[Sema] Teach overload resolution about unaddressable functions.

Given an expression like `(&Foo)();`, we perform overload resolution as
if we are calling `Foo` directly. This causes problems if `Foo` is a
function that can't have its address taken. This patch teaches overload
resolution to ignore functions that can't have their address taken in
such cases.

Differential Revision: http://reviews.llvm.org/D15590

llvm-svn: 257016

1 files changed, 14 insertions, 3 deletions

diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 8e50d5a103c..67d5db15cf2 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -4935,7 +4935,9 @@ Sema::ActOnCallExpr(Scope *S, Expr *Fn, SourceLocation LParenLoc,
       OverloadExpr *ovl = find.Expression;
       if (UnresolvedLookupExpr *ULE = dyn_cast<UnresolvedLookupExpr>(ovl))
         return BuildOverloadedCallExpr(S, Fn, ULE, LParenLoc, ArgExprs,
-                                       RParenLoc, ExecConfig);
+                                       RParenLoc, ExecConfig,
+                                       /*AllowTypoCorrection=*/true,
+                                       find.IsAddressOfOperand);
       return BuildCallToMemberFunction(S, Fn, LParenLoc, ArgExprs, RParenLoc);
     }
   }
@@ -4949,10 +4951,14 @@ Sema::ActOnCallExpr(Scope *S, Expr *Fn, SourceLocation LParenLoc,
 
   Expr *NakedFn = Fn->IgnoreParens();
 
+  bool CallingNDeclIndirectly = false;
   NamedDecl *NDecl = nullptr;
-  if (UnaryOperator *UnOp = dyn_cast<UnaryOperator>(NakedFn))
-    if (UnOp->getOpcode() == UO_AddrOf)
+  if (UnaryOperator *UnOp = dyn_cast<UnaryOperator>(NakedFn)) {
+    if (UnOp->getOpcode() == UO_AddrOf) {
+      CallingNDeclIndirectly = true;
       NakedFn = UnOp->getSubExpr()->IgnoreParens();
+    }
+  }
 
   if (isa<DeclRefExpr>(NakedFn)) {
     NDecl = cast<DeclRefExpr>(NakedFn)->getDecl();
@@ -4974,6 +4980,11 @@ Sema::ActOnCallExpr(Scope *S, Expr *Fn, SourceLocation LParenLoc,
     NDecl = cast<MemberExpr>(NakedFn)->getMemberDecl();
 
   if (FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(NDecl)) {
+    if (CallingNDeclIndirectly &&
+        !checkAddressOfFunctionIsAvailable(FD, /*Complain=*/true,
+                                           Fn->getLocStart()))
+      return ExprError();
+
     if (FD->hasAttr<EnableIfAttr>()) {
       if (const EnableIfAttr *Attr = CheckEnableIf(FD, ArgExprs, true)) {
         Diag(Fn->getLocStart(),