patch via mailing list: Use getLocation() in too few/many arguments diagnostic

[John Marshall via cfe-commits]

This small patch improves the diagnostics when calling a function with the wrong number of arguments. For example, given

	int
	foo(int a, int b);

	int bar() { return foo(1); }

The existing compiler shows the error message and a note for "foo declared here" showing only the "int" line. Ideally it would show the line containing the word "foo" instead, which it does after this patch. Also if the function declaration starts with some incidental macro, a trace of macro expansion is shown which is likely irrelevant. See for example https://github.com/samtools/htslib/issues/1013 and PR#23564.

I have not contributed to LLVM before and I am unfamiliar with the difference between getBeginLoc() and getLocation() and the implications of using each. However this patch does fix PR#23564 and perhaps this fix would be mostly a no-brainer for those who are familiar with the code and these two location functions in particular?

Thanks,

    John


commit 12c8979abaf40aa76c6769d6270f3565d71f3011
Author: John Marshall <John.W.Marshall at glasgow.ac.uk>
Date:   Mon Jan 20 14:58:14 2020 +0000

    Use getLocation() in too few/many arguments diagnostic
    
    Use the more accurate location when emitting the location of the
    function being called's prototype in diagnostics emitted when calling
    a function with an incorrect number of arguments.
    
    In particular, avoids showing a trace of irrelevant macro expansions
    for "MY_EXPORT static int AwesomeFunction(int, int);". Fixes PR#23564.

diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index ea4b93ee6a5..19dfc7c7fd7 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -5194,7 +5194,7 @@ Sema::ConvertArgumentsForCall(CallExpr *Call, Expr *Fn,
 
       // Emit the location of the prototype.
       if (!TC && FDecl && !FDecl->getBuiltinID() && !IsExecConfig)
-        Diag(FDecl->getBeginLoc(), diag::note_callee_decl) << FDecl;
+        Diag(FDecl->getLocation(), diag::note_callee_decl) << FDecl;
 
       return true;
     }
@@ -5239,7 +5239,7 @@ Sema::ConvertArgumentsForCall(CallExpr *Call, Expr *Fn,
 
       // Emit the location of the prototype.
       if (!TC && FDecl && !FDecl->getBuiltinID() && !IsExecConfig)
-        Diag(FDecl->getBeginLoc(), diag::note_callee_decl) << FDecl;
+        Diag(FDecl->getLocation(), diag::note_callee_decl) << FDecl;
 
       // This deletes the extra arguments.
       Call->shrinkNumArgs(NumParams);