gdb/

	Code cleanup.
	* skip.c (skip_function_command, skip_file_command, skip_info): Remove
	unused forward declarations.
	(skip_file_command): Make variables symtab and filename targets const.
	Use proper 0 vs. NULL constant everywhere.
	(skip_function_command): Use proper 0 vs. NULL constant everywhere.
	Include empty line after declarations.  Use GNU spacing in a comment.
	Do not use strlen for end of string check.
	(skip_info): Use proper 0 vs. NULL constant everywhere.  Add column 5
	comments.
	(skip_enable_command, skip_disable_command, skip_delete_command)
	(add_skiplist_entry): Use proper 0 vs. NULL constant everywhere.
	(function_pc_is_marked_for_skip): Make variable filename target const.
	Use proper 0 vs. NULL constant everywhere.  Fix GNU non-compliant
	comment formatting.
	(skip_re_set): Add empty line after function comment.  Use proper 0 vs.
	NULL constant everywhere.  Include empty line after declarations.  Make
	variable symtab target const.  Do not use strlen for end of string
	check.

gdb/doc/
	* gdbint.texinfo (Coding Standards) (C Usage): New rule for 0 vs. NULL.

1 files changed, 19 insertions, 0 deletions

diff --git a/gdb/doc/gdbint.texinfo b/gdb/doc/gdbint.texinfo
index 5dbf7bf..bb7e5e5 100644
--- a/gdb/doc/gdbint.texinfo
+++ b/gdb/doc/gdbint.texinfo
@@ -5907,6 +5907,25 @@ protected with parentheses.)
 Declarations like @samp{struct foo *} should be used in preference to
 declarations like @samp{typedef struct foo @{ @dots{} @} *foo_ptr}.
 
+Zero constant (@code{0}) is not interchangeable with a null pointer
+constant (@code{NULL}) anywhere.  @sc{gcc} does not give a warning for
+such interchange.  Specifically:
+
+@multitable @columnfractions .2 .5
+@item incorrect
+@tab @code{if (pointervar) @{@}}
+@item incorrect
+@tab @code{if (!pointervar) @{@}}
+@item incorrect
+@tab @code{if (pointervar != 0) @{@}}
+@item incorrect
+@tab @code{if (pointervar == 0) @{@}}
+@item correct
+@tab @code{if (pointervar != NULL) @{@}}
+@item correct
+@tab @code{if (pointervar == NULL) @{@}}
+@end multitable
+
 @subsection Function Prototypes
 @cindex function prototypes