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Adjust intptr_t advice

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* doc/lispref/internals.texi (C Integer Types): Say to prefer
uintptr_t when pointer arithmetic might overflow intptr_t.
This commit is contained in:
Paul Eggert 2019-12-14 14:22:03 -08:00
parent bb42f6ef10
commit 9ee5af3150
1 changed files with 6 additions and 4 deletions
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doc/lispref/internals.texi
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@ -2825,12 +2825,14 @@ POSIX requires support only for values in the range @minus{}1 ..@:
@code{SSIZE_MAX}.
@item
Prefer @code{intptr_t} for internal representations of pointers, or
Normally, prefer @code{intptr_t} for internal representations of pointers, or
for integers bounded only by the number of objects that can exist at
any given time or by the total number of bytes that can be allocated.
Currently Emacs sometimes uses other types when @code{intptr_t} would
be better; fixing this is lower priority, as the code works as-is on
Emacs's current porting targets.
However, prefer @code{uintptr_t} to represent pointer arithmetic that
could cross page boundaries. For example, on a machine with a 32-bit
address space an array could cross the 0x7fffffff/0x80000000 boundary,
which would cause an integer overflow when adding 1 to
@code{(intptr_t) 0x7fffffff}.
@item
Prefer the Emacs-defined type @code{EMACS_INT} for representing values