Correctly handle (?i) in ignores (fixes #1953)

lib/fnmatch/fnmatch.go

@@ -38,14 +38,6 @@ func Convert(pattern string, flags int) (*regexp.Regexp, error) {
 		}
 	}
 
-	// Support case insensitive ignores. We do the loop because we may in some
-	// circumstances end up with multiple insensitivity prefixes
-	// ("(?i)(?i)foo"), which should be accepted.
-	for ignore := strings.TrimPrefix(pattern, "(?i)"); ignore != pattern; ignore = strings.TrimPrefix(pattern, "(?i)") {
-		flags |= CaseFold
-		pattern = ignore
-	}
-
 	if flags&NoEscape != 0 {
 		pattern = strings.Replace(pattern, "\\", "\\\\", -1)
 	} else {

lib/fnmatch/fnmatch_test.go

@@ -53,10 +53,6 @@ var testcases = []testcase{
 	{"**/foo.txt", "bar/baz/foo.txt", PathName, true},
 
 	{"foo.txt", "foo.TXT", CaseFold, true},
-	{"(?i)foo.txt", "foo.TXT", 0, true},
-	{"(?i)(?i)foo.txt", "foo.TXT", 0, true}, // repeated prefix should be fine
-	{"(?i)**foo.txt", "/dev/tmp/foo.TXT", 0, true},
-	{"(?i)!**foo.txt", "/dev/tmp/foo.TXT", 0, false},
 
 	// These characters are literals in glob, but not in regexp.
 	{"hey$hello", "hey$hello", 0, true},

lib/ignore/ignore.go

@@ -206,22 +206,28 @@ func parseIgnoreFile(fd io.Reader, currentFile string, seen map[string]bool) ([]
 			include = false
 		}
 
+		flags := fnmatch.PathName
+		if strings.HasPrefix(line, "(?i)") {
+			line = line[4:]
+			flags |= fnmatch.CaseFold
+		}
+
 		if strings.HasPrefix(line, "/") {
 			// Pattern is rooted in the current dir only
-			exp, err := fnmatch.Convert(line[1:], fnmatch.PathName)
+			exp, err := fnmatch.Convert(line[1:], flags)
 			if err != nil {
 				return fmt.Errorf("Invalid pattern %q in ignore file", line)
 			}
 			patterns = append(patterns, Pattern{exp, include})
 		} else if strings.HasPrefix(line, "**/") {
 			// Add the pattern as is, and without **/ so it matches in current dir
-			exp, err := fnmatch.Convert(line, fnmatch.PathName)
+			exp, err := fnmatch.Convert(line, flags)
 			if err != nil {
 				return fmt.Errorf("Invalid pattern %q in ignore file", line)
 			}
 			patterns = append(patterns, Pattern{exp, include})
 
-			exp, err = fnmatch.Convert(line[3:], fnmatch.PathName)
+			exp, err = fnmatch.Convert(line[3:], flags)
 			if err != nil {
 				return fmt.Errorf("Invalid pattern %q in ignore file", line)
 			}
@@ -236,13 +242,13 @@ func parseIgnoreFile(fd io.Reader, currentFile string, seen map[string]bool) ([]
 		} else {
 			// Path name or pattern, add it so it matches files both in
 			// current directory and subdirs.
-			exp, err := fnmatch.Convert(line, fnmatch.PathName)
+			exp, err := fnmatch.Convert(line, flags)
 			if err != nil {
 				return fmt.Errorf("Invalid pattern %q in ignore file", line)
 			}
 			patterns = append(patterns, Pattern{exp, include})
 
-			exp, err = fnmatch.Convert("**/"+line, fnmatch.PathName)
+			exp, err = fnmatch.Convert("**/"+line, flags)
 			if err != nil {
 				return fmt.Errorf("Invalid pattern %q in ignore file", line)
 			}