[PATCH 6/6] blame: enable funcname blaming with userdiff driver

["Philippe Blain via GitGitGadget" <gitgitgadget@gmail.com>]

From: Philippe Blain <levraiphilippeblain@gmail.com>

In blame.c::cmd_blame, we send the 'path' field of the 'sb' 'struct
blame_scoreboard' as the 'path' argument to
'line-range.c::parse_range_arg', but 'sb.path' is not set yet; it's set
to the local variable 'path' a few lines later at line 1137.

This 'path' argument is only used in 'parse_range_arg' if we are blaming
a funcname, i.e. `git blame -L :<funcname> <path>`, and in that case it
is sent to 'parse_range_funcname', where it is used to determine if a
userdiff driver should be used for said <path> to match the given
funcname.

Since 'path' is yet unset, the userdiff driver is never used, so we fall
back to the default funcname regex, which is usually not appropriate for
paths that are set to use a specific userdiff driver, and thus either we
match some unrelated lines, or we die with

    fatal: -L parameter '<funcname>' starting at line 1: no match

This has been the case ever since `git blame` learned to blame a
funcname in 13b8f68c1f (log -L: :pattern:file syntax to find by
funcname, 2013-03-28).

Enable funcname blaming for paths using specific userdiff drivers by
sending the local variable 'path' to 'parse_range_arg' instead of the
yet unset 'sb.path'.

Add a regression test in 'annotate-tests.sh', which is sourced in
t8001-annotate.sh and t8002-blame.sh, leveraging an existing file used
to test the userdiff patterns in t4018-diff-funcname.

Signed-off-by: Philippe Blain <levraiphilippeblain@gmail.com>
---
 builtin/blame.c     |  2 +-
 t/annotate-tests.sh | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/builtin/blame.c b/builtin/blame.c
index 05f69211dd..917fedc635 100644
--- a/builtin/blame.c
+++ b/builtin/blame.c
@@ -1104,7 +1104,7 @@ int cmd_blame(int argc, const char **argv, const char *prefix)
 		long bottom, top;
 		if (parse_range_arg(range_list.items[range_i].string,
 				    nth_line_cb, &sb, lno, anchor,
-				    &bottom, &top, sb.path,
+				    &bottom, &top, path,
 				    the_repository->index))
 			usage(blame_usage);
 		if ((!lno && (top || bottom)) || lno < bottom)
diff --git a/t/annotate-tests.sh b/t/annotate-tests.sh
index d933af5714..3aee61d2cc 100644
--- a/t/annotate-tests.sh
+++ b/t/annotate-tests.sh
@@ -479,6 +479,24 @@ test_expect_success 'blame -L ^:RE (absolute: end-of-file)' '
 	check_count -f hello.c -L$n -L^:ma.. F 4 G 1 H 1
 '
 
+test_expect_success 'setup -L :funcname with userdiff driver' '
+	echo "fortran-* diff=fortran" >.gitattributes &&
+	fortran_file=fortran-external-function &&
+	orig_file="$TEST_DIRECTORY/t4018/$fortran_file" &&
+	cp $orig_file . &&
+	git add $fortran_file &&
+	GIT_AUTHOR_NAME="A" GIT_AUTHOR_EMAIL="A@test.git" \
+	git commit -m "add fortran file" &&
+	sed -e "s/ChangeMe/IWasChanged/" <"$orig_file" >$fortran_file &&
+	git add $fortran_file &&
+	GIT_AUTHOR_NAME="B" GIT_AUTHOR_EMAIL="B@test.git" \
+	git commit -m "change fortran file"
+'
+
+test_expect_success 'blame -L :funcname with userdiff driver' '
+	check_count -f fortran-external-function -L:RIGHT A 7 B 1
+'
+
 test_expect_success 'setup incremental' '
 	(
 	GIT_AUTHOR_NAME=I &&
-- 
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