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

… notes

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) {}
      |            ~~~~~~
```

Reviewed By: cjdb, aaron.ballman

Differential Revision: https://reviews.llvm.org/D153267

clang/docs/ReleaseNotes.rst

@@ -364,6 +364,8 @@ Improvements to Clang's diagnostics
 - The Fix-It emitted for unused labels used to expand to the next line, which caused
   visual oddities now that Clang shows more than one line of code snippet. This has
   been fixed and the Fix-It now only spans to the end of the ``:``.
+- Clang now underlines the parameter list of function declaration when emitting
+  a note about the mismatch in the number of arguments.
 
 Bug Fixes in This Version
 -------------------------

clang/lib/Sema/SemaExpr.cpp

@@ -6459,7 +6459,8 @@ Sema::ConvertArgumentsForCall(CallExpr *Call, Expr *Fn,
 
       // 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;
     }
@@ -6504,7 +6505,8 @@ Sema::ConvertArgumentsForCall(CallExpr *Call, Expr *Fn,
 
       // 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);

clang/lib/Sema/SemaOverload.cpp

@@ -11037,11 +11037,13 @@ static void DiagnoseArityMismatch(Sema &S, NamedDecl *Found, Decl *D,
   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);
 }

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

@@ -0,0 +1,11 @@
+// RUN: not %clang_cc1 -fsyntax-only -fdiagnostics-print-source-range-info %s 2>&1 | FileCheck %s --strict-whitespace
+
+// CHECK:      :{9:3-9:7}: error: too few arguments
+// CHECK:      :{7:12-7:26}: note: 'func' declared here
+// CHECK:      :{10:3-10:7}{10:13-10:17}: error: too many arguments
+// CHECK:      :{7:12-7:26}: note: 'func' declared here
+void func( int aa, int bb) {}
+void arity_mismatch() {
+  func(3);
+  func(3, 4,5, 6);
+}

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

@@ -0,0 +1,14 @@
+// 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() {
+  func(2, 4);
+}