Remove redundant double exclamation points

From: Seija Kijin <[email protected]>

S_ISDIR is a macro that involves a "==" comparison.

This means the !! is redundant and not needed.

---
Remove redundant double exclamation points

S_ISDIR is a macro that involves a "==" comparison.

This means the !! is redundant and not needed.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-1401%2FAtariDreams%2FIS_DIR-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-1401/AtariDreams/IS_DIR-v1
Pull-Request: https://github.com/git/git/pull/1401

 tree-walk.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

index 74f4d710e8f..6b51d27ccb2 100644
@@ -1040,9 +1040,9 @@ static enum interesting do_match(struct index_state *istate,
 		    ps->max_depth == -1)
 			return all_entries_interesting;
 		return within_depth(base->buf + base_offset, baselen,
-				    !!S_ISDIR(entry->mode),
-				    ps->max_depth) ?
-			entry_interesting : entry_not_interesting;
+				    S_ISDIR(entry->mode), ps->max_depth) ?
+			       entry_interesting :
+			       entry_not_interesting;
 	}
 
 	pathlen = tree_entry_len(entry);

@@ -1073,8 +1073,7 @@ static enum interesting do_match(struct index_state *istate,
 
 			if (within_depth(base_str + matchlen + 1,
 					 baselen - matchlen - 1,
-					 !!S_ISDIR(entry->mode),
-					 ps->max_depth))
+					 S_ISDIR(entry->mode), ps->max_depth))
 				goto interesting;
 			else
 				return entry_not_interesting;

base-commit: 7c2ef319c52c4997256f5807564523dfd4acdfc7

gitgitgadget

It does? The POSIX standard
(https://pubs.opengroup.org/onlinepubs/009604499/basedefs/sys/stat.h.html)
says:

The following macros shall be provided to test whether a file is of the specified type. The value m supplied to the macros is the value of st_mode from a stat structure. The macro shall evaluate to a non-zero value if the test is true; 0 if the test is false.

The "non-zero" there seems to intentionally leave open that this may be defined e.g. as via a "&" test, as opposed to "==" which according to C99's 6.5.9.3 says:

The == (equal to) and != (not equal to) operators are analogous to the relational operators except for their lower precedence.90) Each of the operators yields 1 if the specified relation is true and 0 if it is false. The result has type int. For any pair of operands, exactly one of the relations is true.

I think you're therefore introducing a bug here, this may work on your platform, but we have no guarantee that it'll work elsewhere.

I thought that it probably wouldn't matter, as we'd treat the argument as a boolean, but we don't. In within_depth() we proceed to use the passed-in 3rd argument (depth) as a counter, so it really does matter if it's 0, 1, or other non-zero.

	@@
	@@
	- !!
	(
	S_ISDIR
	|
	S_ISFIFO
        // |
        // we'd continue to list the rest here...
	)
	  (...)

Thanks, well analysed.