[c++1z] P0091R3: Basic support for deducing class template arguments via deduction-guides.

llvm-svn: 294613

1 files changed, 57 insertions, 46 deletions

diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index f103f30b4df..658146d6389 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -9807,16 +9807,33 @@ QualType Sema::deduceVarTypeFromInitializer(VarDecl *VDecl,
   DeducedType *Deduced = Type->getContainedDeducedType();
   assert(Deduced && "deduceVarTypeFromInitializer for non-deduced type");
 
+  ArrayRef<Expr*> DeduceInits = Init ? ArrayRef<Expr*>(Init) : None;
+  if (DirectInit) {
+    if (auto *PL = dyn_cast_or_null<ParenListExpr>(Init))
+      DeduceInits = PL->exprs();
+  }
+
   if (isa<DeducedTemplateSpecializationType>(Deduced)) {
-    Diag(Init->getLocStart(), diag::err_deduced_class_template_not_supported);
+    assert(VDecl && "non-auto type for init capture deduction?");
+    InitializedEntity Entity = InitializedEntity::InitializeVariable(VDecl);
+    InitializationKind Kind = InitializationKind::CreateForInit(
+        VDecl->getLocation(), DirectInit, Init);
+    // FIXME: Initialization should not be taking a mutable list of inits. 
+    SmallVector<Expr*, 8> InitsCopy(DeduceInits.begin(), DeduceInits.end());
+    return DeduceTemplateSpecializationFromInitializer(TSI, Entity, Kind,
+                                                       InitsCopy);
+  }
+
+  // C++11 [dcl.spec.auto]p3
+  if (!Init) {
+    assert(VDecl && "no init for init capture deduction?");
+    Diag(VDecl->getLocation(), diag::err_auto_var_requires_init)
+      << VDecl->getDeclName() << Type;
     return QualType();
   }
 
-  ArrayRef<Expr *> DeduceInits = Init;
   if (DirectInit) {
-    if (auto *PL = dyn_cast<ParenListExpr>(Init))
-      DeduceInits = PL->exprs();
-    else if (auto *IL = dyn_cast<InitListExpr>(Init))
+    if (auto *IL = dyn_cast<InitListExpr>(Init))
       DeduceInits = IL->inits();
   }
 
@@ -9902,6 +9919,36 @@ QualType Sema::deduceVarTypeFromInitializer(VarDecl *VDecl,
   return DeducedType;
 }
 
+bool Sema::DeduceVariableDeclarationType(VarDecl *VDecl, bool DirectInit,
+                                         Expr *Init) {
+  QualType DeducedType = deduceVarTypeFromInitializer(
+      VDecl, VDecl->getDeclName(), VDecl->getType(), VDecl->getTypeSourceInfo(),
+      VDecl->getSourceRange(), DirectInit, Init);
+  if (DeducedType.isNull()) {
+    VDecl->setInvalidDecl();
+    return true;
+  }
+
+  VDecl->setType(DeducedType);
+  assert(VDecl->isLinkageValid());
+
+  // In ARC, infer lifetime.
+  if (getLangOpts().ObjCAutoRefCount && inferObjCARCLifetime(VDecl))
+    VDecl->setInvalidDecl();
+
+  // If this is a redeclaration, check that the type we just deduced matches
+  // the previously declared type.
+  if (VarDecl *Old = VDecl->getPreviousDecl()) {
+    // We never need to merge the type, because we cannot form an incomplete
+    // array of auto, nor deduce such a type.
+    MergeVarDeclTypes(VDecl, Old, /*MergeTypeWithPrevious*/ false);
+  }
+
+  // Check the deduced type is valid for a variable declaration.
+  CheckVariableDeclarationType(VDecl);
+  return VDecl->isInvalidDecl();
+}
+
 /// AddInitializerToDecl - Adds the initializer Init to the
 /// declaration dcl. If DirectInit is true, this is C++ direct
 /// initialization rather than copy initialization.
@@ -9941,32 +9988,7 @@ void Sema::AddInitializerToDecl(Decl *RealDecl, Expr *Init, bool DirectInit) {
     }
     Init = Res.get();
 
-    QualType DeducedType = deduceVarTypeFromInitializer(
-        VDecl, VDecl->getDeclName(), VDecl->getType(),
-        VDecl->getTypeSourceInfo(), VDecl->getSourceRange(), DirectInit, Init);
-    if (DeducedType.isNull()) {
-      RealDecl->setInvalidDecl();
-      return;
-    }
-
-    VDecl->setType(DeducedType);
-    assert(VDecl->isLinkageValid());
-
-    // In ARC, infer lifetime.
-    if (getLangOpts().ObjCAutoRefCount && inferObjCARCLifetime(VDecl))
-      VDecl->setInvalidDecl();
-
-    // If this is a redeclaration, check that the type we just deduced matches
-    // the previously declared type.
-    if (VarDecl *Old = VDecl->getPreviousDecl()) {
-      // We never need to merge the type, because we cannot form an incomplete
-      // array of auto, nor deduce such a type.
-      MergeVarDeclTypes(VDecl, Old, /*MergeTypeWithPrevious*/ false);
-    }
-
-    // Check the deduced type is valid for a variable declaration.
-    CheckVariableDeclarationType(VDecl);
-    if (VDecl->isInvalidDecl())
+    if (DeduceVariableDeclarationType(VDecl, DirectInit, Init))
       return;
   }
 
@@ -10085,15 +10107,8 @@ void Sema::AddInitializerToDecl(Decl *RealDecl, Expr *Init, bool DirectInit) {
       }
 
     InitializedEntity Entity = InitializedEntity::InitializeVariable(VDecl);
-    InitializationKind Kind =
-        DirectInit
-            ? CXXDirectInit
-                  ? InitializationKind::CreateDirect(VDecl->getLocation(),
-                                                     Init->getLocStart(),
-                                                     Init->getLocEnd())
-                  : InitializationKind::CreateDirectList(VDecl->getLocation())
-            : InitializationKind::CreateCopy(VDecl->getLocation(),
-                                             Init->getLocStart());
+    InitializationKind Kind = InitializationKind::CreateForInit(
+        VDecl->getLocation(), DirectInit, Init);
 
     MultiExprArg Args = Init;
     if (CXXDirectInit)
@@ -10417,13 +10432,9 @@ void Sema::ActOnUninitializedDecl(Decl *RealDecl) {
       return;
     }
 
-    // C++11 [dcl.spec.auto]p3
-    if (Type->isUndeducedType()) {
-      Diag(Var->getLocation(), diag::err_auto_var_requires_init)
-        << Var->getDeclName() << Type;
-      Var->setInvalidDecl();
+    if (Type->isUndeducedType() &&
+        DeduceVariableDeclarationType(Var, false, nullptr))
       return;
-    }
 
     // C++11 [class.static.data]p3: A static data member can be declared with
     // the constexpr specifier; if so, its declaration shall specify