GCC 8 backports

[Marek Polacek <polacek@redhat.com>]

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I'm backporting these 5 patches to gcc-8.

Marek

[-- Attachment #2: gcc8-pr88857.patch --]
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2019-02-27  Marek Polacek  <polacek@redhat.com>

	PR c++/88857 - ICE with value-initialization of argument in template.
	* call.c (convert_like_real): Don't call build_value_init in template.

--- gcc/cp/call.c
+++ gcc/cp/call.c
@@ -7005,7 +7005,8 @@ convert_like_real (conversion *convs, tree expr, tree fn, int argnum,
 	/* If we're initializing from {}, it's value-initialization.  */
 	if (BRACE_ENCLOSED_INITIALIZER_P (expr)
 	    && CONSTRUCTOR_NELTS (expr) == 0
-	    && TYPE_HAS_DEFAULT_CONSTRUCTOR (totype))
+	    && TYPE_HAS_DEFAULT_CONSTRUCTOR (totype)
+	    && !processing_template_decl)
 	  {
 	    bool direct = CONSTRUCTOR_IS_DIRECT_INIT (expr);
 	    if (abstract_virtuals_error_sfinae (NULL_TREE, totype, complain))
--- /dev/null
+++ gcc/testsuite/g++.dg/cpp0x/initlist-value4.C
@@ -0,0 +1,12 @@
+// PR c++/88857
+// { dg-do compile { target c++11 } }
+
+class S { int a; };
+void foo (const S &, int);
+
+template <int N>
+void
+bar ()
+{
+  foo ({}); // { dg-error "too few arguments to function" }
+}

[-- Attachment #3: gcc8-pr89214.patch --]
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2019-03-25  Marek Polacek  <polacek@redhat.com>
 
	PR c++/89214 - ICE when initializing aggregates with bases.
	* typeck2.c (digest_init_r): Warn about object slicing instead of
	crashing.

--- gcc/cp/typeck2.c
+++ gcc/cp/typeck2.c
@@ -1209,8 +1209,29 @@ digest_init_r (tree type, tree init, int nested, int flags,
     {
       tree elt = CONSTRUCTOR_ELT (stripped_init, 0)->value;
       if (reference_related_p (type, TREE_TYPE (elt)))
-	/* We should have fixed this in reshape_init.  */
-	gcc_unreachable ();
+	{
+	  /* In C++17, aggregates can have bases, thus participate in
+	     aggregate initialization.  In the following case:
+
+	       struct B { int c; };
+	       struct D : B { };
+	       D d{{D{{42}}}};
+
+	    there's an extra set of braces, so the D temporary initializes
+	    the first element of d, which is the B base subobject.  The base
+	    of type B is copy-initialized from the D temporary, causing
+	    object slicing.  */
+	  tree field = next_initializable_field (TYPE_FIELDS (type));
+	  if (field && DECL_FIELD_IS_BASE (field))
+	    {
+	      if (warning_at (loc, 0, "initializing a base class of type %qT "
+			      "results in object slicing", TREE_TYPE (field)))
+		inform (loc, "remove %<{ }%> around initializer");
+	    }
+	  else
+	    /* We should have fixed this in reshape_init.  */
+	    gcc_unreachable ();
+	}
     }
 
   if (BRACE_ENCLOSED_INITIALIZER_P (stripped_init)
--- /dev/null
+++ gcc/testsuite/g++.dg/cpp1z/aggr-base8.C
@@ -0,0 +1,48 @@
+// PR c++/89214
+// { dg-do compile { target c++17 } }
+
+struct A
+{
+  A (int);
+};
+
+struct BB
+{
+  A a;
+};
+
+struct B : BB
+{
+};
+
+void
+foo ()
+{
+  B b1 = {42};
+  B b2 = {{42}};
+  B b3 = {{{42}}};
+
+  B b4 = B{42};
+  B b5 = B{{42}};
+  B b6 = B{{{42}}};
+
+  B b7 = {B{42}};
+  B b8 = {B{{42}}};
+  B b9 = {B{{{42}}}};
+
+  B b10 = {{B{42}}}; // { dg-warning "initializing a base class of type .BB. results in object slicing" }
+  B b11 = {{B{{42}}}}; // { dg-warning "initializing a base class of type .BB. results in object slicing" }
+  B b12 = {{B{{{42}}}}}; // { dg-warning "initializing a base class of type .BB. results in object slicing" }
+
+  B bb1{42};
+  B bb2{{42}};
+  B bb3{{{42}}};
+
+  B bb7{B{42}};
+  B bb8{B{{42}}};
+  B bb9{B{{{42}}}};
+
+  B bb10{{B{42}}}; // { dg-warning "initializing a base class of type .BB. results in object slicing" }
+  B bb11{{B{{42}}}}; // { dg-warning "initializing a base class of type .BB. results in object slicing" }
+  B bb12{{B{{{42}}}}}; // { dg-warning "initializing a base class of type .BB. results in object slicing" }
+}
--- /dev/null
+++ gcc/testsuite/g++.dg/cpp1z/aggr-base9.C
@@ -0,0 +1,33 @@
+// PR c++/89214
+// { dg-do compile { target c++17 } }
+
+struct B {
+  int c;
+};
+
+struct D : B { };
+
+void
+foo ()
+{
+  D d1 = {42};
+  D d2 = {{42}};
+  
+  D d4 = D{42};
+  D d5 = D{{42}};
+ 
+  D d7 = {D{42}};
+  D d8 = {D{{42}}};
+
+  D d10 = {{D{42}}}; // { dg-warning "initializing a base class of type .B. results in object slicing" }
+  D d11 = {{D{{42}}}}; // { dg-warning "initializing a base class of type .B. results in object slicing" }
+
+  D dd1{42};
+  D dd2{{42}};
+  
+  D dd7{D{42}};
+  D dd8{D{{42}}};
+
+  D dd10{{D{42}}}; // { dg-warning "initializing a base class of type .B. results in object slicing" }
+  D dd11{{D{{42}}}}; // { dg-warning "initializing a base class of type .B. results in object slicing" }
+}

[-- Attachment #4: gcc8-pr89511.patch --]
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2019-02-27  Marek Polacek  <polacek@redhat.com>

	PR c++/89511 - ICE with using-declaration and unscoped enumerator.
	* parser.c (cp_parser_using_declaration): For an unscoped enum
	only use its context if it's not a function declaration.

--- gcc/cp/parser.c
+++ gcc/cp/parser.c
@@ -19412,7 +19412,8 @@ cp_parser_using_declaration (cp_parser* parser,
 						  /*is_declaration=*/true);
   if (!qscope)
     qscope = global_namespace;
-  else if (UNSCOPED_ENUM_P (qscope))
+  else if (UNSCOPED_ENUM_P (qscope)
+	   && !TYPE_FUNCTION_SCOPE_P (qscope))
     qscope = CP_TYPE_CONTEXT (qscope);
 
   if (access_declaration_p && cp_parser_error_occurred (parser))
--- /dev/null
+++ gcc/testsuite/g++.dg/cpp0x/using-enum-3.C
@@ -0,0 +1,21 @@
+// PR c++/89511
+// { dg-do compile { target c++11 } }
+
+void f ()
+{
+  enum e { a };
+  using e::a; // { dg-error "not a namespace or unscoped enum" }
+}
+
+struct S {
+  enum E { A };
+  using E::A; // { dg-error "type .S. is not a base type for type .S." }
+};
+
+namespace N {
+  enum E { B };
+}
+
+struct T {
+  using N::E::B; // { dg-error "using-declaration for non-member at class scope" }
+};

[-- Attachment #5: gcc8-pr89705.patch --]
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2019-03-25  Marek Polacek  <polacek@redhat.com>

	PR c++/89705 - ICE with reference binding with conversion function.
	* call.c (reference_binding): If the result of the conversion function
	is a prvalue of non-class type, use the cv-unqualified type.

diff --git gcc/cp/call.c gcc/cp/call.c
index f16f2895402..c5ef07d0bee 100644
--- gcc/cp/call.c
+++ gcc/cp/call.c
@@ -1767,6 +1767,9 @@ reference_binding (tree rto, tree rfrom, tree expr, bool c_cast_p, int flags,
 	    && DECL_CONV_FN_P (t->cand->fn))
 	  {
 	    tree ftype = TREE_TYPE (TREE_TYPE (t->cand->fn));
+	    /* A prvalue of non-class type is cv-unqualified.  */
+	    if (TREE_CODE (ftype) != REFERENCE_TYPE && !CLASS_TYPE_P (ftype))
+	      ftype = cv_unqualified (ftype);
 	    int sflags = (flags|LOOKUP_NO_CONVERSION)&~LOOKUP_NO_TEMP_BIND;
 	    conversion *new_second
 	      = reference_binding (rto, ftype, NULL_TREE, c_cast_p,
diff --git gcc/testsuite/g++.dg/cpp0x/rv-conv2.C gcc/testsuite/g++.dg/cpp0x/rv-conv2.C
new file mode 100644
index 00000000000..9b9b154995b
--- /dev/null
+++ gcc/testsuite/g++.dg/cpp0x/rv-conv2.C
@@ -0,0 +1,18 @@
+// PR c++/89705
+// { dg-do compile { target c++11 } }
+
+struct W { operator const volatile int(); };
+const int& rci = W();
+
+struct X { operator const int(); };
+int&& rri = X();
+
+struct Y { operator volatile int(); };
+int&& rri2 = Y();
+
+struct Z { operator const volatile int(); };
+volatile int&& rri3 = Z();
+
+enum E { A };
+struct S { operator const E(); };
+E&& rre = S();

[-- Attachment #6: gcc8-pr89876.patch --]
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2019-03-29  Marek Polacek  <polacek@redhat.com>

	PR c++/89876 - ICE with deprecated conversion.
	* call.c (convert_like_real): Only give warnings with tf_warning.

--- gcc/cp/call.c
+++ gcc/cp/call.c
@@ -7446,7 +7446,8 @@ convert_like_real (conversion *convs, tree expr, tree fn, int argnum,
 
     case ck_qual:
       /* Warn about deprecated conversion if appropriate.  */
-      string_conv_p (totype, expr, 1);
+      if (complain & tf_warning)
+	string_conv_p (totype, expr, 1);
       break;
 
     case ck_ptr:
--- /dev/null
+++ gcc/testsuite/g++.dg/warn/conv5.C
@@ -0,0 +1,11 @@
+// PR c++/89876
+// { dg-do compile { target c++11 } }
+// { dg-prune-output "sorry" }
+
+template <typename T>
+T f (T, char*);
+
+template <typename T>
+decltype (f (T (), "")) g (T) { return ""; } // { dg-error "invalid conversion" }
+
+void h () { g (0); }