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Re: [PATCH 0/3] yacc: compute the best type for the state number

From: Hans Åberg
Subject: Re: [PATCH 0/3] yacc: compute the best type for the state number
Date: Tue, 1 Oct 2019 15:53:09 +0200

> On 1 Oct 2019, at 10:35, Paul Eggert <address@hidden> wrote:
> In other GNU applications, we've been moving away from using unsigned types 
> due to their confusing behavior (particularly when comparing signed vs 
> unsigned), and because modern tools such as 'gcc -fsanitize=undefined' can 
> check for signed integer overflow but (obviously) not for unsigned integer 
> overflow. In this newer style, it's OK to use unsigned types for bit vectors 
> and hash values since these typically don't involve integer comparisons and 
> integer overflow is typically harmless; for indexes, though, unsigned types 
> are so error-prone that they should be avoided.

One should note that the unsigned types are required to be 2’s complement 
C/C++, unlike the signed ones, cf. [1]. Also, in C++, indices are required to 
be large enough to hold all values, so on 64-bit machines they are that also 
for strings that usually are quite small.


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