[AsmParser]Emit an error if a macro has two (or more) parameters sharing the same name

[coby]

Summary

Introducing a new error to macro parameters' parsing:
currently, llvm-mc won't complain if a macro have two (or more) named params with the same name.
this behavior is false, as there's no merit in having some params sharing a name.
now, instead of tolerate such a phenomena - emit an appropriate error.

[coby]

please add any other reviewers you may see as fitting here

[rengolin]

test/MC/AsmParser/macro-duplicate-params-names-err.s

1 ↗

(On Diff #94096)

This will fail on bots that don't build x86. Either remove the triple or move the test to an x86-specific test.

[compnerd]

Please address the issue that @rengolin pointed out. There is no reason to have an explicit triple here, as the test is agnostic. Just drop the nop in the macro.

lib/MC/MCParser/AsmParser.cpp

3880 ↗

(On Diff #94096)

I think I would prefer multiple rather than at least two.

[coby]

thanks for the detailed and prompt response
commited version will reflect requested modifications

llvm/trunk/lib/MC/MCParser/AsmParser.cpp

if (!Parameters.empty() && Parameters.back().Vararg)
       return Error(Lexer.getLoc(),
                    "Vararg parameter '" + Parameters.back().Name +
                    "' should be last one in the list of parameters.");
 
     MCAsmMacroParameter Parameter;
     if (parseIdentifier(Parameter.Name))
       return TokError("expected identifier in '.macro' directive");
 
+    // Emit an error if two (or more) named parameters share the same name
+    for (const MCAsmMacroParameter& CurrParam : Parameters)
+      if (CurrParam.Name.equals(Parameter.Name))
+        return TokError("macro '" + Name + "' has multiple parameters"
+                        " named '" + Parameter.Name + "'");
+
     if (Lexer.is(AsmToken::Colon)) {
       Lex();  // consume ':'
 
       SMLoc QualLoc;
       StringRef Qualifier;
 
       QualLoc = Lexer.getLoc();
       if (parseIdentifier(Qualifier))

llvm/trunk/test/MC/AsmParser/macro-duplicate-params-names-err.s

+// RUN: not llvm-mc %s 2> %t
+// RUN: FileCheck < %t %s
+
+.macro M a a
+.endm
+
+// CHECK: macro 'M' has multiple parameters named 'a'