Add "(default)" to default options

[ruiu]

Summary

This improves the help message shown for ld.lld --help.

[pcc]

LGTM

[jhenderson]

Hi @ruiu,

I was just looking at this change, and I noticed one slight mistake in this: the --discard-none switch is not the default behaviour of LLD. If it were, the default DiscardPolicy would be DiscardPolicy::None, when in fact it is DiscardPolicy::Default and there's a difference in the behaviour between the two in shouldKeepInSymtab.

[ruiu]

Oh, thank you for finding that mistake! I'll just remove "(default)" from that option.

lld/ELF/Options.td

 
 defm auxiliary: Eq<"auxiliary", "Set DT_AUXILIARY field to the specified name">;
 
 def Bsymbolic: F<"Bsymbolic">, HelpText<"Bind defined symbols locally">;
 
 def Bsymbolic_functions: F<"Bsymbolic-functions">,
   HelpText<"Bind defined function symbols locally">;
 
-def Bdynamic: F<"Bdynamic">, HelpText<"Link against shared libraries">;
+def Bdynamic: F<"Bdynamic">, HelpText<"Link against shared libraries (default)">;
 
 def Bstatic: F<"Bstatic">, HelpText<"Do not link against shared libraries">;
 
 def build_id: F<"build-id">, HelpText<"Generate build ID note">;
 
 def build_id_eq: J<"build-id=">, HelpText<"Generate build ID note">;
 
 defm check_sections : B<"check-sections",
-    "Check section addresses for overlaps",
+    "Check section addresses for overlaps (default)",
     "Do not check section addresses for overlaps">;
 
 defm compress_debug_sections:
   Eq<"compress-debug-sections", "Compress DWARF debug sections">;
 
 defm defsym: Eq<"defsym", "Define a symbol alias">;
 
 defm library_path:
   Eq<"library-path", "Add a directory to the library search path">, MetaVarName<"<dir>">;
 
 def O: JoinedOrSeparate<["-"], "O">, HelpText<"Optimize output file size">;
 
 defm Tbss: Eq<"Tbss", "Same as --section-start with .bss as the sectionname">;
 
 defm Tdata: Eq<"Tdata", "Same as --section-start with .data as the sectionname">;
 
 defm Ttext: Eq<"Ttext", "Same as --section-start with .text as the sectionname">;
 
 defm allow_multiple_definition: B<"allow-multiple-definition",
     "Allow multiple definitions",
-    "Do not allow multiple definitions">;
+    "Do not allow multiple definitions (default)">;
 
 defm apply_dynamic_relocs: B<"apply-dynamic-relocs",
     "Apply dynamic relocations to place",
     "Do not apply dynamic relocations to place">;
 
 defm as_needed: B<"as-needed",
     "Only set DT_NEEDED for shared libraries if used",
-    "Always set DT_NEEDED for shared libraries">;
+    "Always set DT_NEEDED for shared libraries (default)">;
 
 defm call_graph_ordering_file:
   Eq<"call-graph-ordering-file", "Layout sections to optimize the given callgraph">;
 
 // -chroot doesn't have a help text because it is an internal option.
 def chroot: Separate<["--", "-"], "chroot">;
 
 def color_diagnostics: F<"color-diagnostics">,
   HelpText<"Use colors in diagnostics">;
 
 def color_diagnostics_eq: J<"color-diagnostics=">,
   HelpText<"Use colors in diagnostics; one of 'always', 'never', 'auto'">;
 
 defm cref: B<"cref",
     "Output cross reference table",
     "Do not output cross reference table">;
 
 defm define_common: B<"define-common",
     "Assign space to common symbols",
     "Do not assign space to common symbols">;
 
 defm demangle: B<"demangle",
-    "Demangle symbol names",
+    "Demangle symbol names (default)",
     "Do not demangle symbol names">;
 
 def disable_new_dtags: F<"disable-new-dtags">,
   HelpText<"Disable new dynamic tags">;
 
 def discard_all: F<"discard-all">, HelpText<"Delete all local symbols">;
 
 def discard_locals: F<"discard-locals">,
   HelpText<"Delete temporary local symbols">;
 
 def discard_none: F<"discard-none">,
-  HelpText<"Keep all symbols in the symbol table">;
+  HelpText<"Keep all symbols in the symbol table (default)">;
 
 defm dynamic_linker: Eq<"dynamic-linker", "Which dynamic linker to use">;
 
 defm dynamic_list: Eq<"dynamic-list", "Read a list of dynamic symbols">;
 
 defm eh_frame_hdr: B<"eh-frame-hdr",
     "Request creation of .eh_frame_hdr section and PT_GNU_EH_FRAME segment header",
     "Do not create .eh_frame_hdr section">;
 
 def emit_relocs: F<"emit-relocs">, HelpText<"Generate relocations in output">;
 
 def enable_new_dtags: F<"enable-new-dtags">,
-  HelpText<"Enable new dynamic tags">;
+  HelpText<"Enable new dynamic tags (default)">;
 
 def end_group: F<"end-group">,
   HelpText<"Ignored for compatibility with GNU unless you pass --warn-backrefs">;
 
 def end_lib: F<"end-lib">,
   HelpText<"End a grouping of objects that should be treated as if they were together in an archive">;
 
 defm entry: Eq<"entry", "Name of entry point symbol">,
   MetaVarName<"<entry>">;
 
 defm error_limit:
   Eq<"error-limit", "Maximum number of errors to emit before stopping (0 = no limit)">;
 
 def error_unresolved_symbols: F<"error-unresolved-symbols">,
   HelpText<"Report unresolved symbols as errors">;
 
 defm exclude_libs: Eq<"exclude-libs", "Exclude static libraries from automatic export">;
 
 defm export_dynamic: B<"export-dynamic",
     "Put symbols in the dynamic symbol table",
-    "Do not put symbols in the dynamic symbol table">;
+    "Do not put symbols in the dynamic symbol table (default)">;
 
 defm export_dynamic_symbol:
   Eq<"export-dynamic-symbol", "Put a symbol in the dynamic symbol table">;
 
 defm fatal_warnings: B<"fatal-warnings",
     "Treat warnings as errors",
-    "Do not treat warnings as errors">;
+    "Do not treat warnings as errors (default)">;
 
 defm filter: Eq<"filter", "Set DT_FILTER field to the specified name">;
 
 defm fini: Eq<"fini", "Specify a finalizer function">, MetaVarName<"<symbol>">;
 
 def fix_cortex_a53_843419: F<"fix-cortex-a53-843419">,
   HelpText<"Apply fixes for AArch64 Cortex-A53 erratum 843419">;
 
 defm format: Eq<"format", "Change the input format of the inputs following this option">,
   MetaVarName<"<input-format>">;
 
 defm gc_sections: B<"gc-sections",
     "Enable garbage collection of unused sections",
-    "Disable garbage collection of unused sections">;
+    "Disable garbage collection of unused sections (default)">;
 
 defm gdb_index: B<"gdb-index",
     "Generate .gdb_index section",
-    "Do not generate .gdb_index section">;
+    "Do not generate .gdb_index section (default)">;
 
 defm gnu_unique: B<"gnu-unique",
-  "Enable STB_GNU_UNIQUE symbol binding",
+  "Enable STB_GNU_UNIQUE symbol binding (default)",
   "Disable STB_GNU_UNIQUE symbol binding">;
 
 defm hash_style: Eq<"hash-style", "Specify hash style (sysv, gnu or both)">;
 
 def help: F<"help">, HelpText<"Print option help">;
 
 def icf_all: F<"icf=all">, HelpText<"Enable identical code folding">;
 
-def icf_none: F<"icf=none">, HelpText<"Disable identical code folding">;
+def icf_none: F<"icf=none">, HelpText<"Disable identical code folding (default)">;
 
 def ignore_function_address_equality: F<"ignore-function-address-equality">,
   HelpText<"lld can break the address equality of functions">;
 
 def ignore_data_address_equality: F<"ignore-data-address-equality">,
   HelpText<"lld can break the address equality of data">;
 
 defm image_base: Eq<"image-base", "Set the base address">;
 
 defm init: Eq<"init", "Specify an initializer function">,
   MetaVarName<"<symbol>">;
 
 defm just_symbols: Eq<"just-symbols", "Just link symbols">;
 
 defm keep_unique: Eq<"keep-unique", "Do not fold this symbol during ICF">;
 
 defm library: Eq<"library", "Root name of library to use">,
   MetaVarName<"<libName>">;
 
 def m: JoinedOrSeparate<["-"], "m">, HelpText<"Set target emulation">;
 
 defm Map: Eq<"Map", "Print a link map to the specified file">;
 
 defm merge_exidx_entries: B<"merge-exidx-entries",
-    "Enable merging .ARM.exidx entries",
+    "Enable merging .ARM.exidx entries (default)",
     "Disable merging .ARM.exidx entries">;
 
 def nostdlib: F<"nostdlib">,
   HelpText<"Only search directories specified on the command line">;
 
 def no_color_diagnostics: F<"no-color-diagnostics">,
   HelpText<"Do not use colors in diagnostics">;
 
defm orphan_handling:
   Eq<"orphan-handling", "Control how orphan sections are handled when linker script used">;
 
 defm pack_dyn_relocs:
   Eq<"pack-dyn-relocs", "Pack dynamic relocations in the given format (none or android)">,
   MetaVarName<"<format>">;
 
 defm pie: B<"pie",
     "Create a position independent executable",
-    "Do not create a position independent executable">;
+    "Do not create a position independent executable (default)">;
 
 defm print_gc_sections: B<"print-gc-sections",
     "List removed unused sections",
-    "Do not list removed unused sections">;
+    "Do not list removed unused sections (default)">;
 
 defm print_icf_sections: B<"print-icf-sections",
     "List identical folded sections",
-    "Do not list identical folded sections">;
+    "Do not list identical folded sections (default)">;
 
 def print_map: F<"print-map">,
   HelpText<"Print a link map to the standard output">;
 
 defm reproduce: Eq<"reproduce", "Dump linker invocation and input files for debugging">;
 
 defm rpath: Eq<"rpath", "Add a DT_RUNPATH to the output">;
 

 
 defm symbol_ordering_file:
   Eq<"symbol-ordering-file", "Layout sections to place symbols in the order specified by symbol ordering file">;
 
 defm sysroot: Eq<"sysroot", "Set the system root">;
 
 def target1_rel: F<"target1-rel">, HelpText<"Interpret R_ARM_TARGET1 as R_ARM_REL32">;
 
-def target1_abs: F<"target1-abs">, HelpText<"Interpret R_ARM_TARGET1 as R_ARM_ABS32">;
+def target1_abs: F<"target1-abs">, HelpText<"Interpret R_ARM_TARGET1 as R_ARM_ABS32 (default)">;
 
 defm target2:
   Eq<"target2", "Interpret R_ARM_TARGET2 as <type>, where <type> is one of rel, abs, or got-rel">,
   MetaVarName<"<type>">;
 
 defm threads: B<"threads",
-    "Run the linker multi-threaded",
+    "Run the linker multi-threaded (default)",
     "Do not run the linker multi-threaded">;
 
 def trace: F<"trace">, HelpText<"Print the names of the input files">;
 
 defm trace_symbol: Eq<"trace-symbol", "Trace references to symbols">;
 
 defm undefined: Eq<"undefined", "Force undefined symbol during linking">;
 
 defm unresolved_symbols:
   Eq<"unresolved-symbols", "Determine how to handle unresolved symbols">;
 
 defm undefined_version: B<"undefined-version",
-  "Allow unused version in version script",
+  "Allow unused version in version script (default)",
   "Report version scripts that refer undefined symbols">;
 
 defm rsp_quoting:
   Eq<"rsp-quoting", "Quoting style for response files. Values supported: windows|posix">;
 
 def v: Flag<["-"], "v">, HelpText<"Display the version number">;
 
 def verbose: F<"verbose">, HelpText<"Verbose mode">;
 
 def version: F<"version">, HelpText<"Display the version number and exit">;
 
 defm version_script: Eq<"version-script", "Read a version script">;
 
 defm warn_backrefs: B<"warn-backrefs",
     "Warn about backward symbol references to fetch archive members",
-    "Do not warn about backward symbol references to fetch archive members">;
+    "Do not warn about backward symbol references to fetch archive members (default)">;
 
 defm warn_common: B<"warn-common",
     "Warn about duplicate common symbols",
-    "Do not warn about duplicate common symbols">;
+    "Do not warn about duplicate common symbols (default)">;
 
 defm warn_symbol_ordering : B<"warn-symbol-ordering",
-    "Warn about problems with the symbol ordering file",
+    "Warn about problems with the symbol ordering file (default)",
     "Do not warn about problems with the symbol ordering file">;
 
 def warn_unresolved_symbols: F<"warn-unresolved-symbols">,
   HelpText<"Report unresolved symbols as warnings">;
 
 defm whole_archive: B<"whole-archive",
     "Force load of all members in a static library",
-    "Do not force load of all members in a static library">;
+    "Do not force load of all members in a static library (default)">;
 
 defm wrap: Eq<"wrap", "Use wrapper functions for symbol">,
   MetaVarName<"<symbol>">;
 
 def z: JoinedOrSeparate<["-"], "z">, MetaVarName<"<option>">,
   HelpText<"Linker option extensions">;
 
 // Aliases