Re: [PATCH v3 5/8] evolve: Add the change-table structure

From

Johannes Schindelin <johannes.schindelin@gmx.de>

Date

Jan 28, 2019, 23:08 UTC

Message-ID

<nycvar.QRO.7.76.6.1901290005390.41@tvgsbejvaqbjf.bet>

In-Reply-To

<nycvar.QRO.7.76.6.1901280858060.41@tvgsbejvaqbjf.bet>

Hi Junio,

On Mon, 28 Jan 2019, Johannes Schindelin wrote:

> On Sun, 27 Jan 2019, sxenos@google.com wrote:
> 
> > +	new_item->util = (void*)index;
> 
> This is not good. You are using a `long` here. The 80s called and want
> their now-obsolete data types back.
> 
> If you want a data type that can take an integer but also a pointer, use
> `intptr_t` instead.
> 
> But even that is not good practice. What you really want here is to use a
> union of the data types that you want to store in that `util` field.
> 
> This is not merely academic, your code causes compile errors on Windows:
> 
> https://dev.azure.com/gitgitgadget/git/_build/results?buildId=400&view=logs&jobId=fd490c07-0b22-5182-fac9-6d67fe1e939b&taskId=ce91d5d6-0c55-50f5-8ab9-6695c03ab102&lineStart=430&lineEnd=440&colStart=1&colEnd=1

-- snipsnap --

diff --git a/change-table.c b/change-table.c
index 2e0d935de846..197ce2783532 100644
--- a/change-table.c
+++ b/change-table.c
@@ -103,7 +103,7 @@ void change_table_add(struct change_table *to_modify, const char *refname,
 	new_head->hidden = starts_with(refname, "refs/hiddenmetas/");
 
 	new_item = string_list_insert(&to_modify->refname_to_change_head, refname);
-	new_item->util = (void*)index;
+	new_item->util = (void *)(intptr_t)index;
 	// Use pointers to the copy of the string we're retaining locally
 	refname = new_item->string;
 
@@ -201,6 +201,6 @@ struct change_head* get_change_head(struct change_table *heads,
 		return NULL;
 	}
 
-	index = (long)item->util;
+	index = (long)(intptr_t)item->util;
 	return &(heads->heads.array[index]);
 }