lld: Add --color-diagnostic to MachO port, harmonize others

This adds `--[no-]color-diagnostics[=auto,never,always]` to
the MachO port and harmonizes the flag in the other ports:
- Consistently use MetaVarName
- Consistently document the non-eq version as alias of the eq version
- Use B<> in the ports that have it (no-op, shorter)
- Fix oversight in COFF port that made the --no flag have the wrong
  prefix

Differential Revision: https://reviews.llvm.org/D91640

2 files changed, 36 insertions, 0 deletions

diff --git a/lld/MachO/Driver.cpp b/lld/MachO/Driver.cpp
index 6735611666a9..a693cf6c8033 100644
--- a/lld/MachO/Driver.cpp
+++ b/lld/MachO/Driver.cpp
@@ -69,6 +69,28 @@ static const opt::OptTable::Info optInfo[] = {
 
 MachOOptTable::MachOOptTable() : OptTable(optInfo) {}
 
+// Set color diagnostics according to --color-diagnostics={auto,always,never}
+// or --no-color-diagnostics flags.
+static void handleColorDiagnostics(opt::InputArgList &args) {
+  auto *arg = args.getLastArg(OPT_color_diagnostics, OPT_color_diagnostics_eq,
+                              OPT_no_color_diagnostics);
+  if (!arg)
+    return;
+  if (arg->getOption().getID() == OPT_color_diagnostics) {
+    lld::errs().enable_colors(true);
+  } else if (arg->getOption().getID() == OPT_no_color_diagnostics) {
+    lld::errs().enable_colors(false);
+  } else {
+    StringRef s = arg->getValue();
+    if (s == "always")
+      lld::errs().enable_colors(true);
+    else if (s == "never")
+      lld::errs().enable_colors(false);
+    else if (s != "auto")
+      error("unknown option: --color-diagnostics=" + s);
+  }
+}
+
 opt::InputArgList MachOOptTable::parse(ArrayRef<const char *> argv) {
   // Make InputArgList from string vectors.
   unsigned missingIndex;
@@ -80,6 +102,8 @@ opt::InputArgList MachOOptTable::parse(ArrayRef<const char *> argv) {
   if (missingCount)
     error(Twine(args.getArgString(missingIndex)) + ": missing argument");
 
+  handleColorDiagnostics(args);
+
   for (opt::Arg *arg : args.filtered(OPT_UNKNOWN))
     error("unknown argument: " + arg->getSpelling());
   return args;
diff --git a/lld/MachO/Options.td b/lld/MachO/Options.td
index cdbdbb26702e..3695bd1e2868 100644
--- a/lld/MachO/Options.td
+++ b/lld/MachO/Options.td
@@ -1,8 +1,20 @@
 include "llvm/Option/OptParser.td"
 
+// Flags that lld/MachO understands but ld64 doesn't. These take
+// '--' instead of '-' and use dashes instead of underscores, so
+// they don't collide with the ld64 compat options.
+
 def help : Flag<["-", "--"], "help">;
 def help_hidden : Flag<["--"], "help-hidden">,
   HelpText<"Display help for hidden options">;
+def color_diagnostics: Flag<["--"], "color-diagnostics">,
+  HelpText<"Alias for --color-diagnostics=always">;
+def no_color_diagnostics: Flag<["--"], "no-color-diagnostics">,
+  HelpText<"Alias for --color-diagnostics=never">;
+def color_diagnostics_eq: Joined<["--"], "color-diagnostics=">,
+  HelpText<"Use colors in diagnostics (default: auto)">,
+  MetaVarName<"[auto,always,never]">;
+
 
 // This is a complete Options.td compiled from Apple's ld(1) manpage
 // dated 2018-03-07 and cross checked with ld64 source code in repo