[c++1z] Require an initializer for deduced class template specialization types.

It's actually meaningful and useful to allow such variables to have no
initializer, but we are strictly following the standard here until the C++
committee reaches consensus on allowing this.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@294785 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td
index 6bf33897d5d590eee8f22456e555c1d2f7938e76..e64fed77edd11b747550a08bfd5c1315d3f9915a 100644 (file)
--- a/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/include/clang/Basic/DiagnosticSemaKinds.td
@@ -1893,7 +1893,7 @@ def err_dependent_deduced_tst : Error<
 def err_auto_not_allowed_var_inst : Error<
   "'auto' variable template instantiation is not allowed">;
 def err_auto_var_requires_init : Error<
-  "declaration of variable %0 with type %1 requires an initializer">;
+  "declaration of variable %0 with deduced type %1 requires an initializer">;
 def err_auto_new_requires_ctor_arg : Error<
   "new expression for type %0 requires a constructor argument">;
 def err_auto_new_list_init : Error<

diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 2a082fc775b7fd6234a0f3cd8694ab2be6cff350..17d58b156bab186385acf20351cea1cbc7b8b036 100644 (file)
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -9816,7 +9816,15 @@ QualType Sema::deduceVarTypeFromInitializer(VarDecl *VDecl,
   DeducedType *Deduced = Type->getContainedDeducedType();
   assert(Deduced && "deduceVarTypeFromInitializer for non-deduced type");
 
-  ArrayRef<Expr*> DeduceInits = Init ? ArrayRef<Expr*>(Init) : None;
+  // 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_or_null<ParenListExpr>(Init))
       DeduceInits = PL->exprs();
@@ -9833,14 +9841,6 @@ QualType Sema::deduceVarTypeFromInitializer(VarDecl *VDecl,
                                                        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();
-  }
-
   if (DirectInit) {
     if (auto *IL = dyn_cast<InitListExpr>(Init))
       DeduceInits = IL->inits();

diff --git a/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.spec.auto/p3-1y.cpp b/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.spec.auto/p3-1y.cpp
index eb751517e2f2a206abc3aa6309b83c958b5d02ea..fce5795daecb117f8428751998992e474d6b1700 100644 (file)
--- a/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.spec.auto/p3-1y.cpp
+++ b/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.spec.auto/p3-1y.cpp
@@ -9,9 +9,9 @@ void f() {
 }
 
 void g() {
-  decltype(auto) a; // expected-error{{declaration of variable 'a' with type 'decltype(auto)' requires an initializer}}
+  decltype(auto) a; // expected-error{{declaration of variable 'a' with deduced type 'decltype(auto)' requires an initializer}}
   
-  decltype(auto) *b; // expected-error{{cannot form pointer to 'decltype(auto)'}} expected-error{{declaration of variable 'b' with type 'decltype(auto) *' requires an initializer}}
+  decltype(auto) *b; // expected-error{{cannot form pointer to 'decltype(auto)'}} expected-error{{declaration of variable 'b' with deduced type 'decltype(auto) *' requires an initializer}}
 
   if (decltype(auto) b) {} // expected-error {{must have an initializer}}
   for (;decltype(auto) b;) {} // expected-error {{must have an initializer}}

diff --git a/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.spec.auto/p3.cpp b/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.spec.auto/p3.cpp
index e91cacf10466ca7eef587952c4d4ed21b8996be1..c38bd7a84d4711fdeeed504a79d1a7e70dfeb96f 100644 (file)
--- a/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.spec.auto/p3.cpp
+++ b/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.spec.auto/p3.cpp
@@ -9,9 +9,9 @@ void f() {
 }
 
 void g() {
-  auto a; // expected-error{{declaration of variable 'a' with type 'auto' requires an initializer}}
+  auto a; // expected-error{{declaration of variable 'a' with deduced type 'auto' requires an initializer}}
   
-  auto *b; // expected-error{{declaration of variable 'b' with type 'auto *' requires an initializer}}
+  auto *b; // expected-error{{declaration of variable 'b' with deduced type 'auto *' requires an initializer}}
 
   if (auto b) {} // expected-error {{must have an initializer}}
   for (;auto b;) {} // expected-error {{must have an initializer}}

diff --git a/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.spec.auto/p4.cpp b/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.spec.auto/p4.cpp
index 46c874f605cbf27d6c64f23fdd2a4612c003ca42..bf1b3092e08e86a2443c324769dd38a706cc2ac4 100644 (file)
--- a/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.spec.auto/p4.cpp
+++ b/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.spec.auto/p4.cpp
@@ -36,7 +36,7 @@ class X {
 };
 
 struct S {
-  static const auto a; // expected-error {{declaration of variable 'a' with type 'const auto' requires an initializer}}
+  static const auto a; // expected-error {{declaration of variable 'a' with deduced type 'const auto' requires an initializer}}
   static const auto b = 0;
   static const int c;
 };

diff --git a/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.type.class.deduct/p1.cpp b/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.type.class.deduct/p1.cpp
index 88197999cd9054f938940b66bf0d0afe5daefb3b..cfb9a61f1ac42b5155d8fe9e15e80560f89bdfcf 100644 (file)
--- a/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.type.class.deduct/p1.cpp
+++ b/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.type.class.deduct/p1.cpp
@@ -5,8 +5,14 @@ A() -> A<int>;
 A(int) -> A<char>;
 
 static constexpr inline const volatile A a = {}; // ok, specifiers are permitted
-A b; // FIXME: An initializer is required
+// FIXME: There isn't really a good reason to reject this.
+A b; // expected-error {{requires an initializer}}
 A c [[]] {};
 
 A d = {}, e = {};
 A f(0), g{}; // expected-error {{template arguments deduced as 'A<char>' in declaration of 'f' and deduced as 'A<int>' in declaration of 'g'}}
+
+struct B {
+  static A a; // expected-error {{requires an initializer}}
+};
+extern A x; // expected-error {{requires an initializer}}

diff --git a/test/Parser/cxx1z-class-template-argument-deduction.cpp b/test/Parser/cxx1z-class-template-argument-deduction.cpp
index 10be123eb05524f86eb18f6b1b01818c395d3c8f..ab8c867f60a040fae6eecf4d0c287620098c5eee 100644 (file)
--- a/test/Parser/cxx1z-class-template-argument-deduction.cpp
+++ b/test/Parser/cxx1z-class-template-argument-deduction.cpp
@@ -52,7 +52,7 @@ struct member {
 
   operator A(); // expected-error {{requires template arguments; argument deduction not allowed in conversion function type}}
 
-  static A x; // FIXME: We deduce A<int> from the initializer despite this not being a definition!
+  static A x; // expected-error {{declaration of variable 'x' with deduced type 'A' requires an initializer}}
   static constexpr A y = 0;
 };
 
@@ -127,7 +127,7 @@ namespace decl {
 
   auto k() -> A; // expected-error{{requires template arguments}}
 
-  A a; // FIXME: This is (technically) syntactically invalid.
+  A a; // expected-error {{declaration of variable 'a' with deduced type 'A' requires an initializer}}
   A b = 0;
   const A c = 0;
   A (parens) = 0; // expected-error {{cannot use parentheses when declaring variable with deduced class template specialization type}}

diff --git a/test/SemaCXX/cxx1y-variable-templates_top_level.cpp b/test/SemaCXX/cxx1y-variable-templates_top_level.cpp
index 367f67bf5fa8f04c11eda0cc22c7278b037aa0a8..b4963646838cb607895add56e69cb3367d3138d2 100644 (file)
--- a/test/SemaCXX/cxx1y-variable-templates_top_level.cpp
+++ b/test/SemaCXX/cxx1y-variable-templates_top_level.cpp
@@ -102,7 +102,7 @@ namespace odr_tmpl {
     template<typename T> extern int v;    // expected-error {{redeclaration of 'v' with a different type: 'int' vs 'T'}}
 
 #ifndef PRECXX11
-    template<typename T> extern auto v;   // expected-error {{declaration of variable 'v' with type 'auto' requires an initializer}}
+    template<typename T> extern auto v;   // expected-error {{declaration of variable 'v' with deduced type 'auto' requires an initializer}}
 #endif
 
     template<typename T> T var = T();     // expected-note {{previous definition is here}}
@@ -111,7 +111,7 @@ namespace odr_tmpl {
 
 #ifndef PRECXX11
   namespace pvt_auto {
-    template<typename T> auto v0; // expected-error {{declaration of variable 'v0' with type 'auto' requires an initializer}}
+    template<typename T> auto v0; // expected-error {{declaration of variable 'v0' with deduced type 'auto' requires an initializer}}
     template<typename T> auto v1 = T();  // expected-note {{previous definition is here}}
     template<typename T> int v1;   // expected-error {{redefinition of 'v1' with a different type: 'int' vs 'auto'}}
     template<typename T> auto v2 = T();  // expected-note {{previous definition is here}}
@@ -119,7 +119,7 @@ namespace odr_tmpl {
     template<typename T> auto v3 = T();   // expected-note {{previous definition is here}}
     template<typename T> extern T v3;     // expected-error {{redeclaration of 'v3' with a different type: 'T' vs 'auto'}}
     template<typename T> auto v4 = T();
-    template<typename T> extern auto v4;   // expected-error {{declaration of variable 'v4' with type 'auto' requires an initializer}}
+    template<typename T> extern auto v4;   // expected-error {{declaration of variable 'v4' with deduced type 'auto' requires an initializer}}
   }
 #endif