[RFC PATCH v1] pathspec: warn: long and short forms are incompatible

["Σταύρος Ντέντος" <stdedos@gmail.com>]

From: Stavros Ntentos <133706+stdedos@users.noreply.github.com>

Namely, `!` and any other long magic form (e.g. `glob`)
cannot be combined to one entry.

Issue a warning when such thing happens, and hint to the solution.

Signed-off-by: Stavros Ntentos <133706+stdedos@users.noreply.github.com>
---
 pathspec.c                  | 24 ++++++++++++++++++++++++
 pathspec.h                  |  1 +
 t/t6132-pathspec-exclude.sh | 33 +++++++++++++++++++++++++++++++++
 3 files changed, 58 insertions(+)

diff --git a/pathspec.c b/pathspec.c
index 7a229d8d22..4ac8bfdc06 100644
--- a/pathspec.c
+++ b/pathspec.c
@@ -1,3 +1,5 @@
+#include <stdio.h>
+#include <string.h>
 #include "cache.h"
 #include "config.h"
 #include "dir.h"
@@ -5,6 +7,7 @@
 #include "attr.h"
 #include "strvec.h"
 #include "quote.h"
+#include "git-compat-util.h"
 
 /*
  * Finds which of the given pathspecs match items in the index.
@@ -586,6 +589,8 @@ void parse_pathspec(struct pathspec *pathspec,
 	for (i = 0; i < n; i++) {
 		entry = argv[i];
 
+		check_mishandled_exclude(entry);
+
 		init_pathspec_item(item + i, flags, prefix, prefixlen, entry);
 
 		if (item[i].magic & PATHSPEC_EXCLUDE)
@@ -739,3 +744,22 @@ int match_pathspec_attrs(const struct index_state *istate,
 
 	return 1;
 }
+
+void check_mishandled_exclude(const char *entry) {
+	char *flags, *path;
+	size_t entry_len = strlen(entry);
+
+	flags = xstrdup(entry);
+	memset(flags, '\0', entry_len);
+	path = xstrdup(entry);
+	memset(path, '\0', entry_len);
+
+	if (sscanf(entry, ":!(%4096[^)])%4096s", flags, path) == 2) {
+		if (count_slashes(flags) == 0) {
+			warning(_("Pathspec provided matches `:!(...)`\n\tDid you mean `:(exclude,...)`?"));
+		}
+	}
+
+	FREE_AND_NULL(flags);
+	FREE_AND_NULL(path);
+}
diff --git a/pathspec.h b/pathspec.h
index 454ce364fa..879d4e82c6 100644
--- a/pathspec.h
+++ b/pathspec.h
@@ -157,5 +157,6 @@ char *find_pathspecs_matching_against_index(const struct pathspec *pathspec,
 int match_pathspec_attrs(const struct index_state *istate,
 			 const char *name, int namelen,
 			 const struct pathspec_item *item);
+void check_mishandled_exclude(const char* pathspec_entry);
 
 #endif /* PATHSPEC_H */
diff --git a/t/t6132-pathspec-exclude.sh b/t/t6132-pathspec-exclude.sh
index 30328b87f0..b32ddb2a56 100755
--- a/t/t6132-pathspec-exclude.sh
+++ b/t/t6132-pathspec-exclude.sh
@@ -244,4 +244,37 @@ test_expect_success 'grep --untracked PATTERN :(exclude)*FILE' '
 	test_cmp expect-grep actual-grep
 '
 
+cat > expected_warn <<"EOF"
+Pathspec provided matches `:!(...)`
+EOF
+test_expect_success 'warn pathspec :!(...) skips the parenthesized magics' '
+	git log --oneline --format=%s -- '"'"':!(glob)**/file'"'"' >actual 2>warn &&
+	cat <<EOF >expect &&
+sub2/file
+sub/sub/sub/file
+sub/file2
+sub/sub/file
+sub/file
+file
+EOF
+	cat actual &&
+	cat warn &&
+	test_cmp expect actual &&
+	grep -Ff expected_warn warn
+'
+
+test_expect_success 'do not warn that pathspec :!(...) skips the parenthesized magics (if parenthesis would not be part of the magic)' '
+	git log --oneline --format=%s -- '"'"':!(gl/ob)/file'"'"' >actual 2>warn &&
+	cat <<EOF >expect &&
+sub2/file
+sub/sub/sub/file
+sub/file2
+sub/sub/file
+sub/file
+file
+EOF
+	test_cmp expect actual &&
+	! grep -Ff expected_warn warn
+'
+
 test_done
-- 
2.31.0