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Commit 8ff24a79 by Mark Mitchell Committed by Mark Mitchell
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extend.texi: Deprecate C++ min/max operators. 

	* doc/extend.texi: Deprecate C++ min/max operators.

	* parser.c (cp_parser_warn_min_max): New function.
	(cp_parser_binary_expression): Use it.
	(cp_parser_assignment_operator_opt): Likewise.
	(cp_parser_operator): Likewise.

	* g++.dg/opt/max1.C: Run with -Wno-deprecated.
	* g++.dg/opt/pr7503-2.C: Likewise.
	* g++.dg/opt/pr7503-3.C: Likewise.
	* g++.dg/opt/pr7503-4.C: Likewise.
	* g++.dg/opt/pr7503-5.C: Likewise.
	* g++.dg/warn/minmax.C: New test.

From-SVN: r96899
parent 0dc8f327
Showing with 64 additions and 51 deletions
gcc/ChangeLog
2005-03-22 Mark Mitchell <mark@codesourcery.com>
* doc/extend.texi: Deprecate C++ min/max operators.
2005-03-22 Zdenek Dvorak <dvorakz@suse.cz>
* tree-ssa-loop-ivopts.c (determine_iv_cost): Do not try to preserve
......
gcc/cp/ChangeLog
2005-03-22 Mark Mitchell <mark@codesourcery.com>
* parser.c (cp_parser_warn_min_max): New function.
(cp_parser_binary_expression): Use it.
(cp_parser_assignment_operator_opt): Likewise.
(cp_parser_operator): Likewise.
2005-03-22 Volker Reichelt <reichelt@igpm.rwth-aachen.de>
PR c++/19980
......
gcc/cp/parser.c
......@@ -1787,6 +1787,16 @@ cp_parser_is_keyword (cp_token* token, enum rid keyword)
return token->keyword == keyword;
}
/* A minimum or maximum operator has been seen. As these are
deprecated, issue a warning. */
static inline void
cp_parser_warn_min_max (void)
{
if (warn_deprecated && !in_system_header)
warning ("minimum/maximum operators are deprecated");
}
/* If not parsing tentatively, issue a diagnostic of the form
FILE:LINE: MESSAGE before TOKEN
where TOKEN is the next token in the input stream. MESSAGE
......@@ -5401,6 +5411,9 @@ cp_parser_binary_expression (cp_parser* parser, bool cast_p)
{
/* Get an operator token. */
token = cp_lexer_peek_token (parser->lexer);
if (token->type == CPP_MIN || token->type == CPP_MAX)
cp_parser_warn_min_max ();
new_prec = TOKEN_PRECEDENCE (token);
/* Popping an entry off the stack means we completed a subexpression:
......@@ -5656,10 +5669,12 @@ cp_parser_assignment_operator_opt (cp_parser* parser)
case CPP_MIN_EQ:
op = MIN_EXPR;
cp_parser_warn_min_max ();
break;
case CPP_MAX_EQ:
op = MAX_EXPR;
cp_parser_warn_min_max ();
break;
default:
......@@ -8039,18 +8054,22 @@ cp_parser_operator (cp_parser* parser)
/* Extensions. */
case CPP_MIN:
id = ansi_opname (MIN_EXPR);
cp_parser_warn_min_max ();
break;
case CPP_MAX:
id = ansi_opname (MAX_EXPR);
cp_parser_warn_min_max ();
break;
case CPP_MIN_EQ:
id = ansi_assopname (MIN_EXPR);
cp_parser_warn_min_max ();
break;
case CPP_MAX_EQ:
id = ansi_assopname (MAX_EXPR);
cp_parser_warn_min_max ();
break;
default:
......
gcc/doc/extend.texi
......@@ -9130,7 +9130,6 @@ test specifically for GNU C++ (@pxref{Common Predefined Macros,,
Predefined Macros,cpp,The GNU C Preprocessor}).
@menu
* Min and Max:: C++ Minimum and maximum operators.
* Volatiles:: What constitutes an access to a volatile object.
* Restricted Pointers:: C99 restricted pointers and references.
* Vague Linkage:: Where G++ puts inlines, vtables and such.
......@@ -9147,51 +9146,6 @@ Predefined Macros,cpp,The GNU C Preprocessor}).
* Backwards Compatibility:: Compatibilities with earlier definitions of C++.
@end menu
@node Min and Max
@section Minimum and Maximum Operators in C++
It is very convenient to have operators which return the ``minimum'' or the
``maximum'' of two arguments. In GNU C++ (but not in GNU C),
@table @code
@item @var{a} <? @var{b}
@findex <?
@cindex minimum operator
is the @dfn{minimum}, returning the smaller of the numeric values
@var{a} and @var{b};
@item @var{a} >? @var{b}
@findex >?
@cindex maximum operator
is the @dfn{maximum}, returning the larger of the numeric values @var{a}
and @var{b}.
@end table
These operations are not primitive in ordinary C++, since you can
use a macro to return the minimum of two things in C++, as in the
following example.
@smallexample
#define MIN(X,Y) ((X) < (Y) ? : (X) : (Y))
@end smallexample
@noindent
You might then use @w{@samp{int min = MIN (i, j);}} to set @var{min} to
the minimum value of variables @var{i} and @var{j}.
However, side effects in @code{X} or @code{Y} may cause unintended
behavior. For example, @code{MIN (i++, j++)} will fail, incrementing
the smaller counter twice. The GNU C @code{typeof} extension allows you
to write safe macros that avoid this kind of problem (@pxref{Typeof}).
However, writing @code{MIN} and @code{MAX} as macros also forces you to
use function-call notation for a fundamental arithmetic operation.
Using GNU C++ extensions, you can write @w{@samp{int min = i <? j;}}
instead.
Since @code{<?} and @code{>?} are built into the compiler, they properly
handle expressions with side-effects; @w{@samp{int min = i++ <? j++;}}
works correctly.
@node Volatiles
@section When is a Volatile Object Accessed?
@cindex accessing volatiles
......@@ -9838,6 +9792,11 @@ by one returning a different pointer type. This extension to the
covariant return type rules is now deprecated and will be removed from a
future version.
The G++ minimum and maximum operators (@samp{<?} and @samp{>?}) and
their compound forms (@samp{<?=}) and @samp{>?=}) have been deprecated
and will be removed in a future version. Code using these operators
should be modified to use @code{std::min} and @code{std::max} instead.
The named return value extension has been deprecated, and is now
removed from G++.
......
gcc/testsuite/ChangeLog
2005-03-22 Mark Mitchell <mark@codesourcery.com>
* g++.dg/opt/max1.C: Run with -Wno-deprecated.
* g++.dg/opt/pr7503-2.C: Likewise.
* g++.dg/opt/pr7503-3.C: Likewise.
* g++.dg/opt/pr7503-4.C: Likewise.
* g++.dg/opt/pr7503-5.C: Likewise.
* g++.dg/warn/minmax.C: New test.
2005-03-22 Francois-Xavier Coudert <coudert@clipper.ens.fr>
* g77_intrinsics_funcs.f: New test.
......
gcc/testsuite/g++.dg/opt/max1.C
/* PR middle-end/19068 */
/* Test case by Andrew Pinski <pinskia@physics.uc.edu> */
/* { dg-do run } */
/* { dg-options "-O2" } */
/* { dg-options "-O2 -Wno-deprecated" } */
extern "C" void abort (void);
......
gcc/testsuite/g++.dg/opt/pr7503-2.C
// PR c++/7503
// { dg-do run }
// { dg-options "-O2" }
// { dg-options "-O2 -Wno-deprecated" }
extern "C" void abort();
......
gcc/testsuite/g++.dg/opt/pr7503-3.C
// PR c++/7503
// { dg-do compile }
// { dg-options "-O2" }
// { dg-options "-O2 -Wno-deprecated" }
extern int A, B;
......
gcc/testsuite/g++.dg/opt/pr7503-4.C
// PR c++/7503
// { dg-do run }
// { dg-options "-O2" }
// { dg-options "-O2 -Wno-deprecated" }
extern "C" void abort();
......
gcc/testsuite/g++.dg/opt/pr7503-5.C
// PR c++/7503
// { dg-do run }
// { dg-options "-O2" }
// { dg-options "-O2 -Wno-deprecated" }
extern "C" void abort();
......
gcc/testsuite/g++.dg/warn/minmax.C 0 → 100644
int i, j, k;
void f() {
i = j <? k; // { dg-warning "deprecated" }
i = j >? k; // { dg-warning "deprecated" }
i <?= j; // { dg-warning "deprecated" }
i >?= j; // { dg-warning "deprecated" }
}
struct S {
void operator<?(int); // { dg-warning "deprecated" }
void operator>?(int); // { dg-warning "deprecated" }
void operator<?=(int); // { dg-warning "deprecated" }
void operator>?=(int); // { dg-warning "deprecated" }
};
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