Downgrade complaints about calling unavailable functions to a warning

(as GCC does), except when we've performed overload resolution and
found an unavailable function: in this case, we actually error.

Merge the checking of unavailable functions with the checking for
deprecated functions. This unifies a bit of code, and makes sure that
we're checking for unavailable functions in the right places. Also,
this check can cause an error. We may, eventually, want an option to
make "unavailable" warnings into errors.

Implement much of the logic needed for C++0x deleted functions, which
are effectively the same as "unavailable" functions (but always cause
an error when referenced). However, we don't have the syntax to
specify deleted functions yet :)



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@64955 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 51 insertions, 2 deletions

diff --git a/lib/Sema/SemaOverload.cpp b/lib/Sema/SemaOverload.cpp
index ffb29795f5..f2c7de2fae 100644
--- a/lib/Sema/SemaOverload.cpp
+++ b/lib/Sema/SemaOverload.cpp
@@ -1409,6 +1409,7 @@ bool Sema::IsUserDefinedConversion(Expr *From, QualType ToType,
       }
       
     case OR_No_Viable_Function:
+    case OR_Deleted:
       // No conversion here! We're done.
       return false;
 
@@ -3426,6 +3427,14 @@ Sema::BestViableFunction(OverloadCandidateSet& CandidateSet,
   }
   
   // Best is the best viable function.
+  if (Best->Function &&
+      (Best->Function->isDeleted() || 
+       Best->Function->getAttr<UnavailableAttr>()))
+    return OR_Deleted;
+
+  // If Best refers to a function that is either deleted (C++0x) or
+  // unavailable (Clang extension) report an error.
+
   return OR_Success;
 }
 
@@ -3441,8 +3450,16 @@ Sema::PrintOverloadCandidates(OverloadCandidateSet& CandidateSet,
   for (; Cand != LastCand; ++Cand) {
     if (Cand->Viable || !OnlyViable) {
       if (Cand->Function) {
-        // Normal function
-        Diag(Cand->Function->getLocation(), diag::err_ovl_candidate);
+        if (Cand->Function->isDeleted() ||
+            Cand->Function->getAttr<UnavailableAttr>()) {
+          // Deleted or "unavailable" function.
+          Diag(Cand->Function->getLocation(), diag::err_ovl_candidate_deleted)
+            << Cand->Function->isDeleted();
+        } else {
+          // Normal function
+          // FIXME: Give a better reason!
+          Diag(Cand->Function->getLocation(), diag::err_ovl_candidate);
+        }
       } else if (Cand->IsSurrogate) {
         // Desugar the type of the surrogate down to a function type,
         // retaining as many typedefs as possible while still showing
@@ -3644,6 +3661,14 @@ FunctionDecl *Sema::ResolveOverloadedCallFn(Expr *Fn, NamedDecl *Callee,
       << UnqualifiedName << Fn->getSourceRange();
     PrintOverloadCandidates(CandidateSet, /*OnlyViable=*/true);
     break;
+
+  case OR_Deleted:
+    Diag(Fn->getSourceRange().getBegin(), diag::err_ovl_deleted_call)
+      << Best->Function->isDeleted()
+      << UnqualifiedName
+      << Fn->getSourceRange();
+    PrintOverloadCandidates(CandidateSet, /*OnlyViable=*/true);
+    break;
   }
 
   // Overload resolution failed. Destroy all of the subexpressions and
@@ -3716,6 +3741,15 @@ Sema::BuildCallToMemberFunction(Scope *S, Expr *MemExprE,
       PrintOverloadCandidates(CandidateSet, /*OnlyViable=*/false);
       // FIXME: Leaking incoming expressions!
       return true;
+
+    case OR_Deleted:
+      Diag(MemExpr->getSourceRange().getBegin(), 
+           diag::err_ovl_deleted_member_call)
+        << Best->Function->isDeleted()
+        << Ovl->getDeclName() << MemExprE->getSourceRange();
+      PrintOverloadCandidates(CandidateSet, /*OnlyViable=*/false);
+      // FIXME: Leaking incoming expressions!
+      return true;
     }
 
     FixOverloadedFunctionReference(MemExpr, Method);
@@ -3831,6 +3865,14 @@ Sema::BuildCallToObjectOfClassType(Scope *S, Expr *Object,
       << Object->getType() << Object->getSourceRange();
     PrintOverloadCandidates(CandidateSet, /*OnlyViable=*/true);
     break;
+
+  case OR_Deleted:
+    Diag(Object->getSourceRange().getBegin(),
+         diag::err_ovl_deleted_object_call)
+      << Best->Function->isDeleted()
+      << Object->getType() << Object->getSourceRange();
+    PrintOverloadCandidates(CandidateSet, /*OnlyViable=*/true);
+    break;
   }    
 
   if (Best == CandidateSet.end()) {
@@ -3990,6 +4032,13 @@ Sema::BuildOverloadedArrowExpr(Scope *S, Expr *Base, SourceLocation OpLoc,
       << "operator->" << BasePtr->getSourceRange();
     PrintOverloadCandidates(CandidateSet, /*OnlyViable=*/true);
     return true;
+
+  case OR_Deleted:
+    Diag(OpLoc,  diag::err_ovl_deleted_oper)
+      << Best->Function->isDeleted()
+      << "operator->" << BasePtr->getSourceRange();
+    PrintOverloadCandidates(CandidateSet, /*OnlyViable=*/true);
+    return true;
   }
 
   // Convert the object parameter.