[clang][Diagnostics] Provide parameter source range to arity-mismatch notes

[hazohelet]

Summary

Consider the following piece of code:

void func( int aa,
           int bb,
           int cc) {}

void arity_mismatch() {
  func(2, 4);
}

BEFORE:

source.cpp:6:3: error: no matching function for call to 'func'
    6 |   func(2, 4);
      |   ^~~~
source.cpp:1:6: note: candidate function not viable: requires 3 arguments, but 2 were provided
    1 | void func( int aa,
      |      ^

AFTER:

source.cpp:6:3: error: no matching function for call to 'func'
    6 |   func(2, 4);
      |   ^~~~
source.cpp:1:6: note: candidate function not viable: requires 3 arguments, but 2 were provided
    1 | void func( int aa,
      |      ^     ~~~~~~~
    2 |            int bb,
      |            ~~~~~~~
    3 |            int cc) {}
      |            ~~~~~~

[tbaeder]

LGTM but let's wait for a second opinion.

[cjdb]

I think this will be a good addition because it underscores the salient part of why the function isn't viable.

Would it be possible for patches like this to have both examples of before and after this patch in their commit message please? That'll help expose why patches like this are desirable. Happy to LGTM afterwards.

clang/test/Misc/diag-func-call-ranges.cpp

13

Why are you casting to void?

[aaron.ballman]

LGTM modulo Chris' comment, but can you please add a release note for the fix?

[hazohelet]

Address comments from @cjdb and @aaron.ballman

• Remove unnecessary cast to void in test
• Add release note

[cjdb]

Thanks! This LGTM now. Do you need assistance with merging?

[hazohelet]

In D153267#4445417, @cjdb wrote:

Thanks! This LGTM now. Do you need assistance with merging?

Thanks for the review! I have commit access now, so I'll be landing this myself.

clang/lib/Sema/SemaExpr.cpp

if (Args.size() < MinArgs) {
         Diag(RParenLoc, MinArgs == NumParams && !Proto->isVariadic()
                             ? diag::err_typecheck_call_too_few_args
                             : diag::err_typecheck_call_too_few_args_at_least)
             << FnKind << MinArgs << static_cast<unsigned>(Args.size())
             << Fn->getSourceRange();
 
       // Emit the location of the prototype.
       if (!TC && FDecl && !FDecl->getBuiltinID() && !IsExecConfig)
-        Diag(FDecl->getLocation(), diag::note_callee_decl) << FDecl;
+        Diag(FDecl->getLocation(), diag::note_callee_decl)
+            << FDecl << FDecl->getParametersSourceRange();
 
       return true;
     }
     // We reserve space for the default arguments when we create
     // the call expression, before calling ConvertArgumentsForCall.
     assert((Call->getNumArgs() == NumParams) &&
            "We should have reserved space for the default arguments before!");
   }
if (!Proto->isVariadic()) {
                  : diag::err_typecheck_call_too_many_args_at_most)
             << FnKind << NumParams << static_cast<unsigned>(Args.size())
             << Fn->getSourceRange()
             << SourceRange(Args[NumParams]->getBeginLoc(),
                            Args.back()->getEndLoc());
 
       // Emit the location of the prototype.
       if (!TC && FDecl && !FDecl->getBuiltinID() && !IsExecConfig)
-        Diag(FDecl->getLocation(), diag::note_callee_decl) << FDecl;
+        Diag(FDecl->getLocation(), diag::note_callee_decl)
+            << FDecl << FDecl->getParametersSourceRange();
 
       // This deletes the extra arguments.
       Call->shrinkNumArgs(NumParams);
       return true;
     }
   }
   SmallVector<Expr *, 8> AllArgs;
   VariadicCallType CallType = getVariadicCallType(FDecl, Proto, Fn);

clang/lib/Sema/SemaOverload.cpp

static void DiagnoseArityMismatch(Sema &S, NamedDecl *Found, Decl *D,
 
   std::string Description;
   std::pair<OverloadCandidateKind, OverloadCandidateSelect> FnKindPair =
       ClassifyOverloadCandidate(S, Found, Fn, CRK_None, Description);
 
   if (modeCount == 1 && Fn->getParamDecl(0)->getDeclName())
     S.Diag(Fn->getLocation(), diag::note_ovl_candidate_arity_one)
         << (unsigned)FnKindPair.first << (unsigned)FnKindPair.second
-        << Description << mode << Fn->getParamDecl(0) << NumFormalArgs;
+        << Description << mode << Fn->getParamDecl(0) << NumFormalArgs
+        << Fn->getParametersSourceRange();
   else
     S.Diag(Fn->getLocation(), diag::note_ovl_candidate_arity)
         << (unsigned)FnKindPair.first << (unsigned)FnKindPair.second
-        << Description << mode << modeCount << NumFormalArgs;
+        << Description << mode << modeCount << NumFormalArgs
+        << Fn->getParametersSourceRange();
 
   MaybeEmitInheritedConstructorNote(S, Found);
 }
 
 /// Arity mismatch diagnosis specific to a function overload candidate.
 static void DiagnoseArityMismatch(Sema &S, OverloadCandidate *Cand,
                                   unsigned NumFormalArgs) {
   if (!CheckArityMismatch(S, Cand, NumFormalArgs))

clang/test/Misc/diag-func-call-ranges.c

+// RUN: not %clang_cc1 -fsyntax-only -fdiagnostics-print-source-range-info %s 2>&1 | FileCheck %s --strict-whitespace
+
+// CHECK:      :{9:10-9:14}: error: too few arguments
+// CHECK:      :{7:12-7:26}: note: 'func' declared here
+// CHECK:      :{10:10-10:14}{10:20-10:24}: error: too many arguments
+// CHECK:      :{7:12-7:26}: note: 'func' declared here
+void func( int aa, int bb) {}
+void arity_mismatch() {
+  (void)(func(3));
+  (void)(func(3, 4,5, 6));
+}

clang/test/Misc/diag-func-call-ranges.cpp

+// RUN: not %clang_cc1 -fsyntax-only -fdiagnostics-print-source-range-info %s 2>&1 | FileCheck %s --strict-whitespace
+
+// CHECK: error: no matching function for call to 'func'
+
+// CHECK:      :{[[@LINE+1]]:12-[[@LINE+1]]:18}: note: {{.*}} requires single argument
+void func( int aa ) {}
+// CHECK:      :{[[@LINE+1]]:12-[[@LINE+3]]:18}: note: {{.*}} requires 3 arguments
+void func( int aa,
+           int bb,
+           int cc) {}
+
+void arity_mismatch() {
+  (void)func(2, 4);
+}