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From: "lienze at sourceware dot org" <sourceware-bugzilla@sourceware.org>
To: gdb-prs@sourceware.org
Subject: [Bug cli/24124] Command `b *804874e` sets breakpoint at 0xc480a -
 hex value of 804874
Date: Sun, 04 Sep 2022 08:45:13 +0000
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https://sourceware.org/bugzilla/show_bug.cgi?id=3D24124

--- Comment #4 from Enze Li <lienze at sourceware dot org> ---
(In reply to Tom Tromey from comment #3)
> (In reply to Enze Li from comment #2)
>=20
> > "804874e" is parsed as a floating point number because "en" stands for
> > "10^n".  If there is no decimal number after "e", "e" will be ignored. =
 "d"
> > and "f" are not as special as "e", that is why breakpoint address with =
a "d"
> > or "f" are recognized as illegal.  This is my understanding.
>=20
> I think gdb's lexing here is weird, because it disagrees with C:
>=20
> prentzel. gcc --syntax-only q.c
> q.c:1:11: error: exponent has no digits
>     1 | float x =3D 80e;
>       |           ^~~
>=20
> (gdb) print 80e
> $1 =3D 80
> (gdb) ptype 80e
> type =3D double
>=20
> So not treating this as floating point (and rejecting the parse)
> might be fine.
>=20
> > In GDB, do users usually use decimal numbers to define the address of
> > breakpoints?
>=20
> No but nothing prohibits it.
>=20
> > Or, if only hexadecimal numbers are used to set the breakpoint
> > address, how about we restrict the value of the address to start with 0=
x?
>=20
> That's harder than it sounds because the text after the "*" is an
> arbitrary expression, not just an integer.

Hi Tom,

Thanks for your reply.

I have a proposed patch.  FTR, I've posted here[1].=20

[1] https://sourceware.org/pipermail/gdb-patches/2022-September/191680.html

--=20
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