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re PR c++/18150 (Should enable -Wsequence-point for C++)

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2006-02-07  Dirk Mueller  <dmueller@suse.com>

       PR c++/18150
       * doc/invoke.texi (-Wsequence-point): Update documentation
       that -Wsequence-point is implemented for C++ as well.

From-SVN: r110719
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Dirk Mueller 2006-02-07 21:47:55 +00:00 committed by Dirk Mueller
parent f5e2061b45
commit 7127d9c7d1
2 changed files with 20 additions and 17 deletions
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@ -1,3 +1,9 @@
2006-02-07 Dirk Mueller <dmueller@suse.com>
PR c++/18150
* doc/invoke.texi (-Wsequence-point): Update documentation
that -Wsequence-point is implemented for C++ as well.
2006-02-07 Eric Botcazou <ebotcazou@libertysurf.fr>
* config/sol26.h (CPP_SUBTARGET_SPEC): Accept -pthread.

31
gcc/doc/invoke.texi
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@ -2526,14 +2526,14 @@ This warning is enabled by @option{-Wall}.
@item -Wsequence-point
@opindex Wsequence-point
Warn about code that may have undefined semantics because of violations
of sequence point rules in the C standard.
of sequence point rules in the C and C++ standards.
The C standard defines the order in which expressions in a C program are
evaluated in terms of @dfn{sequence points}, which represent a partial
ordering between the execution of parts of the program: those executed
before the sequence point, and those executed after it. These occur
after the evaluation of a full expression (one which is not part of a
larger expression), after the evaluation of the first operand of a
The C and C++ standards defines the order in which expressions in a C/C++
program are evaluated in terms of @dfn{sequence points}, which represent
a partial ordering between the execution of parts of the program: those
executed before the sequence point, and those executed after it. These
occur after the evaluation of a full expression (one which is not part
of a larger expression), after the evaluation of the first operand of a
@code{&&}, @code{||}, @code{? :} or @code{,} (comma) operator, before a
function is called (but after the evaluation of its arguments and the
expression denoting the called function), and in certain other places.
@ -2547,11 +2547,11 @@ ruled that function calls do not overlap.
It is not specified when between sequence points modifications to the
values of objects take effect. Programs whose behavior depends on this
have undefined behavior; the C standard specifies that ``Between the
previous and next sequence point an object shall have its stored value
modified at most once by the evaluation of an expression. Furthermore,
the prior value shall be read only to determine the value to be
stored.''. If a program breaks these rules, the results on any
have undefined behavior; the C and C++ standards specify that ``Between
the previous and next sequence point an object shall have its stored
value modified at most once by the evaluation of an expression.
Furthermore, the prior value shall be read only to determine the value
to be stored.''. If a program breaks these rules, the results on any
particular implementation are entirely unpredictable.
Examples of code with undefined behavior are @code{a = a++;}, @code{a[n]
@ -2560,16 +2560,13 @@ diagnosed by this option, and it may give an occasional false positive
result, but in general it has been found fairly effective at detecting
this sort of problem in programs.
The present implementation of this option only works for C programs. A
future implementation may also work for C++ programs.
The C standard is worded confusingly, therefore there is some debate
The standard is worded confusingly, therefore there is some debate
over the precise meaning of the sequence point rules in subtle cases.
Links to discussions of the problem, including proposed formal
definitions, may be found on the GCC readings page, at
@w{@uref{http://gcc.gnu.org/readings.html}}.
This warning is enabled by @option{-Wall}.
This warning is enabled by @option{-Wall} for C and C++.
@item -Wreturn-type
@opindex Wreturn-type