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doc/go1.3.html: change uintptr to integer in unsafe.Pointer section

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The key property here is what the bit pattern represents,
not what its type is. Storing 5 into a pointer is the problem.
Storing a uintptr that holds pointer bits back into a pointer
is not as much of a problem, and not what we are claiming
the runtime will detect.

Longer discussion at
https://groups.google.com/d/msg/golang-nuts/dIGISmr9hw0/0jO4ce85Eh0J

LGTM=r
R=r
CC=golang-codereviews
https://golang.org/cl/98370045
This commit is contained in:
Russ Cox 2014-05-22 11:45:03 -04:00
parent 5eb585f211
commit 8d8dab34eb
1 changed files with 4 additions and 4 deletions
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doc/go1.3.html
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@ -136,17 +136,17 @@ contain pointers and other values do not.
This assumption is fundamental to the precise behavior of both stack expansion
and garbage collection.
Programs that use <a href="/pkg/unsafe/">package unsafe</a>
to store <code>uintptrs</code> in pointer values are illegal and will crash if the runtime detects the behavior.
to store integers in pointer-typed values are illegal and will crash if the runtime detects the behavior.
Programs that use <a href="/pkg/unsafe/">package unsafe</a> to store pointers
in <code>uintptr</code> values are also illegal but more difficult to diagnose during execution.
in integer-typed values are also illegal but more difficult to diagnose during execution.
Because the pointers are hidden from the runtime, a stack expansion or garbage collection
may reclaim the memory they point at, creating
<a href="http://en.wikipedia.org/wiki/Dangling_pointer">dangling pointers</a>.
</p>
<p>
<em>Updating</em>: Code that converts a <code>uintptr</code> value stored in memory
to <code>unsafe.Pointer</code> is illegal and must be rewritten.
<em>Updating</em>: Code that uses <code>unsafe.Pointer</code> to convert
an integer-typed value held in memory into a pointer is illegal and must be rewritten.
Such code can be identified by <code>go vet</code>.
</p>