Implement most of N3638 (return type deduction for normal functions).

Missing (somewhat ironically) is support for the new deduction rules
in lambda functions, plus PCH support for return type patching.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@181108 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 12 insertions, 0 deletions

diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 60dbdc14be..2acbe5961e 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -55,6 +55,12 @@ bool Sema::CanUseDecl(NamedDecl *D) {
   if (FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
     if (FD->isDeleted())
       return false;
+
+    // If the function has a deduced return type, and we can't deduce it,
+    // then we can't use it either.
+    if (getLangOpts().CPlusPlus1y && FD->getResultType()->isUndeducedType() &&
+        DeduceReturnType(FD, SourceLocation(), /*Diagnose*/false))
+      return false;
   }
 
   // See if this function is unavailable.
@@ -278,6 +284,12 @@ bool Sema::DiagnoseUseOfDecl(NamedDecl *D, SourceLocation Loc,
       NoteDeletedFunction(FD);
       return true;
     }
+
+    // If the function has a deduced return type, and we can't deduce it,
+    // then we can't use it either.
+    if (getLangOpts().CPlusPlus1y && FD->getResultType()->isUndeducedType() &&
+        DeduceReturnType(FD, Loc))
+      return true;
   }
   DiagnoseAvailabilityOfDecl(*this, D, Loc, UnknownObjCClass);