[Sema] Use a TreeTransform to extract deduction guide parameter types

Previously, we just canonicalized the type, but this lead to crashes with
parameter types that referred to ParmVarDecls of the constructor. There may be
more cases that this TreeTransform needs to handle though, such as a constructor
parameter type referring to a member in an unevaluated context. Canonicalization
doesn't address these cases either though, so we can address them as-needed in
follow-up commits.

rdar://41330135

Differential revision: https://reviews.llvm.org/D49439

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@338165 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Sema/SemaTemplate.cpp b/lib/Sema/SemaTemplate.cpp
index dd1163267119a05941ac9c21317eec0ffb957fc9..919bc7b63d59f87894beb5d53fd81a23fc1fef22 100644 (file)
--- a/lib/Sema/SemaTemplate.cpp
+++ b/lib/Sema/SemaTemplate.cpp
@@ -1659,6 +1659,23 @@ DeclResult Sema::CheckClassTemplate(
 }
 
 namespace {
+/// Tree transform to "extract" a transformed type from a class template's
+/// constructor to a deduction guide.
+class ExtractTypeForDeductionGuide
+  : public TreeTransform<ExtractTypeForDeductionGuide> {
+public:
+  typedef TreeTransform<ExtractTypeForDeductionGuide> Base;
+  ExtractTypeForDeductionGuide(Sema &SemaRef) : Base(SemaRef) {}
+
+  TypeSourceInfo *transform(TypeSourceInfo *TSI) { return TransformType(TSI); }
+
+  QualType TransformTypedefType(TypeLocBuilder &TLB, TypedefTypeLoc TL) {
+    return TransformType(
+        TLB,
+        TL.getTypedefNameDecl()->getTypeSourceInfo()->getTypeLoc());
+  }
+};
+
 /// Transform to convert portions of a constructor declaration into the
 /// corresponding deduction guide, per C++1z [over.match.class.deduct]p1.
 struct ConvertConstructorToDeductionGuideTransform {
@@ -1880,9 +1897,7 @@ private:
                              MultiLevelTemplateArgumentList &Args) {
     TypeSourceInfo *OldDI = OldParam->getTypeSourceInfo();
     TypeSourceInfo *NewDI;
-    if (!Args.getNumLevels())
-      NewDI = OldDI;
-    else if (auto PackTL = OldDI->getTypeLoc().getAs<PackExpansionTypeLoc>()) {
+    if (auto PackTL = OldDI->getTypeLoc().getAs<PackExpansionTypeLoc>()) {
       // Expand out the one and only element in each inner pack.
       Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(SemaRef, 0);
       NewDI =
@@ -1898,23 +1913,17 @@ private:
     if (!NewDI)
       return nullptr;
 
-    // Canonicalize the type. This (for instance) replaces references to
-    // typedef members of the current instantiations with the definitions of
-    // those typedefs, avoiding triggering instantiation of the deduced type
-    // during deduction.
-    // FIXME: It would be preferable to retain type sugar and source
-    // information here (and handle this in substitution instead).
-    NewDI = SemaRef.Context.getTrivialTypeSourceInfo(
-        SemaRef.Context.getCanonicalType(NewDI->getType()),
-        OldParam->getLocation());
+    // Extract the type. This (for instance) replaces references to typedef
+    // members of the current instantiations with the definitions of those
+    // typedefs, avoiding triggering instantiation of the deduced type during
+    // deduction.
+    NewDI = ExtractTypeForDeductionGuide(SemaRef).transform(NewDI);
 
     // Resolving a wording defect, we also inherit default arguments from the
     // constructor.
     ExprResult NewDefArg;
     if (OldParam->hasDefaultArg()) {
-      NewDefArg = Args.getNumLevels()
-                      ? SemaRef.SubstExpr(OldParam->getDefaultArg(), Args)
-                      : OldParam->getDefaultArg();
+      NewDefArg = SemaRef.SubstExpr(OldParam->getDefaultArg(), Args);
       if (NewDefArg.isInvalid())
         return nullptr;
     }
@@ -1929,6 +1938,7 @@ private:
                                                 NewDefArg.get());
     NewParam->setScopeInfo(OldParam->getFunctionScopeDepth(),
                            OldParam->getFunctionScopeIndex());
+    SemaRef.CurrentInstantiationScope->InstantiatedLocal(OldParam, NewParam);
     return NewParam;
   }
 

diff --git a/test/SemaCXX/cxx1z-class-template-argument-deduction.cpp b/test/SemaCXX/cxx1z-class-template-argument-deduction.cpp
index f72cb886d81ad6f1089b6136ec5beb9ff2d29845..cbf7c2eee51cdef578c1bf6c43c755f286190d68 100644 (file)
--- a/test/SemaCXX/cxx1z-class-template-argument-deduction.cpp
+++ b/test/SemaCXX/cxx1z-class-template-argument-deduction.cpp
@@ -373,6 +373,35 @@ void bar(D<int>& d) {
 }
 }
 
+namespace rdar41330135 {
+template <int> struct A {};
+template <class T>
+struct S {
+  template <class U>
+  S(T a, U t, A<sizeof(t)>);
+};
+template <class T> struct D {
+  D(T t, A<sizeof(t)>);
+};
+int f() {
+  S s(0, 0, A<sizeof(int)>());
+  D d(0, A<sizeof(int)>());
+}
+
+namespace test_dupls {
+template<unsigned long> struct X {};
+template<typename T> struct A {
+  A(T t, X<sizeof(t)>);
+};
+A a(0, {});
+template<typename U> struct B {
+  B(U u, X<sizeof(u)>);
+};
+B b(0, {});
+}
+
+}
+
 #else
 
 // expected-no-diagnostics