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From: Simon Marchi <>
To: Tom Tromey <>,
Subject: Re: [PATCH v2] Fix comparator bug in cooked index
Date: Mon, 30 Jan 2023 10:15:45 -0500	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On 1/30/23 09:56, Tom Tromey via Gdb-patches wrote:
> Simon pointed out that the cooked index template-matching patch
> introduced a failure in libstdc++ debug mode.  In particular, the new
> code violates the assumption of std::lower_bound and std::upper_bound
> that the range is sorted with respect to the comparison.
> When I first debugged this, I thought the problem was unfixable as-is
> and that a second layer of filtering would have to be done.  However,
> on irc, Simon pointed out that it could perhaps be solved if the
> comparison function were assured that one operand always came from the
> index, with the other always being the search string.
> This patch implements this idea.
> First, a new mode is introduced: a sorting mode for
> cooked_index_entry::compare.  In this mode, strings are compared
> case-insensitively, but we're careful to always sort '<' before any
> other printable character.  This way, two names like "func" and
> "func<param>" will be sorted next to each other -- i.e., "func1" will
> not be seen between them.  This is important when searching.
> Second, the compare function is changed to work in a strcmp-like way.
> This makes it easier to test and (IMO) understand.
> Third, the compare function is modified so that in non-sorting modes,
> the index entry is always the first argument.  This allows consistency
> in compares.
> I regression tested this in libstdc++ debug mode on x86-64 Fedora 36.
> It fixes the crash that Simon saw.
> This is v2.  I believe it addresses the review comments, except for
> the 'enum class' change, as I mentioned in email on the list.

This LGTM:

Approved-By: Simon Marchi <>


  reply	other threads:[~2023-01-30 15:15 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-30 14:56 Tom Tromey
2023-01-30 15:15 ` Simon Marchi [this message]
2023-01-30 17:46   ` Tom Tromey

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