Auto deduction support for std::initializer_list, including for-range support. This means you can now write:

for (int i : {1, 4, 512, 23, 251}) {}

llvm-svn: 148353

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -1196,10 +1196,17 @@ def err_trailing_return_in_parens : Error<
   "trailing return type may not be nested within parentheses">;
 def err_auto_var_deduction_failure : Error<
   "variable %0 with type %1 has incompatible initializer of type %2">;
+def err_auto_var_deduction_failure_from_init_list : Error<
+  "cannot deduce actual type for variable %0 with type %1 from initializer list">;
 def err_auto_new_deduction_failure : Error<
   "new expression for type %0 has incompatible constructor argument of type %1">;
 def err_auto_different_deductions : Error<
   "'auto' deduced as %0 in declaration of %1 and deduced as %2 in declaration of %3">;
+def err_implied_std_initializer_list_not_found : Error<
+  "cannot deduce type of initializer list because std::initializer_list was "
+  "not found; include <initializer_list>">;
+def err_malformed_std_initializer_list : Error<
+  "std::initializer_list must be a class template with a single type parameter">;
 
 // C++11 override control
 def override_keyword_only_allowed_on_virtual_member_functions : Error<

clang/include/clang/Sema/Sema.h

@@ -2729,6 +2729,12 @@ public:
   /// it is and Element is not NULL, assigns the element type to Element.
   bool isStdInitializerList(QualType Ty, QualType *Element);
 
+  /// \brief Looks for the std::initializer_list template and instantiates it
+  /// with Element, or emits an error if it's not found.
+  ///
+  /// \returns The instantiated template, or null on error.
+  QualType BuildStdInitializerList(QualType Element, SourceLocation Loc);
+
   Decl *ActOnUsingDirective(Scope *CurScope,
                             SourceLocation UsingLoc,
                             SourceLocation NamespcLoc,
@@ -4707,6 +4713,7 @@ public:
 
   bool DeduceAutoType(TypeSourceInfo *AutoType, Expr *&Initializer,
                       TypeSourceInfo *&Result);
+  void DiagnoseAutoDeductionFailure(VarDecl *VDecl, Expr *Init);
 
   FunctionTemplateDecl *getMoreSpecializedTemplate(FunctionTemplateDecl *FT1,
                                                    FunctionTemplateDecl *FT2,

clang/lib/Sema/SemaDecl.cpp

@@ -5976,9 +5976,7 @@ void Sema::AddInitializerToDecl(Decl *RealDecl, Expr *Init,
   if (TypeMayContainAuto && VDecl->getType()->getContainedAutoType()) {
     TypeSourceInfo *DeducedType = 0;
     if (!DeduceAutoType(VDecl->getTypeSourceInfo(), Init, DeducedType))
-      Diag(VDecl->getLocation(), diag::err_auto_var_deduction_failure)
+      DiagnoseAutoDeductionFailure(VDecl, Init);
-        << VDecl->getDeclName() << VDecl->getType() << Init->getType()
-        << Init->getSourceRange();
     if (!DeducedType) {
       RealDecl->setInvalidDecl();
       return;

clang/lib/Sema/SemaDeclCXX.cpp

@@ -5829,6 +5829,54 @@ bool Sema::isStdInitializerList(QualType Ty, QualType *Element) {
   return true;
 }
 
+static ClassTemplateDecl *LookupStdInitializerList(Sema &S, SourceLocation Loc){
+  NamespaceDecl *Std = S.getStdNamespace();
+  if (!Std) {
+    S.Diag(Loc, diag::err_implied_std_initializer_list_not_found);
+    return 0;
+  }
+
+  LookupResult Result(S, &S.PP.getIdentifierTable().get("initializer_list"),
+                      Loc, Sema::LookupOrdinaryName);
+  if (!S.LookupQualifiedName(Result, Std)) {
+    S.Diag(Loc, diag::err_implied_std_initializer_list_not_found);
+    return 0;
+  }
+  ClassTemplateDecl *Template = Result.getAsSingle<ClassTemplateDecl>();
+  if (!Template) {
+    Result.suppressDiagnostics();
+    // We found something weird. Complain about the first thing we found.
+    NamedDecl *Found = *Result.begin();
+    S.Diag(Found->getLocation(), diag::err_malformed_std_initializer_list);
+    return 0;
+  }
+
+  // We found some template called std::initializer_list. Now verify that it's
+  // correct.
+  TemplateParameterList *Params = Template->getTemplateParameters();
+  if (Params->size() != 1 || !isa<TemplateTypeParmDecl>(Params->getParam(0))) {
+    S.Diag(Template->getLocation(), diag::err_malformed_std_initializer_list);
+    return 0;
+  }
+
+  return Template;
+}
+
+QualType Sema::BuildStdInitializerList(QualType Element, SourceLocation Loc) {
+  if (!StdInitializerList) {
+    StdInitializerList = LookupStdInitializerList(*this, Loc);
+    if (!StdInitializerList)
+      return QualType();
+  }
+
+  TemplateArgumentListInfo Args(Loc, Loc);
+  Args.addArgument(TemplateArgumentLoc(TemplateArgument(Element),
+                                       Context.getTrivialTypeSourceInfo(Element,
+                                                                        Loc)));
+  return Context.getCanonicalType(
+      CheckTemplateIdType(TemplateName(StdInitializerList), Loc, Args));
+}
+
 /// \brief Determine whether a using statement is in a context where it will be
 /// apply in all contexts.
 static bool IsUsingDirectiveInToplevelContext(DeclContext *CurContext) {
@@ -9027,9 +9075,7 @@ void Sema::AddCXXDirectInitializerToDecl(Decl *RealDecl,
     Expr *Init = Exprs.get()[0];
     TypeSourceInfo *DeducedType = 0;
     if (!DeduceAutoType(VDecl->getTypeSourceInfo(), Init, DeducedType))
-      Diag(VDecl->getLocation(), diag::err_auto_var_deduction_failure)
+      DiagnoseAutoDeductionFailure(VDecl, Init);
-        << VDecl->getDeclName() << VDecl->getType() << Init->getType()
-        << Init->getSourceRange();
     if (!DeducedType) {
       RealDecl->setInvalidDecl();
       return;

clang/lib/Sema/SemaStmt.cpp

@@ -1164,7 +1164,7 @@ static bool FinishForRangeVarDecl(Sema &SemaRef, VarDecl *Decl, Expr *Init,
   // Deduce the type for the iterator variable now rather than leaving it to
   // AddInitializerToDecl, so we can produce a more suitable diagnostic.
   TypeSourceInfo *InitTSI = 0;
-  if (Init->getType()->isVoidType() ||
+  if ((!isa<InitListExpr>(Init) && Init->getType()->isVoidType()) ||
       !SemaRef.DeduceAutoType(Decl->getTypeSourceInfo(), Init, InitTSI))
     SemaRef.Diag(Loc, diag) << Init->getType();
   if (!InitTSI) {

clang/lib/Sema/SemaTemplateDeduction.cpp

@@ -3422,19 +3422,36 @@ Sema::DeduceAutoType(TypeSourceInfo *Type, Expr *&Init,
     return false;
 
   TemplateDeductionInfo Info(Context, Loc);
-  if (DeduceTemplateArgumentsByTypeMatch(*this, &TemplateParams, FuncParam,
+
-                                         InitType, Info, Deduced, TDF))
+  InitListExpr * InitList = dyn_cast<InitListExpr>(Init);
-    return false;
+  if (InitList) {
+    for (unsigned i = 0, e = InitList->getNumInits(); i < e; ++i) {
+      if (DeduceTemplateArgumentsByTypeMatch(*this, &TemplateParams, FuncParam,
+                                             InitList->getInit(i)->getType(),
+                                             Info, Deduced, TDF))
+        return false;
+    }
+  } else {
+    if (DeduceTemplateArgumentsByTypeMatch(*this, &TemplateParams, FuncParam,
+                                           InitType, Info, Deduced, TDF))
+      return false;
+  }
 
   QualType DeducedType = Deduced[0].getAsType();
   if (DeducedType.isNull())
     return false;
 
+  if (InitList) {
+    DeducedType = BuildStdInitializerList(DeducedType, Loc);
+    if (DeducedType.isNull())
+      return false;
+  }
+
   Result = SubstituteAutoTransform(*this, DeducedType).TransformType(Type);
 
   // Check that the deduced argument type is compatible with the original
   // argument type per C++ [temp.deduct.call]p4.
-  if (Result &&
+  if (!InitList && Result &&
       CheckOriginalCallArgDeduction(*this, 
                                     Sema::OriginalCallArg(FuncParam,0,InitType),
                                     Result->getType())) {
@@ -3445,6 +3462,17 @@ Sema::DeduceAutoType(TypeSourceInfo *Type, Expr *&Init,
   return true;
 }
 
+void Sema::DiagnoseAutoDeductionFailure(VarDecl *VDecl, Expr *Init) {
+  if (isa<InitListExpr>(Init))
+    Diag(VDecl->getLocation(),
+         diag::err_auto_var_deduction_failure_from_init_list)
+      << VDecl->getDeclName() << VDecl->getType() << Init->getSourceRange();
+  else
+    Diag(VDecl->getLocation(), diag::err_auto_var_deduction_failure)
+      << VDecl->getDeclName() << VDecl->getType() << Init->getType()
+      << Init->getSourceRange();
+}
+
 static void
 MarkUsedTemplateParameters(ASTContext &Ctx, QualType T,
                            bool OnlyDeduced,

clang/test/SemaCXX/cxx0x-initializer-stdinitializerlist.cpp

@@ -109,3 +109,11 @@ void argument_deduction() {
 
   deduce_ref({1, 2.0}); // expected-error {{no matching function}}
 }
+
+void auto_deduction() {
+  auto l = {1, 2, 3, 4};
+  static_assert(same_type<decltype(l), std::initializer_list<int>>::value, "");
+  auto bl = {1, 2.0}; // expected-error {{cannot deduce}}
+
+  for (int i : {1, 2, 3, 4}) {}
+}

clang/test/SemaCXX/generalized-initializers.cpp

@@ -38,18 +38,6 @@ namespace std {
   };
 }
 
-namespace integral {
-
-  void initializer_list() {
-    auto l = {1, 2, 3, 4};
-    static_assert(same_type<decltype(l), std::initializer_list<int>>::value, "");
-    auto bl = {1, 2.0}; // expected-error {{cannot deduce}}
-
-    for (int i : {1, 2, 3, 4}) {}
-  }
-
-}
-
 namespace objects {
 
   struct X1 { X1(int); };