Karthik Nayak [off-list ref] writes:

Arnav Bhate [off-list ref] writes:

quoted

There are multiple places, especially in loops, where a signed and an
unsigned data type are compared. Git uses a mix of signed and unsigned
types to store lengths of arrays. This sometimes leads to using a signed
index for an array whose length is stored in an unsigned variable or
vice versa.

Replace signed data types with unsigned data types and vice versa
wherever necessary. In some cases, introduce a new variable, where both
signed and unsigned data types have been used to store lengths of arrays
in the same function, where previously only one variable was used to
iterate over both types. In cases where this is not possible, add
appropriate cast. Remove #define DISABLE_SIGN_COMPARE_WARNINGS.

Signed-off-by: Arnav Bhate <redacted>
---
 pathspec.c | 26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/pathspec.c b/pathspec.c
index 89663645e1..fd7dfdfd84 100644
--- a/pathspec.c
+++ b/pathspec.c

@@ -1,5 +1,4 @@
 #define USE_THE_REPOSITORY_VARIABLE
-#define DISABLE_SIGN_COMPARE_WARNINGS

 #include "git-compat-util.h"
 #include "abspath.h"

@@ -36,6 +35,7 @@ void add_pathspec_matches_against_index(const struct pathspec *pathspec,
 					enum ps_skip_worktree_action sw_action)
 {
 	int num_unmatched = 0, i;
+	unsigned int j;

 	/*
 	 * Since we are walking the index as if we were walking the directory,

@@ -48,8 +48,8 @@ void add_pathspec_matches_against_index(const struct pathspec *pathspec,
 			num_unmatched++;
 	if (!num_unmatched)
 		return;
-	for (i = 0; i < istate->cache_nr; i++) {
-		const struct cache_entry *ce = istate->cache[i];
+	for (j = 0; j < istate->cache_nr; j++) {
+		const struct cache_entry *ce = istate->cache[j];
 		if (sw_action == PS_IGNORE_SKIP_WORKTREE &&
 		    (ce_skip_worktree(ce) || !path_in_sparse_checkout(ce->name, istate)))
 			continue;

While this is correct, now we have 'i' & 'j' as iteration variables,
generally this is used in O(n^2) loops to define the outer and inner
loops. Here, however, we use it to simply define two different types. I
find this deviation from convention a little confusing.

Perhaps, we could simply utilize the option of intializing loop
variables in the loop itself?

  diff --git a/pathspec.c b/pathspec.c
  index 89663645e1..ff8854afb8 100644
  --- a/pathspec.c
  +++ b/pathspec.c
  @@ -35,7 +35,7 @@ void add_pathspec_matches_against_index(const
struct pathspec *pathspec,
   					char *seen,
   					enum ps_skip_worktree_action sw_action)
   {
  -	int num_unmatched = 0, i;
  +	int num_unmatched = 0;

   	/*
   	 * Since we are walking the index as if we were walking the directory,
  @@ -43,12 +43,12 @@ void add_pathspec_matches_against_index(const
struct pathspec *pathspec,
   	 * mistakenly think that the user gave a pathspec that did not match
   	 * anything.
   	 */
  -	for (i = 0; i < pathspec->nr; i++)
  +	for (int i = 0; i < pathspec->nr; i++)
   		if (!seen[i])
   			num_unmatched++;
   	if (!num_unmatched)
   		return;
  -	for (i = 0; i < istate->cache_nr; i++) {
  +	for (unsigned int i = 0; i < istate->cache_nr; i++) {
   		const struct cache_entry *ce = istate->cache[i];
   		if (sw_action == PS_IGNORE_SKIP_WORKTREE &&
   		    (ce_skip_worktree(ce) || !path_in_sparse_checkout(ce->name, istate)))

This would read much cleaner and also avoid two different loop
variables. WDYT?

We could certainly do that. My impression was that the convention was
not to do so.

Also a bigger question is, shouldn't the type of `pathspec.nr` and
'istate.cache_nr' be the actual change required? Shouldn't they be set
to 'size_t'?

I tried that first and found that it required making a large number of
changes spread over many files. As noted in my commit message, both
signed and unsigned types are used at different places for this
purpose.

quoted

@@ -78,7 +78,7 @@ char *find_pathspecs_matching_skip_worktree(const struct pathspec *pathspec)
 {
 	struct index_state *istate = the_repository->index;
 	char *seen = xcalloc(pathspec->nr, 1);
-	int i;
+	unsigned int i;

Nit: We could also drop this and move the initialization to the line
below.

quoted

 	for (i = 0; i < istate->cache_nr; i++) {
 		struct cache_entry *ce = istate->cache[i];

@@ -130,7 +130,7 @@ static void prefix_magic(struct strbuf *sb, int prefixlen,
 	if (element[1] != '(') {
 		/* Process an element in shorthand form (e.g. ":!/<match>") */
 		strbuf_addstr(sb, ":(");
-		for (int i = 0; i < ARRAY_SIZE(pathspec_magic); i++) {
+		for (unsigned int i = 0; i < ARRAY_SIZE(pathspec_magic); i++) {
 			if ((magic & pathspec_magic[i].bit) &&
 			    pathspec_magic[i].mnemonic) {
 				if (sb->buf[sb->len - 1] != '(')

Shouldn't we use 'size_t' for this, since we're iterating over the
elements of an array?

We can use size_t there.

quoted

@@ -341,7 +341,7 @@ static const char *parse_long_magic(unsigned *magic, int *prefix_len,

 	for (pos = elem + 2; *pos && *pos != ')'; pos = nextat) {
 		size_t len = strcspn_escaped(pos, ",)");
-		int i;
+		unsigned int i;

This too should be 'size_t'.

quoted

 		if (pos[len] == ',')
 			nextat = pos + len + 1; /* handle ',' */

@@ -354,7 +354,7 @@ static const char *parse_long_magic(unsigned *magic, int *prefix_len,
 		if (starts_with(pos, "prefix:")) {
 			char *endptr;
 			*prefix_len = strtol(pos + 7, &endptr, 10);
-			if (endptr - pos != len)
+			if ((size_t)(endptr - pos) != len)
 				die(_("invalid parameter for pathspec magic 'prefix'"));
 			continue;
 		}

This makes sense. But is it guaranteed that `endptr - pos` is greater
than 0?

endptr - pos will be greater than or equal to zero, as endptr is set by
strtol

quoted

@@ -400,7 +400,7 @@ static const char *parse_short_magic(unsigned *magic, const char *elem)

 	for (pos = elem + 1; *pos && *pos != ':'; pos++) {
 		char ch = *pos;
-		int i;
+		unsigned int i;

This too, should be 'size_t'

quoted

 		/* Special case alias for '!' */
 		if (ch == '^') {

@@ -564,7 +564,7 @@ static int pathspec_item_cmp(const void *a_, const void *b_)

 void pathspec_magic_names(unsigned magic, struct strbuf *out)
 {
-	int i;
+	unsigned int i;

This can be inlined and made 'size_t'.

quoted

 	for (i = 0; i < ARRAY_SIZE(pathspec_magic); i++) {
 		const struct pathspec_magic *m = pathspec_magic + i;
 		if (!(magic & m->bit))

@@ -803,8 +803,8 @@ int match_pathspec_attrs(struct index_state *istate,
 int pathspec_needs_expanded_index(struct index_state *istate,
 				  const struct pathspec *pathspec)
 {
-	unsigned int i, pos;
-	int res = 0;
+	unsigned int pos;
+	int i, res = 0;
 	char *skip_worktree_seen = NULL;

This can be inlined, but this change is done to match 'pathspec.nr''s
type. This goes to my earlier question, I would say we first need to
modify 'pathspec.nr' itself to be 'size_t'.

quoted

 	/*

@@ -845,7 +845,7 @@ int pathspec_needs_expanded_index(struct index_state *istate,
 			 * - not-in-cone/bar*: may need expanded index
 			 * - **.c: may need expanded index
 			 */
-			if (strspn(item.original + item.nowildcard_len, "*") == item.len - item.nowildcard_len &&
+			if (strspn(item.original + item.nowildcard_len, "*") == (unsigned int)(item.len - item.nowildcard_len) &&
 			    path_in_cone_mode_sparse_checkout(item.original, istate))
 				continue;

Similar here, I see the types of 'item.len' and 'item.nowwildcard_len'
are 'int'. Do they need to be 'size_t'?

Same as above, will require a large number of changes.
 

quoted

@@ -860,7 +860,7 @@ int pathspec_needs_expanded_index(struct index_state *istate,
 				 * directory name and the sparse directory is the first
 				 * component of the pathspec, need to expand the index.
 				 */
-				if (item.nowildcard_len > ce_namelen(ce) &&
+				if ((unsigned int)item.nowildcard_len > ce_namelen(ce) &&
 				    !strncmp(item.original, ce->name, ce_namelen(ce))) {
 					res = 1;
 					break;
--

2.48.1

Same question as above!

-- 
Regards,
Arnav Bhate
(He/Him)