Placing `struct lock_file`s on the stack used to be a bad idea, because
the temp- and lockfile-machinery would keep a pointer into the struct.
But after 076aa2cbd (tempfile: auto-allocate tempfiles on heap,
2017-09-05), we can safely have lockfiles on the stack. (This applies
even if a user returns early, leaving a locked lock behind.)

Each of these `struct lock_file`s is used from within a single function.
Move them into the respective functions to make the scope clearer and
drop the staticness.

For good measure, I have inspected these sites and come to believe that
they always release the lock, with the possible exception of bailing out
using `die()` or `exit()` or by returning from a `cmd_foo()`.

As pointed out by Jeff King, it would be bad if someone held on to a
`struct lock_file *` for some reason. After some grepping, I agree with
his findings: no-one appears to be doing that.

After this commit, the remaining occurrences of "static struct
lock_file" are locks that are used from within different functions. That
is, they need to remain static. (Short of more intrusive changes like
passing around pointers to non-static locks.)

Signed-off-by: Martin Ågren <martin.ag...@gmail.com>
---
 t/helper/test-scrap-cache-tree.c | 4 ++--
 builtin/add.c                    | 3 +--
 builtin/mv.c                     | 2 +-
 builtin/read-tree.c              | 3 +--
 builtin/rm.c                     | 3 +--
 rerere.c                         | 3 +--
 6 files changed, 7 insertions(+), 11 deletions(-)

diff --git a/t/helper/test-scrap-cache-tree.c b/t/helper/test-scrap-cache-tree.c
index d26d3e7c8b..393f1604ff 100644
--- a/t/helper/test-scrap-cache-tree.c
+++ b/t/helper/test-scrap-cache-tree.c
@@ -4,10 +4,10 @@
 #include "tree.h"
 #include "cache-tree.h"
 
-static struct lock_file index_lock;
-
 int cmd__scrap_cache_tree(int ac, const char **av)
 {
+       struct lock_file index_lock = LOCK_INIT;
+
        setup_git_directory();
        hold_locked_index(&index_lock, LOCK_DIE_ON_ERROR);
        if (read_cache() < 0)
diff --git a/builtin/add.c b/builtin/add.c
index c9e2619a9a..8a155dd41e 100644
--- a/builtin/add.c
+++ b/builtin/add.c
@@ -265,8 +265,6 @@ static int edit_patch(int argc, const char **argv, const 
char *prefix)
        return 0;
 }
 
-static struct lock_file lock_file;
-
 static const char ignore_error[] =
 N_("The following paths are ignored by one of your .gitignore files:\n");
 
@@ -393,6 +391,7 @@ int cmd_add(int argc, const char **argv, const char *prefix)
        int add_new_files;
        int require_pathspec;
        char *seen = NULL;
+       struct lock_file lock_file = LOCK_INIT;
 
        git_config(add_config, NULL);
 
diff --git a/builtin/mv.c b/builtin/mv.c
index 6d141f7a53..b4692409e3 100644
--- a/builtin/mv.c
+++ b/builtin/mv.c
@@ -72,7 +72,6 @@ static const char *add_slash(const char *path)
        return path;
 }
 
-static struct lock_file lock_file;
 #define SUBMODULE_WITH_GITDIR ((const char *)1)
 
 static void prepare_move_submodule(const char *src, int first,
@@ -131,6 +130,7 @@ int cmd_mv(int argc, const char **argv, const char *prefix)
        enum update_mode { BOTH = 0, WORKING_DIRECTORY, INDEX } *modes;
        struct stat st;
        struct string_list src_for_dst = STRING_LIST_INIT_NODUP;
+       struct lock_file lock_file = LOCK_INIT;
 
        git_config(git_default_config, NULL);
 
diff --git a/builtin/read-tree.c b/builtin/read-tree.c
index bf87a2710b..ebc43eb805 100644
--- a/builtin/read-tree.c
+++ b/builtin/read-tree.c
@@ -107,8 +107,6 @@ static int git_read_tree_config(const char *var, const char 
*value, void *cb)
        return git_default_config(var, value, cb);
 }
 
-static struct lock_file lock_file;
-
 int cmd_read_tree(int argc, const char **argv, const char *unused_prefix)
 {
        int i, stage = 0;
@@ -116,6 +114,7 @@ int cmd_read_tree(int argc, const char **argv, const char 
*unused_prefix)
        struct tree_desc t[MAX_UNPACK_TREES];
        struct unpack_trees_options opts;
        int prefix_set = 0;
+       struct lock_file lock_file = LOCK_INIT;
        const struct option read_tree_options[] = {
                { OPTION_CALLBACK, 0, "index-output", NULL, N_("file"),
                  N_("write resulting index to <file>"),
diff --git a/builtin/rm.c b/builtin/rm.c
index 5b6fc7ee81..65b448ef8e 100644
--- a/builtin/rm.c
+++ b/builtin/rm.c
@@ -233,8 +233,6 @@ static int check_local_mod(struct object_id *head, int 
index_only)
        return errs;
 }
 
-static struct lock_file lock_file;
-
 static int show_only = 0, force = 0, index_only = 0, recursive = 0, quiet = 0;
 static int ignore_unmatch = 0;
 
@@ -251,6 +249,7 @@ static struct option builtin_rm_options[] = {
 
 int cmd_rm(int argc, const char **argv, const char *prefix)
 {
+       struct lock_file lock_file = LOCK_INIT;
        int i;
        struct pathspec pathspec;
        char *seen;
diff --git a/rerere.c b/rerere.c
index 18cae2d11c..e0862e2778 100644
--- a/rerere.c
+++ b/rerere.c
@@ -703,10 +703,9 @@ static int merge(const struct rerere_id *id, const char 
*path)
        return ret;
 }
 
-static struct lock_file index_lock;
-
 static void update_paths(struct string_list *update)
 {
+       struct lock_file index_lock = LOCK_INIT;
        int i;
 
        hold_locked_index(&index_lock, LOCK_DIE_ON_ERROR);
-- 
2.17.0.411.g9fd64c8e46

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