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Re: [PATCH] PR 53528 c++/ C++11 Generalized Attribute support

On 07/26/2012 11:19 AM, Dodji Seketeli wrote:
+// Example taken from dcl.attr.grammar:
+int p[10];
+void f()
+    int x = 42, y[5];
+    /* Here, the '[[gnu::' should have introduced an attribute, ont a
+       lambda invocation an array subscripting expression.  */
+    int(p[[gnu::x] { return x; }()]); // { dg-error "expected|consecutive" }
+    /* Likewise, the '[[gnu::' is invalid here.  */
+    y[[gnu::] { return 2; }()] = 2; // { dg-error "expected|consecutive" }

The example in the standard doesn't have gnu:: in it. Search and replace error?

+      if (cp_parser_require (parser, CPP_CLOSE_SQUARE, RT_CLOSE_SQUARE) == NULL
+         || cp_parser_require (parser, CPP_CLOSE_SQUARE, RT_CLOSE_SQUARE) == NULL)

Let's use ! rather than == NULL so that these lines fit in 80 chars.

+      /* If E is a constant, fold it and return it right away.
+        Otherwise, build an ALIGNOF_EXPR that will be substituted
+        into, later at template instantiation time.  */
+      tree cst = TYPE_P (e) ? NULL_TREE : cxx_constant_value (e);

I think you want fold_non_dependent_expr_sfinae rather than cxx_constant_value.

+      /*
+        [dcl.align]/3

Extra newline.

+int **** [[gnu::format(printf, 1, 2)]] foo(const char *, ...);

This seems wrong; you can't apply the format attribute to a pointer type.

About your earlier question on IRC, the solution to the problem you're having with

struct A {int i;} [[gnu::aligned(16)]] a;

is that C++11 attributes after the closing brace should not be passed to finish_struct. Instead, we should apply them to the type (without TYPE_IN_PLACE) after the type is complete.

+typedef union { int i; } U [[gnu::transparent_union]];

For the same reason, this should also be rejected; the testcase should put the attribute before the opening brace. We accept this with GNU-style attributes for backward compatibility, but there's no reason to propagate that lossage into the new syntax.

+template<typename T> struct A
+  void foo() const;
+} [[gnu::aligned(4)]];


+ typedef void ([[gnu::__stdcall__]] T::*F) (L*);

I don't think a C++11 attribute can appear in this position. I think it should be

typedef void (T::*F)(L*) [[gnu::__stdcall__]]

+ virtual void [[gnu::__stdcall__]] A(L *listener) = 0;

Similarly, here the stdcall attribute appertains to "void", which makes no sense.

+S [[gnu::__stdcall__]] getS();
+extern int * ([[gnu::stdcall]] *fooPtr)( void);
+int * [[gnu::stdcall]] myFn01( void) { return 0; }


+ typedef [[gnu::aligned (16)]] struct {

This also seems ill-formed, as there are no type-specifiers before the attribute, so there's nothing for it to appertain to.

+one(void); // OK

noreturn doesn't make sense for "int". Nor does unused, really. C++11 attributes that appertain to the function must either come before any specifiers or after the declarator.

+struct A<int>;                 // { dg-warning "attribute" }

Here the patch is giving the wrong warning; it complains about applying the attribute to A<int>, but actually we should be warning about an attribute that would appertain to all the declarators in a declaration with no declarators for it to appertain to.

+[[gnu::deprecated]] enum E { E0 };     // { dg-warning "attribute ignored in declaration of" }
+// { dg-message "must follow the" "" { target *-*-* } 3 }

Same here.

+         if (strcmp (attr_name, IDENTIFIER_POINTER (get_attribute_name (list))) == 0)
+      gcc_checking_assert (TREE_CODE (get_attribute_name (list)) == IDENTIFIER_NODE);
+             for (a = lookup_ident_attribute (get_attribute_name (a2), attributes);
+                  a = lookup_ident_attribute (get_attribute_name (a2), TREE_CHAIN (a)))

Line too long.

+  /* A given attribute has been parsed as a C++-11 generalized
+     attribute.  */

Let's drop the word "generalized" throughout the patch. I don't see how these attributes are any more generalized than GNU attributes; we should just describe them as C++11 attributes.

+cxx_11_attribute_p (const_tree attr)

Let's change cxx_11 to cxx11.


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