fixes for type-punning warnings in GCC 4.1

[Alexandre Oliva <aoliva@redhat.com>]

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Hi,

This patch fixes the type-punning warnings that the GCC 4.1 branch
issues when compiling the GDB code base.

The fixes for the .y files are safe, since the casts only perform a
non-identity conversion when code paths that are never taken.  The two
other cases are situations in which the use of opaque types forces us
to violate the ISO C string aliasing rules; the one in tui/tui-data.c
is safe in that we never access the affected data structures with the
wrong type.  In varobj.c that's much trickier to prove, but since it's
in a separate translation unit from the call, what we have now is no
safer than what we get after my patch.

Build-tested on amd64-linux-gnu.  Ok to install?


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Index: gdb/ChangeLog
2005-12-19  Alexandre Oliva  <aoliva@redhat.com>

	* c-exp.y (parse_number): Silence type-punning warnings.
	* jv-exp.y (parse_number): Likewise.
	* objc-exp.y (parse_number): Likewise.
	* p-exp.y (parse_number): Likewise.
	* tui/tui-data.c (source_windows): Likewise.
	* varobj.c (free_variable): Likewise.

Index: gdb/c-exp.y
===================================================================
--- gdb/c-exp.y.orig	2005-12-19 15:07:39.000000000 -0200
+++ gdb/c-exp.y	2005-12-19 15:25:35.000000000 -0200
@@ -1082,9 +1082,9 @@
       p[len] = 0;	/* null-terminate the token */
 
       if (sizeof (putithere->typed_val_float.dval) <= sizeof (float))
-	num = sscanf (p, "%g%s", (float *) &putithere->typed_val_float.dval,s);
+	num = sscanf (p, "%g%s", (float *) (void *) &putithere->typed_val_float.dval,s);
       else if (sizeof (putithere->typed_val_float.dval) <= sizeof (double))
-	num = sscanf (p, "%lg%s", (double *) &putithere->typed_val_float.dval,s);
+	num = sscanf (p, "%lg%s", (double *) (void *) &putithere->typed_val_float.dval,s);
       else
 	{
 #ifdef SCANF_HAS_LONG_DOUBLE
Index: gdb/jv-exp.y
===================================================================
--- gdb/jv-exp.y.orig	2005-12-19 15:07:41.000000000 -0200
+++ gdb/jv-exp.y	2005-12-19 15:24:53.000000000 -0200
@@ -714,9 +714,9 @@
 
       p[len] = 0;	/* null-terminate the token */
       if (sizeof (putithere->typed_val_float.dval) <= sizeof (float))
-	num = sscanf (p, "%g%c", (float *) &putithere->typed_val_float.dval, &c);
+	num = sscanf (p, "%g%c", (float *) (void *) &putithere->typed_val_float.dval, &c);
       else if (sizeof (putithere->typed_val_float.dval) <= sizeof (double))
-	num = sscanf (p, "%lg%c", (double *) &putithere->typed_val_float.dval, &c);
+	num = sscanf (p, "%lg%c", (double *) (void *) &putithere->typed_val_float.dval, &c);
       else
 	{
 #ifdef SCANF_HAS_LONG_DOUBLE
Index: gdb/objc-exp.y
===================================================================
--- gdb/objc-exp.y.orig	2005-12-19 15:07:45.000000000 -0200
+++ gdb/objc-exp.y	2005-12-19 15:24:53.000000000 -0200
@@ -1026,9 +1026,9 @@
       /* It's a float since it contains a point or an exponent.  */
 
       if (sizeof (putithere->typed_val_float.dval) <= sizeof (float))
-	sscanf (p, "%g", (float *)&putithere->typed_val_float.dval);
+	sscanf (p, "%g", (float *) (void *) &putithere->typed_val_float.dval);
       else if (sizeof (putithere->typed_val_float.dval) <= sizeof (double))
-	sscanf (p, "%lg", (double *)&putithere->typed_val_float.dval);
+	sscanf (p, "%lg", (double *) (void *) &putithere->typed_val_float.dval);
       else
 	{
 #ifdef PRINTF_HAS_LONG_DOUBLE
Index: gdb/p-exp.y
===================================================================
--- gdb/p-exp.y.orig	2005-12-19 15:07:45.000000000 -0200
+++ gdb/p-exp.y	2005-12-19 15:24:53.000000000 -0200
@@ -800,9 +800,9 @@
 
       p[len] = 0;	/* null-terminate the token */
       if (sizeof (putithere->typed_val_float.dval) <= sizeof (float))
-	num = sscanf (p, "%g%c", (float *) &putithere->typed_val_float.dval,&c);
+	num = sscanf (p, "%g%c", (float *) (void *) &putithere->typed_val_float.dval,&c);
       else if (sizeof (putithere->typed_val_float.dval) <= sizeof (double))
-	num = sscanf (p, "%lg%c", (double *) &putithere->typed_val_float.dval,&c);
+	num = sscanf (p, "%lg%c", (double *) (void *) &putithere->typed_val_float.dval,&c);
       else
 	{
 #ifdef SCANF_HAS_LONG_DOUBLE
Index: gdb/tui/tui-data.c
===================================================================
--- gdb/tui/tui-data.c.orig	2005-12-19 15:07:52.000000000 -0200
+++ gdb/tui/tui-data.c	2005-12-19 15:24:53.000000000 -0200
@@ -44,7 +44,13 @@
 static struct tui_gen_win_info _locator;
 static struct tui_gen_win_info exec_info[2];
 static struct tui_win_info * src_win_list[2];
-static struct tui_list source_windows = {(void **) src_win_list, 0};
+/* The intermediate cast to void* silences a type-punning warning
+   issued by GCC.  The use appears to be safe, since we always access
+   source_windows.list with type void**, and whenever we access one of
+   the list members, we cast it to struct tui_win_info*.  The
+   interface of struct tui_list should probably be redesigned with
+   less type opacity to avoid type punning.  -aoliva */
+static struct tui_list source_windows = {(void **) (void *) src_win_list, 0};
 static int default_tab_len = DEFAULT_TAB_LEN;
 static struct tui_win_info * win_with_focus = (struct tui_win_info *) NULL;
 static struct tui_layout_def layout_def =
Index: gdb/varobj.c
===================================================================
--- gdb/varobj.c.orig	2005-12-19 15:07:50.000000000 -0200
+++ gdb/varobj.c	2005-12-19 15:24:53.000000000 -0200
@@ -1374,7 +1374,7 @@
   /* Free the expression if this is a root variable. */
   if (var->root->rootvar == var)
     {
-      free_current_contents ((char **) &var->root->exp);
+      free_current_contents (&var->root->exp);
       xfree (var->root);
     }
 

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-- 
Alexandre Oliva         http://www.lsd.ic.unicamp.br/~oliva/
Red Hat Compiler Engineer   aoliva@{redhat.com, gcc.gnu.org}
Free Software Evangelist  oliva@{lsd.ic.unicamp.br, gnu.org}