Re: /* compiler workaround */ - what was the issue?

["Philip Oakley" <philipoakley@iee.org>]

From: "Ramsay Jones" <ramsay@ramsayjones.plus.com>
> On 06/05/16 14:15, Philip Oakley wrote:
>> From: "Duy Nguyen" <pclouds@gmail.com>
>>> On Fri, May 6, 2016 at 4:41 AM, Junio C Hamano <gitster@pobox.com> 
>>> wrote:
>>>> "Philip Oakley" <philipoakley@iee.org> writes:
>>>>
>>>>>     int saved_namelen = saved_namelen; /* compiler workaround */
>>>>>
>>>>> Which then becomes an MSVC compile warning C4700: uninitialized local
>>>>> variable.
>>>>>
>>>>> I'm wondering what was the compiler workaround being referred to? i.e. 
>>>>> why
>>>>> does it need that tweak? There's no mention of the reason in the 
>>>>> commit
>>>>> message.
>>>>
>>>> That was a fairly well-known workaround for GCC that issues a false
>>>> warning that variable is used before initialized.  I thought we
>>>> stopped using it several years ago in new code after doing a bulk
>>>> sanitizing
>>>
>>> I guess that's 803a777 (cat-file: Fix an gcc -Wuninitialized warning -
>>> 2013-03-26) and more commits around that time. The split-index commit
>>> is in 2014. I must have missed the trend.
>>>
>>>> (I think the new recommended workaround was to initialise
>>>> such a variable to the nil value like '0' for integers).
>>>
>>> Yep. First Jeff removed the " = xxx" part from "xxx = xxx" then Ramsay
>>> added the " = NULL" back. So we probably just do "int saved_namelen =
>>> 0;" in this case.
>>> -- 
>> Thanks,
>>
>> I'll try and work up a patch - probably next week as I'm away for the 
>> weekend.
>
> Yeah, I don't remember why these were left over from the previous
> attempt to clean these up (maybe they conflicted with in-flight
> topics?), but I have had a patch hanging around ... :-D
>
> The patch below applies to master (I haven't checked for any more
> additions).

Looks good to me. Catches those I've seen.

Have a good weekend all.

>
> ATB,
> Ramsay Jones
>
> -- >8 --
> From: Ramsay Jones <ramsay@ramsayjones.plus.com>
> Subject: [PATCH] -Wuninitialized: remove a gcc specific workaround
>
> Signed-off-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
> ---
> builtin/rev-list.c | 2 +-
> fast-import.c      | 4 ++--
> merge-recursive.c  | 2 +-
> read-cache.c       | 2 +-
> 4 files changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/builtin/rev-list.c b/builtin/rev-list.c
> index 275da0d..deae1f3 100644
> --- a/builtin/rev-list.c
> +++ b/builtin/rev-list.c
> @@ -377,7 +377,7 @@ int cmd_rev_list(int argc, const char **argv, const 
> char *prefix)
>  mark_edges_uninteresting(&revs, show_edge);
>
>  if (bisect_list) {
> - int reaches = reaches, all = all;
> + int reaches = 0, all = 0;
>
>  revs.commits = find_bisection(revs.commits, &reaches, &all,
>        bisect_find_all);
> diff --git a/fast-import.c b/fast-import.c
> index 9fc7093..ca66d80 100644
> --- a/fast-import.c
> +++ b/fast-import.c
> @@ -2935,7 +2935,7 @@ static void cat_blob(struct object_entry *oe, 
> unsigned char sha1[20])
>
> static void parse_get_mark(const char *p)
> {
> - struct object_entry *oe = oe;
> + struct object_entry *oe = NULL;
>  char output[42];
>
>  /* get-mark SP <object> LF */
> @@ -2952,7 +2952,7 @@ static void parse_get_mark(const char *p)
>
> static void parse_cat_blob(const char *p)
> {
> - struct object_entry *oe = oe;
> + struct object_entry *oe = NULL;
>  unsigned char sha1[20];
>
>  /* cat-blob SP <object> LF */
> diff --git a/merge-recursive.c b/merge-recursive.c
> index 06d31ed..9cecc24 100644
> --- a/merge-recursive.c
> +++ b/merge-recursive.c
> @@ -1897,7 +1897,7 @@ int merge_recursive(struct merge_options *o,
> {
>  struct commit_list *iter;
>  struct commit *merged_common_ancestors;
> - struct tree *mrtree = mrtree;
> + struct tree *mrtree = NULL;
>  int clean;
>
>  if (show(o, 4)) {
> diff --git a/read-cache.c b/read-cache.c
> index d9fb78b..978d6b6 100644
> --- a/read-cache.c
> +++ b/read-cache.c
> @@ -1870,7 +1870,7 @@ static int ce_write_entry(git_SHA_CTX *c, int fd, 
> struct cache_entry *ce,
> {
>  int size;
>  struct ondisk_cache_entry *ondisk;
> - int saved_namelen = saved_namelen; /* compiler workaround */
> + int saved_namelen = 0;
>  char *name;
>  int result;
>
> -- 
> 2.8.0
> --
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