Produce detailed diagnostics when overload
resolution failed to select a candidate due to
ambiguity in type conversion function selection.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@82596 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaOverload.cpp b/lib/Sema/SemaOverload.cpp
index acfc326..144cf93 100644
--- a/lib/Sema/SemaOverload.cpp
+++ b/lib/Sema/SemaOverload.cpp
@@ -411,13 +411,15 @@
bool InOverloadResolution) {
ImplicitConversionSequence ICS;
OverloadCandidateSet Conversions;
+ OverloadingResult UserDefResult = OR_Success;
if (IsStandardConversion(From, ToType, InOverloadResolution, ICS.Standard))
ICS.ConversionKind = ImplicitConversionSequence::StandardConversion;
else if (getLangOptions().CPlusPlus &&
- IsUserDefinedConversion(From, ToType, ICS.UserDefined,
+ (UserDefResult = IsUserDefinedConversion(From, ToType,
+ ICS.UserDefined,
Conversions,
!SuppressUserConversions, AllowExplicit,
- ForceRValue) == OR_Success) {
+ ForceRValue)) == OR_Success) {
ICS.ConversionKind = ImplicitConversionSequence::UserDefinedConversion;
// C++ [over.ics.user]p4:
// A conversion of an expression of class type to the same class
@@ -454,8 +456,14 @@
if (SuppressUserConversions &&
ICS.ConversionKind == ImplicitConversionSequence::UserDefinedConversion)
ICS.ConversionKind = ImplicitConversionSequence::BadConversion;
- } else
+ } else {
ICS.ConversionKind = ImplicitConversionSequence::BadConversion;
+ if (UserDefResult == OR_Ambiguous) {
+ for (OverloadCandidateSet::iterator Cand = Conversions.begin();
+ Cand != Conversions.end(); ++Cand)
+ ICS.ConversionFunctionSet.push_back(Cand->Function);
+ }
+ }
return ICS;
}
@@ -3868,8 +3876,27 @@
*Cand->Function->getTemplateSpecializationArgs());
} else {
// Normal function
- // FIXME: Give a better reason!
- Diag(Cand->Function->getLocation(), diag::err_ovl_candidate);
+ bool errReported = false;
+ if (!Cand->Viable && Cand->Conversions.size() > 0) {
+ for (int i = Cand->Conversions.size()-1; i >= 0; i--) {
+ const ImplicitConversionSequence &Conversion =
+ Cand->Conversions[i];
+ if ((Conversion.ConversionKind !=
+ ImplicitConversionSequence::BadConversion) ||
+ Conversion.ConversionFunctionSet.size() == 0)
+ continue;
+ Diag(Cand->Function->getLocation(),
+ diag::err_ovl_candidate_not_viable) << (i+1);
+ errReported = true;
+ for (int j = Conversion.ConversionFunctionSet.size()-1;
+ j >= 0; j--) {
+ FunctionDecl *Func = Conversion.ConversionFunctionSet[j];
+ Diag(Func->getLocation(), diag::err_ovl_candidate);
+ }
+ }
+ }
+ if (!errReported)
+ Diag(Cand->Function->getLocation(), diag::err_ovl_candidate);
}
} else if (Cand->IsSurrogate) {
// Desugar the type of the surrogate down to a function type,
diff --git a/lib/Sema/SemaOverload.h b/lib/Sema/SemaOverload.h
index 1f3e4df..17f5598 100644
--- a/lib/Sema/SemaOverload.h
+++ b/lib/Sema/SemaOverload.h
@@ -195,7 +195,11 @@
/// details of the user-defined conversion sequence.
UserDefinedConversionSequence UserDefined;
};
-
+
+ /// When ConversionKind == BadConversion due to multiple conversion
+ /// functions, this will list those functions.
+ llvm::SmallVector<FunctionDecl*, 4> ConversionFunctionSet;
+
// The result of a comparison between implicit conversion
// sequences. Use Sema::CompareImplicitConversionSequences to
// actually perform the comparison.