index-pack: test and document --strict=<msg-id>=<severity>...

5d477a334a (fsck (receive-pack): allow demoting errors to warnings,
2015-06-22) allowed a list of fsck msg to downgrade to be passed to
--strict. However this is a hidden argument that was not documented nor
tested. Though it is true that most users would not call this option
directly, (nor use index-pack for that matter) it is still useful to
document and test this feature.

Reviewed-by: Christian Couder <christian.couder@gmail.com>
Signed-off-by: John Cai <johncai86@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-index-pack.txt

@@ -79,8 +79,13 @@ OPTIONS
 	to force the version for the generated pack index, and to force
 	64-bit index entries on objects located above the given offset.
 
---strict::
-	Die, if the pack contains broken objects or links.
+--strict[=<msg-id>=<severity>...]::
+	Die, if the pack contains broken objects or links. An optional
+	comma-separated list of `<msg-id>=<severity>` can be passed to change
+	the severity of some possible issues, e.g.,
+	 `--strict="missingEmail=ignore,badTagName=error"`. See the entry for the
+	`fsck.<msg-id>` configuration options in linkgit:git-fsck[1] for more
+	information on the possible values of `<msg-id>` and `<severity>`.
 
 --progress-title::
 	For internal use only.

builtin/index-pack.c

@@ -26,7 +26,7 @@
 #include "setup.h"
 
 static const char index_pack_usage[] =
-"git index-pack [-v] [-o <index-file>] [--keep | --keep=<msg>] [--[no-]rev-index] [--verify] [--strict] (<pack-file> | --stdin [--fix-thin] [<pack-file>])";
+"git index-pack [-v] [-o <index-file>] [--keep | --keep=<msg>] [--[no-]rev-index] [--verify] [--strict[=<msg-id>=<severity>...]] (<pack-file> | --stdin [--fix-thin] [<pack-file>])";
 
 struct object_entry {
 	struct pack_idx_entry idx;

t/t5300-pack-object.sh

@@ -441,6 +441,28 @@ test_expect_success 'index-pack with --strict' '
 	)
 '
 
+test_expect_success 'index-pack with --strict downgrading fsck msgs' '
+	test_when_finished rm -rf strict &&
+	git init strict &&
+	(
+		cd strict &&
+		test_commit first hello &&
+		cat >commit <<-EOF &&
+		tree $(git rev-parse HEAD^{tree})
+		parent $(git rev-parse HEAD)
+		author A U Thor
+		committer A U Thor
+
+		commit: this is a commit with bad emails
+
+		EOF
+		git hash-object --literally -t commit -w --stdin <commit >commit_list &&
+		PACK=$(git pack-objects test <commit_list) &&
+		test_must_fail git index-pack --strict "test-$PACK.pack" &&
+		git index-pack --strict="missingEmail=ignore" "test-$PACK.pack"
+	)
+'
+
 test_expect_success 'honor pack.packSizeLimit' '
 	git config pack.packSizeLimit 3m &&
 	packname_10=$(git pack-objects test-10 <obj-list) &&