commit: print advice when core.commentString=auto

Add some advice on how to change the config settings when
"core.commentString=auto" or "core.commentChar=auto". The advice
includes instructions for clearing the config setting or setting a
fixed comment string. To try and be as specific as possible, the advice
is customized based on the user's config. If "core.commentString=auto"
is set in the system config and the user does not have write
access then the advice omits the instructions to clear the config
and recommends changing the global config instead. An alternative
approach would be to advise the user to run "git config --show-origin"
and leave them to figure out how to fix it themselves but that seems
rather unfriendly. As we're forcing them to update their config we
should try and make that as easy as possible.

In order to generate this advice we need to record each file where
either of the config keys is set and whether a key occurs more that
once in a given file. This lets us generate the list of commands to
remove all the keys and also tells us which key the "auto" setting
comes from.

As we want the user to update their config we do not provide a way
for this advice to be disabled other than changing the value of
"core.commentChar" or "core.commentString".

Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

2 files changed, 45 insertions, 4 deletions

diff --git a/t/t3404-rebase-interactive.sh b/t/t3404-rebase-interactive.sh
index 3b2a46c25c..cc97628d81 100755
--- a/t/t3404-rebase-interactive.sh
+++ b/t/t3404-rebase-interactive.sh
@@ -1186,9 +1186,19 @@ test_expect_success !WITH_BREAKING_CHANGES 'rebase -i respects core.commentchar=
 		test_set_editor "$(pwd)/copy-edit-script.sh" &&
 		git rebase -i HEAD^ 2>err
 	) &&
-	sed -n "s/^warning: //p" err >actual &&
+	sed -n "s/^hint: *\$//p; s/^hint: //p; s/^warning: //p" err >actual &&
 	cat >expect <<-EOF &&
 	Support for ${SQ}core.commentChar=auto${SQ} is deprecated and will be removed in Git 3.0
+
+	To use the default comment string (#) please run
+
+	    git config unset core.commentChar
+
+	To set a custom comment string please run
+
+	    git config set core.commentChar <comment string>
+
+	where ${SQ}<comment string>${SQ} is the string you wish to use.
 	EOF
 	test_cmp expect actual &&
 	test -z "$(grep -ve "^#" -e "^\$" -e "^pick" edit-script)"
diff --git a/t/t7502-commit-porcelain.sh b/t/t7502-commit-porcelain.sh
index a9dc1e416d..05f6da4ad9 100755
--- a/t/t7502-commit-porcelain.sh
+++ b/t/t7502-commit-porcelain.sh
@@ -958,10 +958,31 @@ test_expect_success 'commit --status with custom comment character' '
 
 test_expect_success !WITH_BREAKING_CHANGES 'switch core.commentchar' '
 	test_commit "#foo" foo &&
-	GIT_EDITOR=.git/FAKE_EDITOR git -c core.commentChar=auto commit --amend 2>err &&
-	sed -n "s/^warning: //p" err >actual &&
+	cat >config-include <<-\EOF &&
+	[core]
+	    commentString=:
+	    commentString=%
+	    commentChar=auto
+	EOF
+	test_when_finished "rm config-include" &&
+	test_config include.path "$(pwd)/config-include" &&
+	test_config core.commentChar ! &&
+	GIT_EDITOR=.git/FAKE_EDITOR git commit --amend 2>err &&
+	sed -n "s/^hint: *\$//p; s/^hint: //p; s/^warning: //p" err >actual &&
 	cat >expect <<-EOF &&
 	Support for ${SQ}core.commentChar=auto${SQ} is deprecated and will be removed in Git 3.0
+
+	To use the default comment string (#) please run
+
+	    git config unset core.commentChar
+	    git config unset --file ~/config-include --all core.commentString
+	    git config unset --file ~/config-include core.commentChar
+
+	To set a custom comment string please run
+
+	    git config set --file ~/config-include core.commentChar <comment string>
+
+	where ${SQ}<comment string>${SQ} is the string you wish to use.
 	EOF
 	test_cmp expect actual &&
 	test_grep "^; Changes to be committed:" .git/COMMIT_EDITMSG
@@ -990,9 +1011,19 @@ EOF
 test_expect_success WITH_BREAKING_CHANGES 'core.commentChar=auto is rejected' '
 	test_config core.commentChar auto &&
 	test_must_fail git rev-parse --git-dir 2>err &&
-	sed -n "s/^fatal: //p" err >actual &&
+	sed -n "s/^hint: *\$//p; s/^hint: //p; s/^fatal: //p" err >actual &&
 	cat >expect <<-EOF &&
 	Support for ${SQ}core.commentChar=auto${SQ} has been removed in Git 3.0
+
+	To use the default comment string (#) please run
+
+	    git config unset core.commentChar
+
+	To set a custom comment string please run
+
+	    git config set core.commentChar <comment string>
+
+	where ${SQ}<comment string>${SQ} is the string you wish to use.
 	EOF
 	test_cmp expect actual
 '