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Fix malfunctioning cursor display on 32-bit Gtk

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This bug on 32-bit platforms was caused by the timespec_hz
definition going haywire because the C expression
FIXNUM_OVERFLOW_P (MOST_POSITIVE_FIXNUM) did not work in #if.
Eventually the numeric problem showed up as a malfunctioning
cursor (Bug#32992).  Fix the problem with MOST_POSITIVE_FIXNUM.
By the way, make_fixnum should check for integer overflow when
debugging; this would have made it easier to track this bug down.
But one fix at a time.
* src/lisp.h (INTTYPEBITS): Now a macro, so usable in #if.
(MOST_POSITIVE_FIXNUM): Mention it’s used in #if.
This commit is contained in:
Paul Eggert 2018-10-09 09:47:28 -07:00
parent bd013a448b
commit 1f88943924
1 changed files with 6 additions and 4 deletions
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src/lisp.h
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@ -236,13 +236,15 @@ enum Lisp_Bits
/* Number of bits in a Lisp_Object value, not counting the tag. */
VALBITS = EMACS_INT_WIDTH - GCTYPEBITS,
/* Number of bits in a Lisp fixnum tag. */
INTTYPEBITS = GCTYPEBITS - 1,
/* Number of bits in a Lisp fixnum value, not counting the tag. */
FIXNUM_BITS = VALBITS + 1
};
/* Number of bits in a Lisp fixnum tag; can be used in #if. */
DEFINE_GDB_SYMBOL_BEGIN (int, INTTYPEBITS)
#define INTTYPEBITS (GCTYPEBITS - 1)
DEFINE_GDB_SYMBOL_END (INTTYPEBITS)
/* The maximum value that can be stored in a EMACS_INT, assuming all
bits other than the type bits contribute to a nonnegative signed value.
This can be used in #if, e.g., '#if USE_LSB_TAG' below expands to an
@ -1034,7 +1036,7 @@ enum More_Lisp_Bits
that cons. */
/* Largest and smallest representable fixnum values. These are the C
values. They are macros for use in static initializers. */
values. They are macros for use in #if and static initializers. */
#define MOST_POSITIVE_FIXNUM (EMACS_INT_MAX >> INTTYPEBITS)
#define MOST_NEGATIVE_FIXNUM (-1 - MOST_POSITIVE_FIXNUM)