[PATCH] GSoC Micoproject: Hunt down signed int flags

[Saurav Sachidanand <sauravsachidanand@gmail.com>]

This is patch is for a suggested micro project for GSoC 2016; namely,
that of searching for a field of a struct that is of signed integral
type and used as a collection of multiple bits, and converting it to
an unsigned type if the MSB isn’t used in any special way.

Two structs, `pattern` defined in attr.c and `exclude` defined in dir.h,
have a `flags` field of signed int type. The fields of both structs take
on values from the same set of positive integers {1, 4, 8, 16},
enumerated through the marco EXC_FLAG_*. `pattern` is used only in attr.c,
and `exclude` is used only in builtin/check-ignore.c and dir.c, and in
those files, either, the value of `flags` is checked using the `&` operator
(e.g.: flags & EXC_FLAG_NODIR), or the value of `flags` is first set to 0
and then set to any one of {1, 4, 8, 16} using the `|=` operator
(e.g.: flags |= EXC_FLAG_NODIR). And, so it does not appear that the MSB
of `flags` is used in any special way. Therefore, I thought to change the
type of `flags` in the definitions of both structs to `unsigned int`.

Furthermore, `flags` is passed by reference (of `pattern` in attr.c and of
`exclude` in dir.c) to the function `parse_exclude_pattern` defined in
dir.c, that accepts an `int *` type for `flags`. When make was run, it gave
a warning for ‘converting between pointers to integer types of different
sign’, so I changed the type of that respective argument to `unsigned int *`.

In the end, running make to build didn’t produce any more warnings, and
running make in t/ didn’t produce any breakage that wasn’t ‘#TODO known
breakage’.

I also thought it’d be helpful to add the comment /* EXC_FLAG_* */ next
to `flags` of `exclude`, just like it exists for `flags` of `pattern`.

Signed-off-by: Saurav Sachidanand <sauravsachidanand@gmail.com>
---
 attr.c | 2 +-
 dir.c  | 4 ++--
 dir.h  | 4 ++--
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/attr.c b/attr.c
index 086c08d..874f726 100644
--- a/attr.c
+++ b/attr.c
@@ -124,7 +124,7 @@ struct pattern {
 	const char *pattern;
 	int patternlen;
 	int nowildcardlen;
-	int flags;		/* EXC_FLAG_* */
+	unsigned int flags;		/* EXC_FLAG_* */
 };
 
 /*
diff --git a/dir.c b/dir.c
index f0b6d0a..2d657e1 100644
--- a/dir.c
+++ b/dir.c
@@ -457,7 +457,7 @@ int no_wildcard(const char *string)
 
 void parse_exclude_pattern(const char **pattern,
 			   int *patternlen,
-			   int *flags,
+			   unsigned int *flags,
 			   int *nowildcardlen)
 {
 	const char *p = *pattern;
@@ -498,7 +498,7 @@ void add_exclude(const char *string, const char *base,
 {
 	struct exclude *x;
 	int patternlen;
-	int flags;
+	unsigned int flags;
 	int nowildcardlen;
 
 	parse_exclude_pattern(&string, &patternlen, &flags, &nowildcardlen);
diff --git a/dir.h b/dir.h
index cd46f30..6d205f0 100644
--- a/dir.h
+++ b/dir.h
@@ -27,7 +27,7 @@ struct exclude {
 	int nowildcardlen;
 	const char *base;
 	int baselen;
-	int flags;
+	unsigned int flags;		/* EXC_FLAG_* */
 
 	/*
 	 * Counting starts from 1 for line numbers in ignore files,
@@ -241,7 +241,7 @@ extern struct exclude_list *add_exclude_list(struct dir_struct *dir,
 extern int add_excludes_from_file_to_list(const char *fname, const char *base, int baselen,
 					  struct exclude_list *el, int check_index);
 extern void add_excludes_from_file(struct dir_struct *, const char *fname);
-extern void parse_exclude_pattern(const char **string, int *patternlen, int *flags, int *nowildcardlen);
+extern void parse_exclude_pattern(const char **string, int *patternlen, unsigned int *flags, int *nowildcardlen);
 extern void add_exclude(const char *string, const char *base,
 			int baselen, struct exclude_list *el, int srcpos);
 extern void clear_exclude_list(struct exclude_list *el);
-- 
2.7.1.339.g0233b80