Represent C++ direct initializers as ParenListExprs before semantic analysis

instead of having a special-purpose function.

- ActOnCXXDirectInitializer, which was mostly duplication of
  AddInitializerToDecl (leading e.g. to PR10620, which Eli fixed a few days
  ago), is dropped completely.
- MultiInitializer, which was an ugly hack I added, is dropped again.
- We now have the infrastructure in place to distinguish between
  int x = {1};
  int x({1});
  int x{1};
-- VarDecl now has getInitStyle(), which indicates which of the above was used.
-- CXXConstructExpr now has a flag to indicate that it represents list-
   initialization, although this is not yet used.
- InstantiateInitializer was renamed to SubstInitializer and simplified.
- ActOnParenOrParenListExpr has been replaced by ActOnParenListExpr, which
  always produces a ParenListExpr. Placed that so far failed to convert that
  back to a ParenExpr containing comma operators have been fixed. I'm pretty
  sure I could have made a crashing test case before this.

The end result is a (I hope) considerably cleaner design of initializers.
More importantly, the fact that I can now distinguish between the various
initialization kinds means that I can get the tricky generalized initializer
test cases Johannes Schaub supplied to work. (This is not yet done.)

This commit passed self-host, with the resulting compiler passing the tests. I
hope it doesn't break more complicated code. It's a pretty big change, but one
that I feel is necessary.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@150318 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 87 insertions, 35 deletions

diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 6ba3228b08..feffaf13fa 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -2139,9 +2139,8 @@ void Sema::mergeObjCMethodDecls(ObjCMethodDecl *newMethod,
 /// emitting diagnostics as appropriate.
 ///
 /// Declarations using the auto type specifier (C++ [decl.spec.auto]) call back
-/// to here in AddInitializerToDecl and AddCXXDirectInitializerToDecl. We can't
-/// check them before the initializer is attached.
-///
+/// to here in AddInitializerToDecl. We can't check them before the initializer
+/// is attached.
 void Sema::MergeVarDeclTypes(VarDecl *New, VarDecl *Old) {
   if (New->isInvalidDecl() || Old->isInvalidDecl())
     return;
@@ -5983,17 +5982,6 @@ void Sema::AddInitializerToDecl(Decl *RealDecl, Expr *Init,
   if (RealDecl == 0 || RealDecl->isInvalidDecl())
     return;
 
-  // Check for self-references within variable initializers.
-  if (VarDecl *vd = dyn_cast<VarDecl>(RealDecl)) {
-    // Variables declared within a function/method body are handled
-    // by a dataflow analysis.
-    if (!vd->hasLocalStorage() && !vd->isStaticLocal())
-      CheckSelfReference(RealDecl, Init);    
-  }
-  else {
-    CheckSelfReference(RealDecl, Init);
-  }
-
   if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(RealDecl)) {
     // With declarators parsed the way they are, the parser cannot
     // distinguish between a normal initializer and a pure-specifier.
@@ -6018,12 +6006,44 @@ void Sema::AddInitializerToDecl(Decl *RealDecl, Expr *Init,
     return;
   }
 
+  // Check for self-references within variable initializers.
+  // Variables declared within a function/method body are handled
+  // by a dataflow analysis.
+  if (!VDecl->hasLocalStorage() && !VDecl->isStaticLocal())
+    CheckSelfReference(RealDecl, Init);
+
+  ParenListExpr *CXXDirectInit = dyn_cast<ParenListExpr>(Init);
+
   // C++11 [decl.spec.auto]p6. Deduce the type which 'auto' stands in for.
   if (TypeMayContainAuto && VDecl->getType()->getContainedAutoType()) {
+    Expr *DeduceInit = Init;
+    // Initializer could be a C++ direct-initializer. Deduction only works if it
+    // contains exactly one expression.
+    if (CXXDirectInit) {
+      if (CXXDirectInit->getNumExprs() == 0) {
+        // It isn't possible to write this directly, but it is possible to
+        // end up in this situation with "auto x(some_pack...);"
+        Diag(CXXDirectInit->getSourceRange().getBegin(),
+             diag::err_auto_var_init_no_expression)
+          << VDecl->getDeclName() << VDecl->getType()
+          << VDecl->getSourceRange();
+        RealDecl->setInvalidDecl();
+        return;
+      } else if (CXXDirectInit->getNumExprs() > 1) {
+        Diag(CXXDirectInit->getExpr(1)->getSourceRange().getBegin(),
+             diag::err_auto_var_init_multiple_expressions)
+          << VDecl->getDeclName() << VDecl->getType()
+          << VDecl->getSourceRange();
+        RealDecl->setInvalidDecl();
+        return;
+      } else {
+        DeduceInit = CXXDirectInit->getExpr(0);
+      }
+    }
     TypeSourceInfo *DeducedType = 0;
-    if (DeduceAutoType(VDecl->getTypeSourceInfo(), Init, DeducedType) ==
+    if (DeduceAutoType(VDecl->getTypeSourceInfo(), DeduceInit, DeducedType) ==
             DAR_Failed)
-      DiagnoseAutoDeductionFailure(VDecl, Init);
+      DiagnoseAutoDeductionFailure(VDecl, DeduceInit);
     if (!DeducedType) {
       RealDecl->setInvalidDecl();
       return;
@@ -6048,25 +6068,26 @@ void Sema::AddInitializerToDecl(Decl *RealDecl, Expr *Init,
     return;
   }
 
+  if (!VDecl->getType()->isDependentType()) {
+    // A definition must end up with a complete type, which means it must be
+    // complete with the restriction that an array type might be completed by
+    // the initializer; note that later code assumes this restriction.
+    QualType BaseDeclType = VDecl->getType();
+    if (const ArrayType *Array = Context.getAsIncompleteArrayType(BaseDeclType))
+      BaseDeclType = Array->getElementType();
+    if (RequireCompleteType(VDecl->getLocation(), BaseDeclType,
+                            diag::err_typecheck_decl_incomplete_type)) {
+      RealDecl->setInvalidDecl();
+      return;
+    }
 
-  // A definition must end up with a complete type, which means it must be
-  // complete with the restriction that an array type might be completed by the
-  // initializer; note that later code assumes this restriction.
-  QualType BaseDeclType = VDecl->getType();
-  if (const ArrayType *Array = Context.getAsIncompleteArrayType(BaseDeclType))
-    BaseDeclType = Array->getElementType();
-  if (RequireCompleteType(VDecl->getLocation(), BaseDeclType,
-                          diag::err_typecheck_decl_incomplete_type)) {
-    RealDecl->setInvalidDecl();
-    return;
+    // The variable can not have an abstract class type.
+    if (RequireNonAbstractType(VDecl->getLocation(), VDecl->getType(),
+                               diag::err_abstract_type_in_decl,
+                               AbstractVariableType))
+      VDecl->setInvalidDecl();
   }
 
-  // The variable can not have an abstract class type.
-  if (RequireNonAbstractType(VDecl->getLocation(), VDecl->getType(),
-                             diag::err_abstract_type_in_decl,
-                             AbstractVariableType))
-    VDecl->setInvalidDecl();
-
   const VarDecl *Def;
   if ((Def = VDecl->getDefinition()) && Def != VDecl) {
     Diag(VDecl->getLocation(), diag::err_redefinition)
@@ -6128,9 +6149,15 @@ void Sema::AddInitializerToDecl(Decl *RealDecl, Expr *Init,
                    : InitializationKind::CreateCopy(VDecl->getLocation(),
                                                     Init->getLocStart());
 
-    InitializationSequence InitSeq(*this, Entity, Kind, &Init, 1);
+    Expr **Args = &Init;
+    unsigned NumArgs = 1;
+    if (CXXDirectInit) {
+      Args = CXXDirectInit->getExprs();
+      NumArgs = CXXDirectInit->getNumExprs();
+    }
+    InitializationSequence InitSeq(*this, Entity, Kind, Args, NumArgs);
     ExprResult Result = InitSeq.Perform(*this, Entity, Kind,
-                                              MultiExprArg(*this, &Init, 1),
+                                              MultiExprArg(*this, Args,NumArgs),
                                               &DclT);
     if (Result.isInvalid()) {
       VDecl->setInvalidDecl();
@@ -6266,6 +6293,28 @@ void Sema::AddInitializerToDecl(Decl *RealDecl, Expr *Init,
       CheckForConstantInitializer(Init, DclT);
   }
 
+  // We will represent direct-initialization similarly to copy-initialization:
+  //    int x(1);  -as-> int x = 1;
+  //    ClassType x(a,b,c); -as-> ClassType x = ClassType(a,b,c);
+  //
+  // Clients that want to distinguish between the two forms, can check for
+  // direct initializer using VarDecl::getInitStyle().
+  // A major benefit is that clients that don't particularly care about which
+  // exactly form was it (like the CodeGen) can handle both cases without
+  // special case code.
+
+  // C++ 8.5p11:
+  // The form of initialization (using parentheses or '=') is generally
+  // insignificant, but does matter when the entity being initialized has a
+  // class type.
+  if (CXXDirectInit) {
+    assert(DirectInit && "Call-style initializer must be direct init.");
+    VDecl->setInitStyle(VarDecl::CallInit);
+  } else if (DirectInit) {
+    // This must be list-initialization. No other way is direct-initialization.
+    VDecl->setInitStyle(VarDecl::ListInit);
+  }
+
   CheckCompleteVariableDeclaration(VDecl);
 }
 
@@ -6496,8 +6545,11 @@ void Sema::ActOnUninitializedDecl(Decl *RealDecl,
                                       MultiExprArg(*this, 0, 0));
     if (Init.isInvalid())
       Var->setInvalidDecl();
-    else if (Init.get())
+    else if (Init.get()) {
       Var->setInit(MaybeCreateExprWithCleanups(Init.get()));
+      // This is important for template substitution.
+      Var->setInitStyle(VarDecl::CallInit);
+    }
 
     CheckCompleteVariableDeclaration(Var);
   }