* c-typeck.c (digest_init): Allow initializing

	static storage duration objects with compound literals.
	* doc/extend.texi (Compound literals): Document the extension.

	* gcc.dg/gnu89-init-1.c: New test.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@47945 138bc75d-0d04-0410-961f-82ee72b054a4

5 files changed, 84 insertions, 2 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index ed8c11b95fe..acd75f9769e 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2001-12-12  Jakub Jelinek  <jakub@redhat.com>
+
+	* c-typeck.c (digest_init): Allow initializing
+	static storage duration objects with compound literals.
+	* doc/extend.texi (Compound literals): Document the extension.
+
 2001-12-12  Richard Henderson  <rth@redhat.com>
 
 	* emit-rtl.c (adjust_address_1): Always copy address to avoid
diff --git a/gcc/c-typeck.c b/gcc/c-typeck.c
index 56775049a1c..f3f7d096964 100644
--- a/gcc/c-typeck.c
+++ b/gcc/c-typeck.c
@@ -4780,8 +4780,19 @@ digest_init (type, init, require_constant, constructor_constant)
     {
       if (code == POINTER_TYPE)
 	inside_init = default_function_array_conversion (inside_init);
-      else if (code == ARRAY_TYPE && TREE_CODE (inside_init) != STRING_CST
-	       && TREE_CODE (inside_init) != CONSTRUCTOR)
+
+      if (require_constant && !flag_isoc99
+	  && TREE_CODE (inside_init) == COMPOUND_LITERAL_EXPR)
+	{
+	  /* As an extension, allow initializing objects with static storage
+	     duration with compound literals (which are then treated just as
+	     the brace enclosed list they contain).  */
+	  tree decl = COMPOUND_LITERAL_EXPR_DECL (inside_init);
+	  inside_init = DECL_INITIAL (decl);
+	}
+
+      if (code == ARRAY_TYPE && TREE_CODE (inside_init) != STRING_CST
+	  && TREE_CODE (inside_init) != CONSTRUCTOR)
 	{
 	  error_init ("array initialized from non-constant array expression");
 	  return error_mark_node;
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index 80addd33160..9b97805f151 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -1649,6 +1649,30 @@ Compound literals for scalar types and union types are is
 also allowed, but then the compound literal is equivalent
 to a cast.
 
+As a GNU extension, GCC allows initialization of objects with static storage
+duration by compound literals (which is not possible in ISO C99, because
+the initializer is not a constant).
+It is handled as if the object was initialized only with the bracket
+enclosed list if compound literal's and object types match.
+The initializer list of the compound literal must be constant.
+If the object being initialized has array type of unknown size, the size is
+determined by compound literal's initializer list, not by the size of the
+compound literal.
+
+@example
+static struct foo x = (struct foo) @{1, 'a', 'b'@};
+static int y[] = (int []) @{1, 2, 3@};
+static int z[] = (int [3]) @{1@};
+@end example
+
+@noindent
+The above lines are equivalent to the following:
+@example
+static struct foo x = @{1, 'a', 'b'@};
+static int y[] = @{1, 2, 3@};
+static int z[] = @{1@};
+@end example
+
 @node Designated Inits
 @section Designated Initializers
 @cindex initializers with labeled elements
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 534af00eea3..489171423d4 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2001-12-12  Jakub Jelinek  <jakub@redhat.com>
+
+	* gcc.dg/gnu89-init-1.c: New test.
+
 2001-12-12  Nathan Sidwell  <nathan@codesourcery.com>
 
 	* g++.old-deja/g++.brendan/crash56.C: Adjust implicit typename.
diff --git a/gcc/testsuite/gcc.dg/gnu89-init-1.c b/gcc/testsuite/gcc.dg/gnu89-init-1.c
new file mode 100644
index 00000000000..dae61b57da5
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/gnu89-init-1.c
@@ -0,0 +1,37 @@
+/* Test for GNU extensions to compound literals */
+/* Origin: Jakub Jelinek <jakub@redhat.com> */
+/* { dg-do run } */
+/* { dg-options "-std=gnu89" } */
+
+extern void abort (void);
+extern void exit (int);
+
+struct A { int i; int j; int k[4]; };
+struct B { };
+
+/* As a GNU extension, we allow initialization of objects with static storage
+   duration by compound literals.  It is handled as if the object
+   was initialized only with the bracket enclosed list if compound literal's
+   and object types match.  If the object being initialized has array type
+   of unknown size, the size is determined by compound literal's initializer
+   list, not by size of the compound literal.  */
+
+struct A a = (struct A) { .j = 6, .k[2] = 12 };
+struct B b = (struct B) { };
+int c[] = (int []) { [2] = 6, 7, 8 };
+int d[] = (int [3]) { 1 };
+
+int main (void)
+{
+  if (a.i || a.j != 6 || a.k[0] || a.k[1] || a.k[2] != 12 || a.k[3])
+    abort ();
+  if (c[0] || c[1] || c[2] != 6 || c[3] != 7 || c[4] != 8)
+    abort ();
+  if (sizeof (c) != 5 * sizeof (int))
+    abort ();
+  if (d[0] != 1)
+    abort ();
+  if (sizeof (d) != sizeof (int))
+    abort ();
+  exit (0);
+}