public inbox for gdb-prs@sourceware.org
help / color / mirror / Atom feed
* [Bug rust/29859] New: Printing rust expressions with simple arithmetic gets wrong result
@ 2022-12-06 12:33 bpeeluk at yahoo dot co.uk
2022-12-06 14:14 ` [Bug rust/29859] " tromey at sourceware dot org
` (7 more replies)
0 siblings, 8 replies; 9+ messages in thread
From: bpeeluk at yahoo dot co.uk @ 2022-12-06 12:33 UTC (permalink / raw)
To: gdb-prs
https://sourceware.org/bugzilla/show_bug.cgi?id=29859
Bug ID: 29859
Summary: Printing rust expressions with simple arithmetic gets
wrong result
Product: gdb
Version: HEAD
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: rust
Assignee: unassigned at sourceware dot org
Reporter: bpeeluk at yahoo dot co.uk
Target Milestone: ---
The rust parser doesn’t seem to handle expressions with multiple binary
operators but no parentheses correctly:
(gdb) p 3 - 2 - 1
$1 = 2
(gdb) p 5 * 4 / 3
$2 = 5
It seems to be calculating the answer as if the operators were right-to-left:
(gdb) p 3 - (2 - 1)
$3 = 2
(gdb) p 5 * (4 / 3)
$4 = 5
But it should be doing left-to-right:
(gdb) p (3 - 2) - 1
$5 = 0
(gdb) p (5 * 4) / 3
$6 = 6
I tested this with the current git master which is c8ea5e409b02cf7fa8.
Another way to test this could be to add the following lines to the bottom of
gdb/testsuite/gdb.rust/expr.exp:
gdb_test "print 3 - 2 - 1" " = 0"
gdb_test "print 5 * 4 / 3" " = 6"
and then run:
( cd gdb/testsuite && runtest gdb.rust/expr.exp )
--
You are receiving this mail because:
You are on the CC list for the bug.
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug rust/29859] Printing rust expressions with simple arithmetic gets wrong result
2022-12-06 12:33 [Bug rust/29859] New: Printing rust expressions with simple arithmetic gets wrong result bpeeluk at yahoo dot co.uk
@ 2022-12-06 14:14 ` tromey at sourceware dot org
2022-12-06 14:43 ` cvs-commit at gcc dot gnu.org
` (6 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: tromey at sourceware dot org @ 2022-12-06 14:14 UTC (permalink / raw)
To: gdb-prs
https://sourceware.org/bugzilla/show_bug.cgi?id=29859
Tom Tromey <tromey at sourceware dot org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed| |2022-12-06
Ever confirmed|0 |1
Assignee|unassigned at sourceware dot org |tromey at sourceware dot org
CC| |tromey at sourceware dot org
Status|UNCONFIRMED |NEW
--- Comment #1 from Tom Tromey <tromey at sourceware dot org> ---
Ugh. Looks like an operator precedence error in the parser rewrite :(
--
You are receiving this mail because:
You are on the CC list for the bug.
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug rust/29859] Printing rust expressions with simple arithmetic gets wrong result
2022-12-06 12:33 [Bug rust/29859] New: Printing rust expressions with simple arithmetic gets wrong result bpeeluk at yahoo dot co.uk
2022-12-06 14:14 ` [Bug rust/29859] " tromey at sourceware dot org
@ 2022-12-06 14:43 ` cvs-commit at gcc dot gnu.org
2022-12-06 14:43 ` tromey at sourceware dot org
` (5 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2022-12-06 14:43 UTC (permalink / raw)
To: gdb-prs
https://sourceware.org/bugzilla/show_bug.cgi?id=29859
--- Comment #2 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Tom Tromey <tromey@sourceware.org>:
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=e03698c1227bc18835cc2e4a9146a8369635e119
commit e03698c1227bc18835cc2e4a9146a8369635e119
Author: Tom Tromey <tromey@adacore.com>
Date: Tue Dec 6 07:41:52 2022 -0700
Fix operator precedence bug in Rust parser
PR rust/29859 points out an operator precedence bug in the Rust
parser. This patch fixes it and adds a regression test.
--
You are receiving this mail because:
You are on the CC list for the bug.
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug rust/29859] Printing rust expressions with simple arithmetic gets wrong result
2022-12-06 12:33 [Bug rust/29859] New: Printing rust expressions with simple arithmetic gets wrong result bpeeluk at yahoo dot co.uk
2022-12-06 14:14 ` [Bug rust/29859] " tromey at sourceware dot org
2022-12-06 14:43 ` cvs-commit at gcc dot gnu.org
@ 2022-12-06 14:43 ` tromey at sourceware dot org
2022-12-06 15:37 ` bpeeluk at yahoo dot co.uk
` (4 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: tromey at sourceware dot org @ 2022-12-06 14:43 UTC (permalink / raw)
To: gdb-prs
https://sourceware.org/bugzilla/show_bug.cgi?id=29859
Tom Tromey <tromey at sourceware dot org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |FIXED
Status|NEW |RESOLVED
Target Milestone|--- |13.1
--- Comment #3 from Tom Tromey <tromey at sourceware dot org> ---
Fixed. Sorry about that.
--
You are receiving this mail because:
You are on the CC list for the bug.
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug rust/29859] Printing rust expressions with simple arithmetic gets wrong result
2022-12-06 12:33 [Bug rust/29859] New: Printing rust expressions with simple arithmetic gets wrong result bpeeluk at yahoo dot co.uk
` (2 preceding siblings ...)
2022-12-06 14:43 ` tromey at sourceware dot org
@ 2022-12-06 15:37 ` bpeeluk at yahoo dot co.uk
2022-12-06 22:14 ` tromey at sourceware dot org
` (3 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: bpeeluk at yahoo dot co.uk @ 2022-12-06 15:37 UTC (permalink / raw)
To: gdb-prs
https://sourceware.org/bugzilla/show_bug.cgi?id=29859
--- Comment #4 from Neil Roberts <bpeeluk at yahoo dot co.uk> ---
Thanks for the very quick response.
This is just nitpicking and I guess it doesn’t really matter, but I’d like to
point out that this commit has effectively changed all operators to be
left-to-right associative whereas previously they were all right-to-left
associative. This is clearly an improvement because almost all of the operators
are supposed to be left-to-right. However, the assignment operators really are
supposed to be right-to-left as you can see in the Rust docs:
https://doc.rust-lang.org/reference/expressions.html#expression-precedence
So now we have a regression where previously we had this correct behaviour:
(gdb) p $a = $b = 3
$1 = ()
This was being interpreted as $a = ($b = 3). The value of an assignment
expression is () (unlike in C), so $a becomes ().
After the patch it gives an error:
(gdb) p $a = $b = 3
Left operand of assignment is not an lvalue.
That’s presumably because it’s being interpreted as “($a = $b) = 3” and “$a =
$b” isn’t an lvalue.
--
You are receiving this mail because:
You are on the CC list for the bug.
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug rust/29859] Printing rust expressions with simple arithmetic gets wrong result
2022-12-06 12:33 [Bug rust/29859] New: Printing rust expressions with simple arithmetic gets wrong result bpeeluk at yahoo dot co.uk
` (3 preceding siblings ...)
2022-12-06 15:37 ` bpeeluk at yahoo dot co.uk
@ 2022-12-06 22:14 ` tromey at sourceware dot org
2022-12-12 13:44 ` cvs-commit at gcc dot gnu.org
` (2 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: tromey at sourceware dot org @ 2022-12-06 22:14 UTC (permalink / raw)
To: gdb-prs
https://sourceware.org/bugzilla/show_bug.cgi?id=29859
Tom Tromey <tromey at sourceware dot org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|RESOLVED |REOPENED
Resolution|FIXED |---
--- Comment #5 from Tom Tromey <tromey at sourceware dot org> ---
I'll fix that too, sorry.
--
You are receiving this mail because:
You are on the CC list for the bug.
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug rust/29859] Printing rust expressions with simple arithmetic gets wrong result
2022-12-06 12:33 [Bug rust/29859] New: Printing rust expressions with simple arithmetic gets wrong result bpeeluk at yahoo dot co.uk
` (4 preceding siblings ...)
2022-12-06 22:14 ` tromey at sourceware dot org
@ 2022-12-12 13:44 ` cvs-commit at gcc dot gnu.org
2022-12-12 13:46 ` tromey at sourceware dot org
2022-12-13 13:01 ` bpeeluk at yahoo dot co.uk
7 siblings, 0 replies; 9+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2022-12-12 13:44 UTC (permalink / raw)
To: gdb-prs
https://sourceware.org/bugzilla/show_bug.cgi?id=29859
--- Comment #6 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Tom Tromey <tromey@sourceware.org>:
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=67a8c89601f6e1947484d5de23411634fef92e68
commit 67a8c89601f6e1947484d5de23411634fef92e68
Author: Tom Tromey <tom@tromey.com>
Date: Mon Dec 12 06:36:55 2022 -0700
Another Rust operator precedence bug
My earlier patch to fix PR rust/29859 introduced a new operator
precedence bug in the Rust parser. Assignment operators are
right-associative in Rust. And, while this doesn't often matter, as
Rust assignments always have the value (), still as a matter of
principle we should get this correct.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29859
--
You are receiving this mail because:
You are on the CC list for the bug.
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug rust/29859] Printing rust expressions with simple arithmetic gets wrong result
2022-12-06 12:33 [Bug rust/29859] New: Printing rust expressions with simple arithmetic gets wrong result bpeeluk at yahoo dot co.uk
` (5 preceding siblings ...)
2022-12-12 13:44 ` cvs-commit at gcc dot gnu.org
@ 2022-12-12 13:46 ` tromey at sourceware dot org
2022-12-13 13:01 ` bpeeluk at yahoo dot co.uk
7 siblings, 0 replies; 9+ messages in thread
From: tromey at sourceware dot org @ 2022-12-12 13:46 UTC (permalink / raw)
To: gdb-prs
https://sourceware.org/bugzilla/show_bug.cgi?id=29859
Tom Tromey <tromey at sourceware dot org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |FIXED
Status|REOPENED |RESOLVED
--- Comment #7 from Tom Tromey <tromey at sourceware dot org> ---
Ok, should be fixed again.
--
You are receiving this mail because:
You are on the CC list for the bug.
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug rust/29859] Printing rust expressions with simple arithmetic gets wrong result
2022-12-06 12:33 [Bug rust/29859] New: Printing rust expressions with simple arithmetic gets wrong result bpeeluk at yahoo dot co.uk
` (6 preceding siblings ...)
2022-12-12 13:46 ` tromey at sourceware dot org
@ 2022-12-13 13:01 ` bpeeluk at yahoo dot co.uk
7 siblings, 0 replies; 9+ messages in thread
From: bpeeluk at yahoo dot co.uk @ 2022-12-13 13:01 UTC (permalink / raw)
To: gdb-prs
https://sourceware.org/bugzilla/show_bug.cgi?id=29859
--- Comment #8 from Neil Roberts <bpeeluk at yahoo dot co.uk> ---
Brilliant, thank you!
--
You are receiving this mail because:
You are on the CC list for the bug.
^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2022-12-13 13:01 UTC | newest]
Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-12-06 12:33 [Bug rust/29859] New: Printing rust expressions with simple arithmetic gets wrong result bpeeluk at yahoo dot co.uk
2022-12-06 14:14 ` [Bug rust/29859] " tromey at sourceware dot org
2022-12-06 14:43 ` cvs-commit at gcc dot gnu.org
2022-12-06 14:43 ` tromey at sourceware dot org
2022-12-06 15:37 ` bpeeluk at yahoo dot co.uk
2022-12-06 22:14 ` tromey at sourceware dot org
2022-12-12 13:44 ` cvs-commit at gcc dot gnu.org
2022-12-12 13:46 ` tromey at sourceware dot org
2022-12-13 13:01 ` bpeeluk at yahoo dot co.uk
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).