[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.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@241131 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Sema/SemaTemplateDeduction.cpp b/lib/Sema/SemaTemplateDeduction.cpp
index 02e59af558b23fb32268ad290dfd6af213aa3317..ae8157e70a603b38fc3d2de100cab0794d3c837d 100644 (file)
--- a/lib/Sema/SemaTemplateDeduction.cpp
+++ b/lib/Sema/SemaTemplateDeduction.cpp
@@ -3968,6 +3968,8 @@ Sema::DeduceAutoType(TypeLoc Type, Expr *&Init, QualType &Result) {
       }
 
       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);

diff --git a/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.spec.auto/p7-1y.cpp b/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.spec.auto/p7-1y.cpp
index f7b3e8e7be6321db659743fff5dd0c35b7dc78f6..c3dc1de3ed6f1d969ae8f48c745b286e9819fe1f 100644 (file)
--- a/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.spec.auto/p7-1y.cpp
+++ b/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.spec.auto/p7-1y.cpp
@@ -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;