[lld/mac] Don't warn on both --icf=all and -no_deduplicate

[thakis]

Summary

Instead, just make the later flag win, like usual.
Implement this by making -no_deduplicate an actual alias for --icf=none
at the Options.td level.

[int3]

Implement this by making -no_deduplicate an actual alias for --icf=all

I guess you meant =none :)

[thakis]

Thanks!

(Fixed patch description.)

lld/MachO/Driver.cpp

if (treatment == UndefinedSymbolTreatment::unknown) {
     else
       error("'-undefined suppress' only valid with '-flat_namespace'");
     treatment = UndefinedSymbolTreatment::error;
   }
   return treatment;
 }
 
 static ICFLevel getICFLevel(const ArgList &args) {
-  bool noDeduplicate = args.hasArg(OPT_no_deduplicate);
   StringRef icfLevelStr = args.getLastArgValue(OPT_icf_eq);
   auto icfLevel = StringSwitch<ICFLevel>(icfLevelStr)
                       .Cases("none", "", ICFLevel::none)
                       .Case("safe", ICFLevel::safe)
                       .Case("all", ICFLevel::all)
                       .Default(ICFLevel::unknown);
   if (icfLevel == ICFLevel::unknown) {
     warn(Twine("unknown --icf=OPTION `") + icfLevelStr +
          "', defaulting to `none'");
     icfLevel = ICFLevel::none;
-  } else if (icfLevel != ICFLevel::none && noDeduplicate) {
-    warn(Twine("`--icf=" + icfLevelStr +
-               "' conflicts with -no_deduplicate, setting to `none'"));
-    icfLevel = ICFLevel::none;
   } else if (icfLevel == ICFLevel::safe) {
     warn(Twine("`--icf=safe' is not yet implemented, reverting to `none'"));
     icfLevel = ICFLevel::none;
   }
   return icfLevel;
 }
 
 static void warnIfDeprecatedOption(const Option &opt) {

lld/MachO/Options.td

def merge_zero_fill_sections : Flag<["-"], "merge_zero_fill_sections">,
     Flags<[HelpHidden]>,
     Group<grp_opts>;
 def no_branch_islands : Flag<["-"], "no_branch_islands">,
     HelpText<"Disable infra for branches beyond the maximum branch distance.">,
     Flags<[HelpHidden]>,
     Group<grp_opts>;
 def no_deduplicate : Flag<["-"], "no_deduplicate">,
     HelpText<"Disable code deduplicaiton (synonym for `--icf=none')">,
+    Alias<icf_eq>, AliasArgs<["none"]>,
     Group<grp_opts>;
 
 def grp_version : OptionGroup<"version">, HelpText<"VERSION TARGETING">;
 
 def platform_version : MultiArg<["-"], "platform_version", 3>,
     MetaVarName<"<platform> <min_version> <sdk_version>">,
     HelpText<"Platform (e.g., macos, ios, tvos, watchos, bridgeos, mac-catalyst, ios-sim, tvos-sim, watchos-sim, driverkit) and version numbers">,
     Group<grp_version>;

lld/test/MachO/icf-options.s

 # REQUIRES: x86
 # RUN: rm -rf %t; mkdir %t
 
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %s -o %t/main.o
 # RUN: %lld -lSystem --icf=all -o %t/all %t/main.o 2>&1 \
 # RUN:     | FileCheck %s --check-prefix=DIAG-EMPTY --allow-empty
 # RUN: %lld -lSystem --icf=none -o %t/none %t/main.o 2>&1 \
 # RUN:     | FileCheck %s --check-prefix=DIAG-EMPTY --allow-empty
 # RUN: %lld -lSystem -no_deduplicate -o %t/no_dedup %t/main.o 2>&1 \
 # RUN:     | FileCheck %s --check-prefix=DIAG-EMPTY --allow-empty
 # RUN: not %lld -lSystem --icf=safe -o %t/safe %t/main.o 2>&1 \
 # RUN:     | FileCheck %s --check-prefix=DIAG-SAFE
 # RUN: not %lld -lSystem --icf=junk -o %t/junk %t/main.o 2>&1 \
 # RUN:     | FileCheck %s --check-prefix=DIAG-JUNK
-# RUN: not %lld -lSystem --icf=all -no_deduplicate -o %t/clash %t/main.o 2>&1 \
-# RUN:     | FileCheck %s --check-prefix=DIAG-CLASH
+# RUN: %lld -lSystem --icf=all -no_deduplicate -o %t/none2 %t/main.o 2>&1 \
+# RUN:     | FileCheck %s --check-prefix=DIAG-EMPTY --allow-empty
+# RUN: %lld -lSystem -no_deduplicate --icf=all -o %t/all2 %t/main.o 2>&1 \
+# RUN:     | FileCheck %s --check-prefix=DIAG-EMPTY --allow-empty
 
 # DIAG-EMPTY-NOT: {{.}}
 # DIAG-SAFE: `--icf=safe' is not yet implemented, reverting to `none'
 # DIAG-JUNK: unknown --icf=OPTION `junk', defaulting to `none'
-# DIAG-CLASH: `--icf=all' conflicts with -no_deduplicate, setting to `none'
 
 # RUN: llvm-objdump -d --syms %t/all | FileCheck %s --check-prefix=FOLD
+# RUN: llvm-objdump -d --syms %t/all2 | FileCheck %s --check-prefix=FOLD
 # RUN: llvm-objdump -d --syms %t/none | FileCheck %s --check-prefix=NOOP
+# RUN: llvm-objdump -d --syms %t/none2 | FileCheck %s --check-prefix=NOOP
 # RUN: llvm-objdump -d --syms %t/no_dedup | FileCheck %s --check-prefix=NOOP
 
 # FOLD-LABEL: SYMBOL TABLE:
 # FOLD:       [[#%x,MAIN:]] g   F __TEXT,__text _main
 # FOLD:       [[#%x,F:]]    g   F __TEXT,__text _f1
 # FOLD:       [[#%x,F]]     g   F __TEXT,__text _f2
 
 # FOLD-LABEL: Disassembly of section __TEXT,__text: