re PR c/4787 (Different anonymous variables declared but only one allocated when the initialization is the same)

	* c-common.def (COMPOUND_LITERAL_EXPR): New.
	* c-common.c (c_expand_expr): Handle COMPOUND_LITERAL_EXPR.
	(c_staticp): New function.
	* c-common.h (COMPOUND_LITERAL_EXPR_DECL): New.
	(c_staticp): Declare.
	* c-typeck.c (default_function_array_conversion, build_unary_op):
	Don't handle CONSTRUCTOR specially.
	(lvalue_p, mark_addressable): Handle COMPOUND_LITERAL_EXPR.
	* c-decl.c (build_compound_literal): New function.
	* c-tree.h (build_compound_literal): Declare.
	* c-parse.in (primary): Use build_compound_literal.
	* c-lang.c (LANG_HOOKS_STATICP): Define.
	* objc/objc-lang.c (LANG_HOOKS_STATICP): Likewise.
	* doc/c-tree.texi: Document COMPOUND_LITERAL_EXPR.
	* doc/extend.texi: Update documentation of compound literals.
	Fixes PR c/4787.

testsuite:
	* gcc.c-torture/execute/20000722-1.x,
	gcc.c-torture/execute/20010123-1.x: Remove.
	* gcc.c-torture/compile/init-3.c: Don't use a compound literal.
	* gcc.dg/c90-complit-1.c, gcc.dg/c99-complit-1.c,
	gcc.dg/c99-complit-2.c: New tests.

From-SVN: r47629

2 files changed, 15 insertions, 20 deletions

diff --git a/gcc/doc/c-tree.texi b/gcc/doc/c-tree.texi
index dd21ae6..3db3d7f 100644
--- a/gcc/doc/c-tree.texi
+++ b/gcc/doc/c-tree.texi
@@ -1738,6 +1738,7 @@ This macro returns the attributes on the type @var{type}.
 @tindex COND_EXPR
 @tindex CALL_EXPR
 @tindex CONSTRUCTOR
+@tindex COMPOUND_LITERAL_EXPR
 @tindex STMT_EXPR
 @tindex BIND_EXPR
 @tindex LOOP_EXPR
@@ -2201,6 +2202,15 @@ next available array element.
 Conceptually, before any initialization is done, the entire area of
 storage is initialized to zero.
 
+@item COMPOUND_LITERAL_EXPR
+@findex COMPOUND_LITERAL_EXPR_DECL
+These nodes represent ISO C99 compound literals.  The
+@code{COMPOUND_LITERAL_EXPR_DECL} is an anonymous @code{VAR_DECL} for
+the unnamed object represented by the compound literal; the
+@code{DECL_INITIAL} of that @code{VAR_DECL} is a @code{CONSTRUCTOR}
+representing the brace-enclosed list of initializers in the compound
+literal.
+
 @item SAVE_EXPR
 
 A @code{SAVE_EXPR} represents an expression (possibly involving
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index 781fa99..cf275f1 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -1608,9 +1608,8 @@ foo (float f, float g)
 ISO C99 supports compound literals.  A compound literal looks like
 a cast containing an initializer.  Its value is an object of the
 type specified in the cast, containing the elements specified in
-the initializer.  (GCC does not yet implement the full ISO C99 semantics
-for compound literals.)  As an extension, GCC supports compound literals
-in C89 mode and in C++.
+the initializer; it is an lvalue.  As an extension, GCC supports
+compound literals in C89 mode and in C++.
 
 Usually, the specified type is a structure.  Assume that
 @code{struct foo} and @code{structure} are declared as shown:
@@ -1638,28 +1637,14 @@ This is equivalent to writing the following:
 
 You can also construct an array.  If all the elements of the compound literal
 are (made up of) simple constant expressions, suitable for use in
-initializers, then the compound literal is an lvalue and can be coerced to a
-pointer to its first element, as shown here:
+initializers of objects of static storage duration, then the compound
+literal can be coerced to a pointer to its first element and used in
+such an initializer, as shown here:
 
 @example
 char **foo = (char *[]) @{ "x", "y", "z" @};
 @end example
 
-Array compound literals whose elements are not simple constants are
-not very useful, because the compound literal is not an lvalue; ISO C99
-specifies that it is, being a temporary object with automatic storage
-duration associated with the enclosing block, but GCC does not yet
-implement this.  There are currently only two valid ways to use it with
-GCC: to subscript it, or initialize
-an array variable with it.  The former is probably slower than a
-@code{switch} statement, while the latter does the same thing an
-ordinary C initializer would do.  Here is an example of
-subscripting an array compound literal:
-
-@example
-output = ((int[]) @{ 2, x, 28 @}) [input];
-@end example
-
 Compound literals for scalar types and union types are is
 also allowed, but then the compound literal is equivalent
 to a cast.