Merge branch 'nd/exclusion-regression-fix' into maint

The ignore mechanism saw a few regressions around untracked file
listing and sparse checkout selection areas in 2.7.0; the change
that is responsible for the regression has been reverted.

* nd/exclusion-regression-fix:
  Revert "dir.c: don't exclude whole dir prematurely if neg pattern may match"

Documentation/gitignore.txt

@@ -82,12 +82,12 @@ PATTERN FORMAT
 
  - An optional prefix "`!`" which negates the pattern; any
    matching file excluded by a previous pattern will become
-   included again.
+   included again. It is not possible to re-include a file if a parent
+   directory of that file is excluded. Git doesn't list excluded
+   directories for performance reasons, so any patterns on contained
+   files have no effect, no matter where they are defined.
    Put a backslash ("`\`") in front of the first "`!`" for patterns
    that begin with a literal "`!`", for example, "`\!important!.txt`".
-   It is possible to re-include a file if a parent directory of that
-   file is excluded if certain conditions are met. See section NOTES
-   for detail.
 
  - If the pattern ends with a slash, it is removed for the
    purpose of the following description, but it would only find
@@ -141,21 +141,6 @@ not tracked by Git remain untracked.
 To stop tracking a file that is currently tracked, use
 'git rm --cached'.
 
-To re-include files or directories when their parent directory is
-excluded, the following conditions must be met:
-
- - The rules to exclude a directory and re-include a subset back must
-   be in the same .gitignore file.
-
- - The directory part in the re-include rules must be literal (i.e. no
-   wildcards)
-
- - The rules to exclude the parent directory must not end with a
-   trailing slash.
-
- - The rules to exclude the parent directory must have at least one
-   slash.
-
 EXAMPLES
 --------
 

dir.c

@@ -880,25 +880,6 @@ int match_pathname(const char *pathname, int pathlen,
 		 */
 		if (!patternlen && !namelen)
 			return 1;
-		/*
-		 * This can happen when we ignore some exclude rules
-		 * on directories in other to see if negative rules
-		 * may match. E.g.
-		 *
-		 * /abc
-		 * !/abc/def/ghi
-		 *
-		 * The pattern of interest is "/abc". On the first
-		 * try, we should match path "abc" with this pattern
-		 * in the "if" statement right above, but the caller
-		 * ignores it.
-		 *
-		 * On the second try with paths within "abc",
-		 * e.g. "abc/xyz", we come here and try to match it
-		 * with "/abc".
-		 */
-		if (!patternlen && namelen && *name == '/')
-			return 1;
 	}
 
 	return fnmatch_icase_mem(pattern, patternlen,
@@ -906,48 +887,6 @@ int match_pathname(const char *pathname, int pathlen,
 				 WM_PATHNAME) == 0;
 }
 
-/*
- * Return non-zero if pathname is a directory and an ancestor of the
- * literal path in a (negative) pattern. This is used to keep
- * descending in "foo" and "foo/bar" when the pattern is
- * "!foo/bar/.gitignore". "foo/notbar" will not be descended however.
- */
-static int match_neg_path(const char *pathname, int pathlen, int *dtype,
-			  const char *base, int baselen,
-			  const char *pattern, int prefix, int patternlen,
-			  int flags)
-{
-	assert((flags & EXC_FLAG_NEGATIVE) && !(flags & EXC_FLAG_NODIR));
-
-	if (*dtype == DT_UNKNOWN)
-		*dtype = get_dtype(NULL, pathname, pathlen);
-	if (*dtype != DT_DIR)
-		return 0;
-
-	if (*pattern == '/') {
-		pattern++;
-		patternlen--;
-		prefix--;
-	}
-
-	if (baselen) {
-		if (((pathlen < baselen && base[pathlen] == '/') ||
-		     pathlen == baselen) &&
-		    !strncmp_icase(pathname, base, pathlen))
-			return 1;
-		pathname += baselen + 1;
-		pathlen  -= baselen + 1;
-	}
-
-
-	if (prefix &&
-	    ((pathlen < prefix && pattern[pathlen] == '/') &&
-	     !strncmp_icase(pathname, pattern, pathlen)))
-		return 1;
-
-	return 0;
-}
-
 /*
  * Scan the given exclude list in reverse to see whether pathname
  * should be ignored.  The first match (i.e. the last on the list), if
@@ -961,7 +900,7 @@ static struct exclude *last_exclude_matching_from_list(const char *pathname,
 						       struct exclude_list *el)
 {
 	struct exclude *exc = NULL; /* undecided */
-	int i, matched_negative_path = 0;
+	int i;
 
 	if (!el->nr)
 		return NULL;	/* undefined */
@@ -996,18 +935,7 @@ static struct exclude *last_exclude_matching_from_list(const char *pathname,
 			exc = x;
 			break;
 		}
-
-		if ((x->flags & EXC_FLAG_NEGATIVE) && !matched_negative_path &&
-		    match_neg_path(pathname, pathlen, dtype, x->base,
-				   x->baselen ? x->baselen - 1 : 0,
-				   exclude, prefix, x->patternlen, x->flags))
-			matched_negative_path = 1;
 	}
-	if (exc &&
-	    !(exc->flags & EXC_FLAG_NEGATIVE) &&
-	    !(exc->flags & EXC_FLAG_NODIR) &&
-	    matched_negative_path)
-		exc = NULL;
 	return exc;
 }
 

t/t3001-ls-files-others-exclude.sh

@@ -305,29 +305,4 @@ test_expect_success 'ls-files with "**" patterns and no slashes' '
 	test_cmp expect actual
 '
 
-test_expect_success 'negative patterns' '
-	git init reinclude &&
-	(
-		cd reinclude &&
-		cat >.gitignore <<-\EOF &&
-		/fooo
-		/foo
-		!foo/bar/bar
-		EOF
-		mkdir fooo &&
-		cat >fooo/.gitignore <<-\EOF &&
-		!/*
-		EOF
-		mkdir -p foo/bar &&
-		touch abc foo/def foo/bar/ghi foo/bar/bar &&
-		git ls-files -o --exclude-standard >../actual &&
-		cat >../expected <<-\EOF &&
-		.gitignore
-		abc
-		foo/bar/bar
-		EOF
-		test_cmp ../expected ../actual
-	)
-'
-
 test_done