PR c++/88815 - narrowing conversion lost in decltype.

	PR c++/78244 - narrowing conversion in template not detected.
	* cp-tree.h (CONSTRUCTOR_IS_DEPENDENT): New.
	* pt.c (instantiation_dependent_r): Consider a CONSTRUCTOR with
	CONSTRUCTOR_IS_DEPENDENT instantiation-dependent.
	* semantics.c (finish_compound_literal): When the compound literal
	isn't instantiation-dependent and the type isn't type-dependent,
	fall back to the normal processing.  Set CONSTRUCTOR_IS_DEPENDENT.

	* g++.dg/cpp0x/Wnarrowing15.C: New test.
	* g++.dg/cpp0x/Wnarrowing16.C: New test.
	* g++.dg/cpp0x/constexpr-decltype3.C: New test.
	* g++.dg/cpp1y/Wnarrowing1.C: New test.

From-SVN: r268321

9 files changed, 91 insertions, 1 deletions

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index c2993db..dcac8e7 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,5 +1,14 @@
 2019-01-27  Marek Polacek  <polacek@redhat.com>
 
+	PR c++/88815 - narrowing conversion lost in decltype.
+	PR c++/78244 - narrowing conversion in template not detected.
+	* cp-tree.h (CONSTRUCTOR_IS_DEPENDENT): New.
+	* pt.c (instantiation_dependent_r): Consider a CONSTRUCTOR with
+	CONSTRUCTOR_IS_DEPENDENT instantiation-dependent.
+	* semantics.c (finish_compound_literal): When the compound literal
+	isn't instantiation-dependent and the type isn't type-dependent,
+	fall back to the normal processing.  Set CONSTRUCTOR_IS_DEPENDENT.
+
 	PR c++/89024 - ICE with incomplete enum type.
 	* call.c (standard_conversion): When converting an
 	ARITHMETIC_TYPE_P to an incomplete type, return NULL.
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index cd902ce..77e1425 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -424,6 +424,7 @@ extern GTY(()) tree cp_global_trees[CPTI_MAX];
       DECL_FINAL_P (in FUNCTION_DECL)
       QUALIFIED_NAME_IS_TEMPLATE (in SCOPE_REF)
       DECLTYPE_FOR_INIT_CAPTURE (in DECLTYPE_TYPE)
+      CONSTRUCTOR_IS_DEPENDENT (in CONSTRUCTOR)
       TINFO_USED_TEMPLATE_ID (in TEMPLATE_INFO)
       PACK_EXPANSION_SIZEOF_P (in *_PACK_EXPANSION)
       OVL_USING_P (in OVERLOAD)
@@ -4205,6 +4206,11 @@ more_aggr_init_expr_args_p (const aggr_init_expr_arg_iterator *iter)
    B b{1,2}, not B b({1,2}) or B b = {1,2}.  */
 #define CONSTRUCTOR_IS_DIRECT_INIT(NODE) (TREE_LANG_FLAG_0 (CONSTRUCTOR_CHECK (NODE)))
 
+/* True if this CONSTRUCTOR is instantiation-dependent and needs to be
+   substituted.  */
+#define CONSTRUCTOR_IS_DEPENDENT(NODE) \
+  (TREE_LANG_FLAG_1 (CONSTRUCTOR_CHECK (NODE)))
+
 /* True if this CONSTRUCTOR should not be used as a variable initializer
    because it was loaded from a constexpr variable with mutable fields.  */
 #define CONSTRUCTOR_MUTABLE_POISON(NODE) \
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 48c180c..f8b3054 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -25815,6 +25815,11 @@ instantiation_dependent_r (tree *tp, int *walk_subtrees,
 	return *tp;
       break;
 
+    case CONSTRUCTOR:
+      if (CONSTRUCTOR_IS_DEPENDENT (*tp))
+	return *tp;
+      break;
+
     default:
       break;
     }
diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c
index 7219139..786f18a 100644
--- a/gcc/cp/semantics.c
+++ b/gcc/cp/semantics.c
@@ -2795,11 +2795,14 @@ finish_compound_literal (tree type, tree compound_literal,
 	  return error_mark_node;
       }
 
-  if (processing_template_decl)
+  if (instantiation_dependent_expression_p (compound_literal)
+      || dependent_type_p (type))
     {
       TREE_TYPE (compound_literal) = type;
       /* Mark the expression as a compound literal.  */
       TREE_HAS_CONSTRUCTOR (compound_literal) = 1;
+      /* And as instantiation-dependent.  */
+      CONSTRUCTOR_IS_DEPENDENT (compound_literal) = true;
       if (fcl_context == fcl_c99)
 	CONSTRUCTOR_C99_COMPOUND_LITERAL (compound_literal) = 1;
       return compound_literal;
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 5438d4f..9149664 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,12 @@
 2019-01-27  Marek Polacek  <polacek@redhat.com>
 
+	PR c++/88815 - narrowing conversion lost in decltype.
+	PR c++/78244 - narrowing conversion in template not detected.
+	* g++.dg/cpp0x/Wnarrowing15.C: New test.
+	* g++.dg/cpp0x/Wnarrowing16.C: New test.
+	* g++.dg/cpp0x/constexpr-decltype3.C: New test.
+	* g++.dg/cpp1y/Wnarrowing1.C: New test.
+
 	PR c++/89024 - ICE with incomplete enum type.
 	* g++.dg/cpp0x/enum37.C: New test.
 
diff --git a/gcc/testsuite/g++.dg/cpp0x/Wnarrowing15.C b/gcc/testsuite/g++.dg/cpp0x/Wnarrowing15.C
new file mode 100644
index 0000000..4e7c17d
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/Wnarrowing15.C
@@ -0,0 +1,14 @@
+// PR c++/78244
+// { dg-do compile { target c++11 } }
+
+template <typename T>
+auto f1() -> decltype(int{2.0}, void()) { } // { dg-error "narrowing conversion" }
+
+template <typename T>
+auto f2() -> decltype(int{2.0}) { return 1; } // { dg-error "narrowing conversion" }
+
+template <typename T>
+auto f3() -> decltype(void(), int{2.0}) { return 1; } // { dg-error "narrowing conversion" }
+
+template <typename T>
+auto f4() -> decltype((int{2.0})) { return 1; } // { dg-error "narrowing conversion" }
diff --git a/gcc/testsuite/g++.dg/cpp0x/Wnarrowing16.C b/gcc/testsuite/g++.dg/cpp0x/Wnarrowing16.C
new file mode 100644
index 0000000..21394be
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/Wnarrowing16.C
@@ -0,0 +1,16 @@
+// PR c++/78244
+// { dg-do compile { target c++11 } }
+
+struct S { int d; };
+
+template <typename T>
+auto f1() -> decltype(S{2.0}, void()) { } // { dg-error "narrowing conversion" }
+
+template <typename T>
+auto f2() -> decltype(S{2.0}, 1) { return 1; } // { dg-error "narrowing conversion" }
+
+template <typename T>
+auto f3() -> decltype(void(), S{2.0}, 1) { return 1; } // { dg-error "narrowing conversion" }
+
+template <typename T>
+auto f4() -> decltype((S{2.0}, 1)) { return 1; } // { dg-error "narrowing conversion" }
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-decltype3.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-decltype3.C
new file mode 100644
index 0000000..fd05366
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-decltype3.C
@@ -0,0 +1,25 @@
+// PR c++/88815
+// { dg-do compile { target c++11 } }
+
+struct true_type {
+    constexpr operator bool() const { return true; }
+};
+
+struct false_type {
+    constexpr operator bool() const { return false; }
+};
+
+template<int (*p)()>
+true_type is_constexpr_impl(decltype(int{(p(), 0U)}));
+
+template<int (*p)()>
+false_type is_constexpr_impl(...);
+
+template<int (*p)()>
+using is_constexpr = decltype(is_constexpr_impl<p>(0));
+
+constexpr int f() { return 0; }
+int g() { return 0; }
+
+static_assert(is_constexpr<f>(), "");
+static_assert(!is_constexpr<g>(), "");
diff --git a/gcc/testsuite/g++.dg/cpp1y/Wnarrowing1.C b/gcc/testsuite/g++.dg/cpp1y/Wnarrowing1.C
new file mode 100644
index 0000000..e1e4995
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/Wnarrowing1.C
@@ -0,0 +1,5 @@
+// PR c++/78244
+// { dg-do compile { target c++14 } }
+
+template<typename>
+decltype(int{1.1}) v; // { dg-error "narrowing conversion" }