From: Johannes Schindelin Date: Thu, 07 Nov 2019 12:45:23 GMT Subject: Re: [PATCH 31/32] commit-graph.c: fix code that could convert the result of an integer multiplication to a larger type Message-ID: In-Reply-To: <20191107022347.GE6351@danh.dev> Hi Danh, On Thu, 7 Nov 2019, Danh Doan wrote: > 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