Print out "Alias for -foo" instead of repeating the same help message for -foo.

Since aliases don't actually need name, I removed it from Options.td
to keep the definitions concise.

Before:

  -(                      Ignored for compatibility with GNU unless you pass --warn-backrefs
  -)                      Ignored for compatibility with GNU unless you pass --warn-backrefs
  --allow-multiple-definition Allow multiple definitions
  --apply-dynamic-relocs  Apply dynamic relocations to place
  --as-needed             Only set DT_NEEDED for shared libraries if used
  --auxiliary=<value>     Set DT_AUXILIARY field to the specified name
  --Bdynamic              Link against shared libraries
  --Bshareable            Build a shared object
  ...

After:

  -(                      Alias for --start-group
  -)                      Alias for --end-group
  --allow-multiple-definition Allow multiple definitions
  --apply-dynamic-relocs  Apply dynamic relocations to place
  --as-needed             Only set DT_NEEDED for shared libraries if used
  --auxiliary=<value>     Set DT_AUXILIARY field to the specified name
  --Bdynamic              Link against shared libraries (default)
  --Bshareable            Alias for --shared
  ...

Differential Revision: https://reviews.llvm.org/D47588

llvm-svn: 333694

Author: rui314

lld/ELF/Options.td

@@ -352,45 +352,45 @@ def z: JoinedOrSeparate<["-"], "z">, MetaVarName<"<option>">,
   HelpText<"Linker option extensions">;
 
 // Aliases
-def alias_auxiliary: Separate<["-"], "f">, Alias<auxiliary>;
-def alias_Bdynamic_call_shared: F<"call_shared">, Alias<Bdynamic>;
-def alias_Bdynamic_dy: F<"dy">, Alias<Bdynamic>;
-def alias_Bstatic_dn: F<"dn">, Alias<Bstatic>;
-def alias_Bstatic_non_shared: F<"non_shared">, Alias<Bstatic>;
-def alias_Bstatic_static: F<"static">, Alias<Bstatic>;
-def alias_define_common_d: Flag<["-"], "d">, Alias<define_common>;
-def alias_define_common_dc: F<"dc">, Alias<define_common>;
-def alias_define_common_dp: F<"dp">, Alias<define_common>;
-def alias_discard_all_x: Flag<["-"], "x">, Alias<discard_all>;
-def alias_discard_locals_X: Flag<["-"], "X">, Alias<discard_locals>;
-def alias_emit_relocs: Flag<["-"], "q">, Alias<emit_relocs>;
-def alias_end_group_paren: Flag<["-"], ")">, Alias<end_group>;
-def alias_entry_e: JoinedOrSeparate<["-"], "e">, Alias<entry>;
-def alias_export_dynamic_E: Flag<["-"], "E">, Alias<export_dynamic>;
-def alias_filter: Separate<["-"], "F">, Alias<filter>;
-def alias_format_b: Separate<["-"], "b">, Alias<format>;
-def alias_library: JoinedOrSeparate<["-"], "l">, Alias<library>;
-def alias_library_path: JoinedOrSeparate<["-"], "L">, Alias<library_path>;
-def alias_no_pie_pic_executable: F<"no-pic-executable">, Alias<no_pie>;
-def alias_omagic: Flag<["-"], "N">, Alias<omagic>;
-def alias_o_output: Joined<["--"], "output=">, Alias<o>;
-def alias_o_output2 : Separate<["--"], "output">, Alias<o>;
-def alias_pie_pic_executable: F<"pic-executable">, Alias<pie>;
-def alias_print_map_M: Flag<["-"], "M">, Alias<print_map>;
-def alias_relocatable_r: Flag<["-"], "r">, Alias<relocatable>;
-def alias_rpath_R: JoinedOrSeparate<["-"], "R">, Alias<rpath>;
-def alias_script_T: JoinedOrSeparate<["-"], "T">, Alias<script>;
-def alias_shared_Bshareable: F<"Bshareable">, Alias<shared>;
-def alias_soname_h: JoinedOrSeparate<["-"], "h">, Alias<soname>;
-def alias_start_group_paren: Flag<["-"], "(">, Alias<start_group>;
-def alias_strip_all: Flag<["-"], "s">, Alias<strip_all>;
-def alias_strip_debug_S: Flag<["-"], "S">, Alias<strip_debug>;
-def alias_trace: Flag<["-"], "t">, Alias<trace>;
-def alias_trace_symbol_y : JoinedOrSeparate<["-"], "y">, Alias<trace_symbol>;
-def alias_Ttext_segment: Separate<["-", "--"], "Ttext-segment">, Alias<Ttext>;
-def alias_Ttext_segment_eq: Joined<["-", "--"], "Ttext-segment=">, Alias<Ttext>;
-def alias_undefined_u: JoinedOrSeparate<["-"], "u">, Alias<undefined>;
-def alias_version_V: Flag<["-"], "V">, Alias<version>;
+def: Separate<["-"], "f">, Alias<auxiliary>, HelpText<"Alias for --auxiliary">;
+def: F<"call_shared">, Alias<Bdynamic>, HelpText<"Alias for --Bdynamic">;
+def: F<"dy">, Alias<Bdynamic>, HelpText<"Alias for --Bdynamic">;
+def: F<"dn">, Alias<Bstatic>, HelpText<"Alias for --Bstatic">;
+def: F<"non_shared">, Alias<Bstatic>, HelpText<"Alias for --Bstatic">;
+def: F<"static">, Alias<Bstatic>, HelpText<"Alias for --Bstatic">;
+def: Flag<["-"], "d">, Alias<define_common>, HelpText<"Alias for --define-common">;
+def: F<"dc">, Alias<define_common>, HelpText<"Alias for --define-common">;
+def: F<"dp">, Alias<define_common>, HelpText<"Alias for --define-common">;
+def: Flag<["-"], "x">, Alias<discard_all>, HelpText<"Alias for --discard-all">;
+def: Flag<["-"], "X">, Alias<discard_locals>, HelpText<"Alias for --discard-locals">;
+def: Flag<["-"], "q">, Alias<emit_relocs>, HelpText<"Alias for --emit-relocs">;
+def: Flag<["-"], ")">, Alias<end_group>, HelpText<"Alias for --end-group">;
+def: JoinedOrSeparate<["-"], "e">, Alias<entry>, HelpText<"Alias for --entry">;
+def: Flag<["-"], "E">, Alias<export_dynamic>, HelpText<"Alias for --export-dynamic">;
+def: Separate<["-"], "F">, Alias<filter>, HelpText<"Alias for --filter">;
+def: Separate<["-"], "b">, Alias<format>, HelpText<"Alias for --format">;
+def: JoinedOrSeparate<["-"], "l">, Alias<library>, HelpText<"Alias for --library">;
+def: JoinedOrSeparate<["-"], "L">, Alias<library_path>, HelpText<"Alias for --library-path">;
+def: F<"no-pic-executable">, Alias<no_pie>, HelpText<"Alias for --no-pie">;
+def: Flag<["-"], "N">, Alias<omagic>, HelpText<"Alias for --omagic">;
+def: Joined<["--"], "output=">, Alias<o>, HelpText<"Alias for -o">;
+def: Separate<["--"], "output">, Alias<o>, HelpText<"Alias for -o">;
+def: F<"pic-executable">, Alias<pie>, HelpText<"Alias for --pie">;
+def: Flag<["-"], "M">, Alias<print_map>, HelpText<"Alias for --print-map">;
+def: Flag<["-"], "r">, Alias<relocatable>, HelpText<"Alias for --relocatable">;
+def: JoinedOrSeparate<["-"], "R">, Alias<rpath>, HelpText<"Alias for --rpath">;
+def: JoinedOrSeparate<["-"], "T">, Alias<script>, HelpText<"Alias for --script">;
+def: F<"Bshareable">, Alias<shared>, HelpText<"Alias for --shared">;
+def: JoinedOrSeparate<["-"], "h">, Alias<soname>, HelpText<"Alias for --soname">;
+def: Flag<["-"], "(">, Alias<start_group>, HelpText<"Alias for --start-group">;
+def: Flag<["-"], "s">, Alias<strip_all>, HelpText<"Alias for --strip-all">;
+def: Flag<["-"], "S">, Alias<strip_debug>, HelpText<"Alias for --strip-debug">;
+def: Flag<["-"], "t">, Alias<trace>, HelpText<"Alias for --trace">;
+def: JoinedOrSeparate<["-"], "y">, Alias<trace_symbol>, HelpText<"Alias for --trace-symbol">;
+def: Separate<["-", "--"], "Ttext-segment">, Alias<Ttext>, HelpText<"Alias for --Ttext">;
+def: Joined<["-", "--"], "Ttext-segment=">, Alias<Ttext>, HelpText<"Alias for --Ttext">;
+def: JoinedOrSeparate<["-"], "u">, Alias<undefined>, HelpText<"Alias for --undefined">;
+def: Flag<["-"], "V">, Alias<version>, HelpText<"Alias for --version">;
 
 // LTO-related options.
 def lto_aa_pipeline: J<"lto-aa-pipeline=">,
@@ -420,16 +420,19 @@ def thinlto_cache_dir: J<"thinlto-cache-dir=">,
 defm thinlto_cache_policy: Eq<"thinlto-cache-policy", "Pruning policy for the ThinLTO cache">;
 def thinlto_jobs: J<"thinlto-jobs=">, HelpText<"Number of ThinLTO jobs">;
 
-def plugin_opt_O: J<"plugin-opt=O">, Alias<lto_O>;
-def plugin_opt_debug_pass_manager: F<"plugin-opt=debug-pass-manager">, Alias<lto_debug_pass_manager>;
-def plugin_opt_disable_verify: F<"plugin-opt=disable-verify">, Alias<disable_verify>;
-def plugin_opt_jobs_eq: J<"plugin-opt=jobs=">, Alias<thinlto_jobs>;
-def plugin_opt_lto_partitions_eq: J<"plugin-opt=lto-partitions=">, Alias<lto_partitions>;
+def: J<"plugin-opt=O">, Alias<lto_O>, HelpText<"Alias for -lto-O">;
+def: F<"plugin-opt=debug-pass-manager">,
+  Alias<lto_debug_pass_manager>, HelpText<"Alias for -lto-debug-pass-manager">;
+def: F<"plugin-opt=disable-verify">, Alias<disable_verify>, HelpText<"Alias for -disable-verify">;
+def: J<"plugin-opt=jobs=">, Alias<thinlto_jobs>, HelpText<"Alias for -thinlto-jobs">;
+def: J<"plugin-opt=lto-partitions=">, Alias<lto_partitions>, HelpText<"Alias for -lto-partitions">;
 def plugin_opt_mcpu_eq: J<"plugin-opt=mcpu=">;
-def plugin_opt_new_pass_manager: F<"plugin-opt=new-pass-manager">, Alias<lto_new_pass_manager>;
+def: F<"plugin-opt=new-pass-manager">,
+  Alias<lto_new_pass_manager>, HelpText<"Alias for -lto-new-pass-manager">;
 def plugin_opt_obj_path_eq: J<"plugin-opt=obj-path=">;
-def plugin_opt_sample_profile_eq: J<"plugin-opt=sample-profile=">, Alias<lto_sample_profile>;
-def plugin_opt_save_temps: F<"plugin-opt=save-temps">, Alias<save_temps>;
+def: J<"plugin-opt=sample-profile=">,
+  Alias<lto_sample_profile>, HelpText<"Alias for -lto-sample-profile">;
+def: F<"plugin-opt=save-temps">, Alias<save_temps>, HelpText<"Alias for -save-temps">;
 def plugin_opt_thinlto_emit_imports_files: F<"plugin-opt=thinlto-emit-imports-files">;
 def plugin_opt_thinlto_index_only: F<"plugin-opt=thinlto-index-only">;
 def plugin_opt_thinlto_index_only_eq: J<"plugin-opt=thinlto-index-only=">;

lld/test/ELF/help.s

@@ -1,5 +1,5 @@
 # RUN: ld.lld --help 2>&1 | FileCheck %s
 # CHECK:  OPTIONS:
-# CHECK:  --output=<value>        Path to file to write output
-# CHECK:  --output <value>        Path to file to write output
+# CHECK:  --output=<value>        Alias for -o
+# CHECK:  --output <value>        Alias for -o
 # CHECK:  -o <path>               Path to file to write output