re PR c++/45923 (constexpr diagnostics, more more)

	PR c++/45923
	* class.c (explain_non_literal_class): New.
	(finalize_literal_type_property): Call it.
	* cp-tree.h: Declare it.
	* semantics.c (ensure_literal_type_for_constexpr_object): Call it.
	(is_valid_constexpr_fn): Likewise.
	(massage_constexpr_body): Split out from...
	(register_constexpr_fundef): ...here.
	(is_instantiation_of_constexpr): New.
	(expand_or_defer_fn_1): Leave DECL_SAVED_TREE alone in that case.
	(explain_invalid_constexpr_fn): New.
	(cxx_eval_call_expression): Call it.
	(potential_constant_expression_1): Likewise.  Avoid redundant errors.
	* method.c (process_subob_fn): Diagnose non-constexpr.
	(walk_field_subobs): Likewise.
	(synthesized_method_walk): Don't shortcut if we want diagnostics.
	(explain_implicit_non_constexpr): New.
	(defaulted_late_check): Use it.
	* call.c (build_cxx_call): Remember location.

From-SVN: r175646

5 files changed, 59 insertions, 5 deletions

diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-diag1.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-diag1.C
index 183d3f768fa..44e6bc7e089 100644
--- a/gcc/testsuite/g++.dg/cpp0x/constexpr-diag1.C
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-diag1.C
@@ -13,7 +13,7 @@ struct B { B(); operator int(); };
 constexpr A<int> ai = { 42 };
 constexpr int i = ai.f();
 
-constexpr int b = A<B>().f();	// { dg-error "not a constexpr function" }
+constexpr int b = A<B>().f();	// { dg-error "non-constexpr function" }
 
 template <class T>
 constexpr int f (T t) { return 42; } // { dg-error "parameter" }
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-diag3.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-diag3.C
new file mode 100644
index 00000000000..100c17edb45
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-diag3.C
@@ -0,0 +1,54 @@
+// PR c++/45923
+// { dg-options -std=c++0x }
+
+int f(int);
+
+template <class T>
+constexpr T g(T t) { return f(t); } // { dg-error "f.int" }
+
+int main()
+{
+  constexpr int i = g(1);	// { dg-error "g.T" }
+}
+
+// --------------------
+
+struct complex 			// { dg-message "no constexpr constructor" }
+{
+  complex(double r, double i) : re(r), im(i) { }
+  constexpr double real() { return re; } // { dg-error "not a literal type" }
+  double imag() const { return im; }
+
+private:
+  double re;
+  double im;
+};
+
+constexpr complex co1(0, 1);	   // { dg-error "not literal" }
+constexpr double dd2 = co1.real(); // { dg-error "non-constexpr function" }
+
+// --------------------
+
+struct base		       // { dg-message "no constexpr constructor" }
+{
+  int _M_i;
+  base() : _M_i(5) { }
+};
+
+struct derived : public base	// { dg-message "base class" }
+{
+  constexpr derived(): base() { } // { dg-error "non-constexpr function" }
+};
+
+constexpr derived obj;		// { dg-error "not literal" }
+
+// --------------------
+
+struct Def
+{
+  int _M_i;			// { dg-message "does not initialize" }
+
+  constexpr Def() = default;	// { dg-error "implicit declaration is not constexpr" }
+};
+
+constexpr Def defobj;		// { dg-error "uninitialized" }
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-ex1.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-ex1.C
index 4ab4677805f..584a5a09b69 100644
--- a/gcc/testsuite/g++.dg/cpp0x/constexpr-ex1.C
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-ex1.C
@@ -88,7 +88,7 @@ struct resource {
   }
 };
 constexpr resource f(resource d)
-{ return d; }                  // { dg-error "not .constexpr" }
+{ return d; }                  // { dg-error "non-constexpr" }
 constexpr resource d = f(9);   // { dg-error "resource" }
 
 // 4.4 floating-point constant expressions
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-friend.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-friend.C
index f1d9ccee790..1831a2b003c 100644
--- a/gcc/testsuite/g++.dg/cpp0x/constexpr-friend.C
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-friend.C
@@ -19,5 +19,5 @@ struct C
 
 constexpr int i = f(C<int>());
 constexpr int j = C<int>().m(C<int>());
-constexpr int k = C<double>().m(A()); // { dg-error "not a constexpr function" }
-constexpr int l = g(C<double>(),A()); // { dg-error "not a constexpr function" }
+constexpr int k = C<double>().m(A()); // { dg-error "non-constexpr function" }
+constexpr int l = g(C<double>(),A()); // { dg-error "non-constexpr function" }
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-incomplete2.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-incomplete2.C
index dc0b7429dc6..f61535f06be 100644
--- a/gcc/testsuite/g++.dg/cpp0x/constexpr-incomplete2.C
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-incomplete2.C
@@ -28,4 +28,4 @@ struct D
   C<D> c;
 };
 
-constexpr D d {};		// { dg-error "not a constexpr function" }
+constexpr D d {};		// { dg-error "non-constexpr function" }