Re: [PATCH 31/32] commit-graph.c: fix code that could convert the result of an integer multiplication to a larger type
- From
Johannes Schindelin <johannes.schindelin@gmx.de>
- Date
- Nov 7, 2019, 12:45 UTC
- Message-ID
- <nycvar.QRO.7.76.6.1911071344050.46@tvgsbejvaqbjf.bet>
- In-Reply-To
- <20191107022347.GE6351@danh.dev>
Hi Danh,
On Thu, 7 Nov 2019, Danh Doan wrote:
Show 15 quoted lines
> On 2019-11-06 11:23:00 +0900, Junio C Hamano wrote: > > > @@ -1454,7 +1454,7 @@ static int write_commit_graph_file(struct write_commit_graph_context *ctx) > > > num_chunks); > > > ctx->progress = start_delayed_progress( > > > progress_title.buf, > > > - num_chunks * ctx->commits.nr); > > > + (uint64_t)num_chunks * ctx->commits.nr); > > > > Hmph, do we need this? I understand that the second parameter to > > the callee is u64, so the caller needs to come up with u64 without > > overflow, but doesn't that automatically get promoted? > > Neither num_chunks nor ctx->commits.nr is promoted because both of > them are int. The result of `num_chunks * ctx->commits.nr' will be int > and will be promoted to u64 to pass to caller.
If you up-cast, maybe do the second operand so that nobody has to spend cycles trying to remember whether the cast or the arithmetic operand bind stronger? I.e. `num_chunks * (uint64_t)ctx->commits.nr`.
Ciao, Dscho