>;
-def Wl_COMMA : CommaJoined<["-"], "Wl,">, Flags<[LinkerInput, RenderAsInput]>,
+def Wl_COMMA : CommaJoined<["-"], "Wl,">, Visibility<[ClangOption, FlangOption]>,
+  Flags<[LinkerInput, RenderAsInput]>,
   HelpText<"Pass the comma separated arguments in <arg> to the linker">,
   MetaVarName<"<arg>">, Group<Link_Group>;
 // FIXME: This is broken; these should not be Joined arguments.
 def Wno_nonportable_cfstrings : Joined<["-"], "Wno-nonportable-cfstrings">, Group<W_Group>,
   Visibility<[ClangOption, CC1Option]>;
 def Wnonportable_cfstrings : Joined<["-"], "Wnonportable-cfstrings">, Group<W_Group>,
   Visibility<[ClangOption, CC1Option]>;
 def Wp_COMMA : CommaJoined<["-"], "Wp,">,

flang/test/Driver/driver-help-hidden.f90

 ! CHECK-NEXT: -save-temps=<value>     Save intermediate compilation results.
 ! CHECK-NEXT: -save-temps             Save intermediate compilation results
 ! CHECK-NEXT: -std=<value>            Language standard to compile for
 ! CHECK-NEXT: -S                      Only run preprocess and compilation steps
 ! CHECK-NEXT: --target=<value>        Generate code for the given target
 ! CHECK-NEXT: -U <macro>              Undefine macro <macro>
 ! CHECK-NEXT: --version               Print version information
 ! CHECK-NEXT: -v                      Show commands to run and use verbose output
+! CHECK-NEXT: -Wl,<arg>               Pass the comma separated arguments in <arg> to the linker
 ! CHECK-NEXT: -W<warning>             Enable the specified warning
 ! CHECK-NEXT: -Xflang <arg>           Pass <arg> to the flang compiler
 ! CHECK-NEXT: -x <language>           Treat subsequent input files as having type <language>
 
 
 ! ERROR-FLANG: error: unknown argument '-help-hidden'; did you mean '--help-hidden'?
 
 ! Frontend driver -help-hidden is not supported
 ! ERROR-FLANG-FC1: error: unknown argument: '{{.*}}'

flang/test/Driver/driver-help.f90

 ! HELP-NEXT: -save-temps=<value>     Save intermediate compilation results.
 ! HELP-NEXT: -save-temps             Save intermediate compilation results
 ! HELP-NEXT: -std=<value>            Language standard to compile for
 ! HELP-NEXT: -S                      Only run preprocess and compilation steps
 ! HELP-NEXT: --target=<value>        Generate code for the given target
 ! HELP-NEXT: -U <macro>              Undefine macro <macro>
 ! HELP-NEXT: --version               Print version information
 ! HELP-NEXT: -v                      Show commands to run and use verbose output
+! HELP-NEXT: -Wl,<arg>               Pass the comma separated arguments in <arg> to the linker
 ! HELP-NEXT: -W<warning>             Enable the specified warning
 ! HELP-NEXT: -Xflang <arg>           Pass <arg> to the flang compiler
 ! HELP-NEXT: -x <language>           Treat subsequent input files as having type <language>
 
 
 ! HELP-FC1:USAGE: flang
 ! HELP-FC1-EMPTY:
 ! HELP-FC1-NEXT:OPTIONS:

flang/test/Driver/misc-flags.f90

 ! Make sure that `-l` is "visible" to Flang's driver
 ! RUN: %flang -lpgmath -### %s
 
+! Make sure that `-Wl` is "visible" to Flang's driver
+! RUN: %flang -Wl,abs -### %s
+
 program hello
   write(*,*), "Hello world!"
 end program hello