re PR middle-end/23497 (Bogus 'is used uninitialized...' warning about std::complex<T>)

        PR middle-end/23497
        * tree-ssa.c (warn_uninitialized_var): Skip real and imaginary
        parts of an SSA_NAME.

From-SVN: r107107

gcc/ChangeLog

+2005-11-16  Richard Henderson  <rth@redhat.com>
+
+	PR middle-end/23497
+	* tree-ssa.c (warn_uninitialized_var): Skip real and imaginary
+	parts of an SSA_NAME.
+
 2005-11-16  Richard Earnshaw  <richard.earnshaw@arm.com>
 
 	PR target/24861

gcc/testsuite/gcc.dg/uninit-12.c

+/* PR 23497 */
+/* { dg-do compile } */
+/* { dg-options "-O -Wuninitialized" } */
+
+typedef _Complex float C;
+C foo()
+{
+  C f;
+  __real__ f = 0;
+  __imag__ f = 0;
+  return f;
+}

gcc/testsuite/gcc.dg/uninit-13.c

+/* { dg-do compile } */
+/* { dg-options "-O -Wuninitialized" } */
+
+typedef _Complex float C;
+C foo()
+{
+  C f;
+  __imag__ f = 0;
+  return f;		/* { dg-warning "" "uninit" { xfail *-*-* } } */
+}

gcc/tree-ssa.c

@@ -1155,14 +1155,29 @@ warn_uninitialized_var (tree *tp, int *walk_subtrees, void *data)
 {
   tree t = *tp;
 
-  /* We only do data flow with SSA_NAMEs, so that's all we can warn about.  */
-  if (TREE_CODE (t) == SSA_NAME)
+  switch (TREE_CODE (t))
     {
+    case SSA_NAME:
+      /* We only do data flow with SSA_NAMEs, so that's all we
+	 can warn about.  */
       warn_uninit (t, "%H%qD is used uninitialized in this function", data);
       *walk_subtrees = 0;
+      break;
+
+    case REALPART_EXPR:
+    case IMAGPART_EXPR:
+      /* The total store transformation performed during gimplification
+	 creates uninitialized variable uses.  If all is well, these will
+	 be optimized away, so don't warn now.  */
+      if (TREE_CODE (TREE_OPERAND (t, 0)) == SSA_NAME)
+	*walk_subtrees = 0;
+      break;
+
+    default:
+      if (IS_TYPE_OR_DECL_P (t))
+	*walk_subtrees = 0;
+      break;
     }
-  else if (IS_TYPE_OR_DECL_P (t))
-    *walk_subtrees = 0;
 
   return NULL_TREE;
 }