Re: [PATCH 3/3] builtin/checkout--worker: memset struct to avoid MSAN complaints

Chris Torek [off-list ref] writes:

On Thu, Jun 10, 2021 at 9:49 AM Andrzej Hunt via GitGitGadget
[off-list ref] wrote:

quoted

[snip] Therefore we add a
memset to convince MSAN that this memory is safe to read - but only
when building with MSAN to avoid this cost in normal usage.

It does not seem likely to be that expensive, and would definitely
be shorter without all the `#if` testing:

quoted

diff --git a/builtin/checkout--worker.c b/builtin/checkout--worker.c
index 289a9b8f89d0..02fa5285988f 100644
--- a/builtin/checkout--worker.c
+++ b/builtin/checkout--worker.c

@@ -56,6 +56,17 @@ static void report_result(struct parallel_checkout_item *pc_item)
        struct pc_item_result res;

This could just have `= { 0 }` added.

I'd prefer that very much more than the #if testing, within which //
comments that we do not want in our codebase are enclosed.

Thanks.

On 11/06/2021 08:28, Junio C Hamano wrote:

Chris Torek [off-list ref] writes:

quoted

On Thu, Jun 10, 2021 at 9:49 AM Andrzej Hunt via GitGitGadget
[off-list ref] wrote:

quoted

[snip] Therefore we add a
memset to convince MSAN that this memory is safe to read - but only
when building with MSAN to avoid this cost in normal usage.

It does not seem likely to be that expensive, and would definitely
be shorter without all the `#if` testing:

quoted

diff --git a/builtin/checkout--worker.c b/builtin/checkout--worker.c
index 289a9b8f89d0..02fa5285988f 100644
--- a/builtin/checkout--worker.c
+++ b/builtin/checkout--worker.c

@@ -56,6 +56,17 @@ static void report_result(struct parallel_checkout_item *pc_item)
         struct pc_item_result res;

This could just have `= { 0 }` added.

I'd prefer that very much more than the #if testing, within which //
comments that we do not want in our codebase are enclosed.

I'll fix this for V2 - thanks Chris and Junio!

(At the time I wasn't aware that this would include all members and 
padding, but I've learned more since reading the clang developer's 
discussion around padding and brace intialisation :) : 
https://reviews.llvm.org/D61280 . )