r241131 - [Sema] Don't crash when deduction fails for decltype(auto)

[David Majnemer]

Author: majnemer
Date: Tue Jun 30 19:29:28 2015
New Revision: 241131

URL: http://llvm.org/viewvc/llvm-project?rev=241131&view=rev
Log:
[Sema] Don't crash when deduction fails for decltype(auto)

We didn't check the return result of BuildDecltypeType, resulting in us
crashing when we tried to grab the canonical version of the type.

This fixes PR23995.

Modified:
    cfe/trunk/lib/Sema/SemaTemplateDeduction.cpp
    cfe/trunk/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.spec.auto/p7-1y.cpp

Modified: cfe/trunk/lib/Sema/SemaTemplateDeduction.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaTemplateDeduction.cpp?rev=241131&r1=241130&r2=241131&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaTemplateDeduction.cpp (original)
+++ cfe/trunk/lib/Sema/SemaTemplateDeduction.cpp Tue Jun 30 19:29:28 2015
@@ -3968,6 +3968,8 @@ Sema::DeduceAutoType(TypeLoc Type, Expr
       }
 
       QualType Deduced = BuildDecltypeType(Init, Init->getLocStart(), false);
+      if (Deduced.isNull())
+        return DAR_FailedAlreadyDiagnosed;
       // FIXME: Support a non-canonical deduced type for 'auto'.
       Deduced = Context.getCanonicalType(Deduced);
       Result = SubstituteAutoTransform(*this, Deduced).Apply(Type);

Modified: cfe/trunk/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.spec.auto/p7-1y.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.spec.auto/p7-1y.cpp?rev=241131&r1=241130&r2=241131&view=diff
==============================================================================
--- cfe/trunk/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.spec.auto/p7-1y.cpp (original)
+++ cfe/trunk/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.spec.auto/p7-1y.cpp Tue Jun 30 19:29:28 2015
@@ -11,6 +11,9 @@ namespace std {
 int i;
 int &&f();
 
+template <typename T>
+void overloaded_fn(T); // expected-note {{possible target}}
+
 using Int = int;
 using IntLRef = int&;
 using IntRRef = int&&;
@@ -57,6 +60,7 @@ decltype(auto) ((((((v1)))))) = 0; // ok
 decltype(auto) v2[1] = { 0 }; // expected-error {{cannot form array of 'decltype(auto)'}}
 decltype(auto) &v3 = { 0 }; // expected-error {{cannot form reference to 'decltype(auto)'}}
 decltype(auto) *v4 = { 0 }; // expected-error {{cannot form pointer to 'decltype(auto)'}}
+decltype(auto) v5 = &overloaded_fn; // expected-error {{could not be resolved}}
 
 auto multi1a = 0, &multi1b = multi1a;
 auto multi1c = multi1a, multi1d = multi1b;