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bug#31688: 26.1.50; Byte compiler confuses two string variables
From: |
Noam Postavsky |
Subject: |
bug#31688: 26.1.50; Byte compiler confuses two string variables |
Date: |
Sat, 02 Jun 2018 19:54:40 -0400 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) |
Phil Sainty <psainty@orcon.net.nz> writes:
> On 2018-06-03 06:02, Noam Postavsky wrote:
>> I don't think this is a bug, the compiler coalesces equal string
>> literals.
>
> Ouch. Has this always been the case? I've been firmly under the
> impression that the lisp reader creates a new lisp objects whenever
> it reads a string,
Strictly speaking, that is correct. The reader does that. The byte
compiler doesn't preserve the object identity.
(byte-compile (lambda () (let ((str1 "abc")
(str2 "abc"))
(eq str1 str2))))
;=> #[0 "<bytecode>" ["abc"] 4]
> But this is nil regardless:
>
> (eq "abc" "abc")
Oh, looks like the compiler performs the `eq' call at compile time.
(byte-compile (lambda () (eq "abc" "abc")))
;=> #[0 "\300\207" [nil] 1]
> This seems kinda horrible?
What, you don't like optimization? ;)
- bug#31688: 26.1.50; Byte compiler confuses two string variables, Gemini Lasswell, 2018/06/02
- bug#31688: 26.1.50; Byte compiler confuses two string variables, Noam Postavsky, 2018/06/02
- bug#31688: 26.1.50; Byte compiler confuses two string variables, Gemini Lasswell, 2018/06/02
- bug#31688: 26.1.50; Byte compiler confuses two string variables, Drew Adams, 2018/06/02
- bug#31688: 26.1.50; Byte compiler confuses two string variables, Phil Sainty, 2018/06/02
- bug#31688: 26.1.50; Byte compiler confuses two string variables,
Noam Postavsky <=
- bug#31688: 26.1.50; Byte compiler confuses two string variables, Phil Sainty, 2018/06/03
- bug#31688: 26.1.50; Byte compiler confuses two string variables, Andreas Schwab, 2018/06/03
- bug#31688: 26.1.50; Byte compiler confuses two string variables, Phil Sainty, 2018/06/04
- bug#31688: 26.1.50; Byte compiler confuses two string variables, Eli Zaretskii, 2018/06/04
- bug#31688: 26.1.50; Byte compiler confuses two string variables, Andreas Schwab, 2018/06/04
- bug#31688: 26.1.50; Byte compiler confuses two string variables, Eli Zaretskii, 2018/06/08
- bug#31688: 26.1.50; Byte compiler confuses two string variables, Michael Heerdegen, 2018/06/02
- bug#31688: 26.1.50; Byte compiler confuses two string variables, Drew Adams, 2018/06/02