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PR c++/91338 - Implement P1161R3: Deprecate a[b,c].

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* c-opts.c (c_common_post_options): Enable -Wcomma-subscript by
	default for C++2a, unless -Wno-deprecated.
	* c.opt (Wcomma-subscript): New warning.

	* parser.c (cp_parser_postfix_open_square_expression): Warn about uses
	of a comma operator within a subscripting expression.
	(cp_parser_skip_to_closing_square_bracket_1): New function, made out
	of...
	(cp_parser_skip_to_closing_square_bracket): ...this.

	* doc/invoke.texi: Document -Wcomma-subscript.

	* g++.dg/cpp2a/comma1.C: New test.
	* g++.dg/cpp2a/comma2.C: New test.
	* g++.dg/cpp2a/comma3.C: New test.
	* g++.dg/cpp2a/comma4.C: New test.

From-SVN: r274121
This commit is contained in:
Marek Polacek 2019-08-05 19:01:15 +00:00 committed by Marek Polacek
parent ea55c91543
commit ab574db6b9
12 changed files with 236 additions and 9 deletions
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5
gcc/ChangeLog
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@ -1,3 +1,8 @@
2019-08-05 Marek Polacek <polacek@redhat.com>
PR c++/91338 - Implement P1161R3: Deprecate a[b,c].
* doc/invoke.texi: Document -Wcomma-subscript.
2019-08-05 Richard Sandiford <richard.sandiford@arm.com>
* tree-core.h (tree_function_decl): Make function_code an

7
gcc/c-family/ChangeLog
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@ -1,3 +1,10 @@
2019-08-05 Marek Polacek <polacek@redhat.com>
PR c++/91338 - Implement P1161R3: Deprecate a[b,c].
* c-opts.c (c_common_post_options): Enable -Wcomma-subscript by
default for C++2a, unless -Wno-deprecated.
* c.opt (Wcomma-subscript): New warning.
2019-07-20 Jakub Jelinek <jakub@redhat.com>
* c-pragma.h (enum pragma_kind): Add PRAGMA_OMP_LOOP.

4
gcc/c-family/c-opts.c
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@ -916,6 +916,10 @@ c_common_post_options (const char **pfilename)
if (!global_options_set.x_warn_register)
warn_register = cxx_dialect >= cxx17;
/* -Wcomma-subscript is enabled by default in C++20. */
if (!global_options_set.x_warn_comma_subscript)
warn_comma_subscript = (cxx_dialect >= cxx2a && warn_deprecated);
/* Declone C++ 'structors if -Os. */
if (flag_declone_ctor_dtor == -1)
flag_declone_ctor_dtor = optimize_size;

4
gcc/c-family/c.opt
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@ -428,6 +428,10 @@ Wclobbered
C ObjC C++ ObjC++ Var(warn_clobbered) Warning EnabledBy(Wextra)
Warn about variables that might be changed by \"longjmp\" or \"vfork\".
Wcomma-subscript
C++ ObjC++ Var(warn_comma_subscript) Warning
Warn about uses of a comma operator within a subscripting expression.
Wcomment
C ObjC C++ ObjC++ CPP(warn_comments) CppReason(CPP_W_COMMENTS) Var(cpp_warn_comment) Init(0) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
Warn about possibly nested block comments, and C++ comments spanning more than one physical line.

9
gcc/cp/ChangeLog
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@ -1,3 +1,12 @@
2019-08-05 Marek Polacek <polacek@redhat.com>
PR c++/91338 - Implement P1161R3: Deprecate a[b,c].
* parser.c (cp_parser_postfix_open_square_expression): Warn about uses
of a comma operator within a subscripting expression.
(cp_parser_skip_to_closing_square_bracket_1): New function, made out
of...
(cp_parser_skip_to_closing_square_bracket): ...this.
2019-08-05 Jason Merrill <jason@redhat.com>
* semantics.c (force_paren_expr): Preserve location.

80
gcc/cp/parser.c
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@ -2669,6 +2669,8 @@ static bool cp_parser_init_statement_p
(cp_parser *);
static bool cp_parser_skip_to_closing_square_bracket
(cp_parser *);
static int cp_parser_skip_to_closing_square_bracket_1
(cp_parser *, enum cpp_ttype);
/* Concept-related syntactic transformations */
@ -7522,7 +7524,33 @@ cp_parser_postfix_open_square_expression (cp_parser *parser,
index = cp_parser_braced_list (parser, &expr_nonconst_p);
}
else
index = cp_parser_expression (parser);
{
/* [depr.comma.subscript]: A comma expression appearing as
the expr-or-braced-init-list of a subscripting expression
is deprecated. A parenthesized comma expression is not
deprecated. */
if (warn_comma_subscript)
{
/* Save tokens so that we can put them back. */
cp_lexer_save_tokens (parser->lexer);
/* Look for ',' that is not nested in () or {}. */
if (cp_parser_skip_to_closing_square_bracket_1 (parser,
CPP_COMMA) == -1)
{
auto_diagnostic_group d;
warning_at (cp_lexer_peek_token (parser->lexer)->location,
OPT_Wcomma_subscript,
"top-level comma expression in array subscript "
"is deprecated");
}
/* Roll back the tokens we skipped. */
cp_lexer_rollback_tokens (parser->lexer);
}
index = cp_parser_expression (parser);
}
}
parser->greater_than_is_operator_p = saved_greater_than_is_operator_p;
@ -22857,16 +22885,25 @@ cp_parser_braced_list (cp_parser* parser, bool* non_constant_p)
}
/* Consume tokens up to, and including, the next non-nested closing `]'.
Returns true iff we found a closing `]'. */
Returns 1 iff we found a closing `]'. Returns -1 if OR_TTYPE is not
CPP_EOF and we found an unnested token of that type. */
static bool
cp_parser_skip_to_closing_square_bracket (cp_parser *parser)
static int
cp_parser_skip_to_closing_square_bracket_1 (cp_parser *parser,
enum cpp_ttype or_ttype)
{
unsigned square_depth = 0;
unsigned paren_depth = 0;
unsigned brace_depth = 0;
while (true)
{
cp_token * token = cp_lexer_peek_token (parser->lexer);
cp_token *token = cp_lexer_peek_token (parser->lexer);
/* Have we found what we're looking for before the closing square? */
if (token->type == or_ttype && or_ttype != CPP_EOF
&& brace_depth == 0 && paren_depth == 0 && square_depth == 0)
return -1;
switch (token->type)
{
@ -22876,20 +22913,38 @@ cp_parser_skip_to_closing_square_bracket (cp_parser *parser)
/* FALLTHRU */
case CPP_EOF:
/* If we've run out of tokens, then there is no closing `]'. */
return false;
return 0;
case CPP_OPEN_SQUARE:
++square_depth;
break;
case CPP_CLOSE_SQUARE:
if (!square_depth--)
if (square_depth-- == 0)
{
cp_lexer_consume_token (parser->lexer);
return true;
return 1;
}
break;
case CPP_OPEN_BRACE:
++brace_depth;
break;
case CPP_CLOSE_BRACE:
if (brace_depth-- == 0)
return 0;
break;
case CPP_OPEN_PAREN:
++paren_depth;
break;
case CPP_CLOSE_PAREN:
if (paren_depth-- == 0)
return 0;
break;
default:
break;
}
@ -22899,6 +22954,15 @@ cp_parser_skip_to_closing_square_bracket (cp_parser *parser)
}
}
/* Consume tokens up to, and including, the next non-nested closing `]'.
Returns true iff we found a closing `]'. */
static bool
cp_parser_skip_to_closing_square_bracket (cp_parser *parser)
{
return cp_parser_skip_to_closing_square_bracket_1 (parser, CPP_EOF) == 1;
}
/* Return true if we are looking at an array-designator, false otherwise. */
static bool

21
gcc/doc/invoke.texi
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@ -230,7 +230,8 @@ in the following sections.
-fvisibility-inlines-hidden @gol
-fvisibility-ms-compat @gol
-fext-numeric-literals @gol
-Wabi=@var{n} -Wabi-tag -Wconversion-null -Wctor-dtor-privacy @gol
-Wabi=@var{n} -Wabi-tag -Wcomma-subscript -Wconversion-null @gol
-Wctor-dtor-privacy @gol
-Wdelete-non-virtual-dtor -Wdeprecated-copy -Wdeprecated-copy-dtor @gol
-Wliteral-suffix @gol
-Wmultiple-inheritance -Wno-init-list-lifetime @gol
@ -3037,6 +3038,24 @@ Warn when a type with an ABI tag is used in a context that does not
have that ABI tag. See @ref{C++ Attributes} for more information
about ABI tags.
@item -Wcomma-subscript @r{(C++ and Objective-C++ only)}
@opindex Wcomma-subscript
@opindex Wno-comma-subscript
Warn about uses of a comma expression within a subscripting expression.
This usage was deprecated in C++2a. However, a comma expression wrapped
in @code{( )} is not deprecated. Example:
@smallexample
@group
void f(int *a, int b, int c) @{
a[b,c]; // deprecated
a[(b,c)]; // OK
@}
@end group
@end smallexample
Enabled by default with @option{-std=c++2a}.
@item -Wctor-dtor-privacy @r{(C++ and Objective-C++ only)}
@opindex Wctor-dtor-privacy
@opindex Wno-ctor-dtor-privacy

8
gcc/testsuite/ChangeLog
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@ -1,3 +1,11 @@
2019-08-05 Marek Polacek <polacek@redhat.com>
PR c++/91338 - Implement P1161R3: Deprecate a[b,c].
* g++.dg/cpp2a/comma1.C: New test.
* g++.dg/cpp2a/comma2.C: New test.
* g++.dg/cpp2a/comma3.C: New test.
* g++.dg/cpp2a/comma4.C: New test.
2019-08-05 Richard Sandiford <richard.sandiford@arm.com>
* gcc.target/aarch64/sve/mask_load_1.c: New test.

26
gcc/testsuite/g++.dg/cpp2a/comma1.C Normal file
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@ -0,0 +1,26 @@
// PR c++/91338 - P1161R3: Deprecate a[b,c].
// { dg-do compile { target c++11 } }
struct S {
int operator,(int) { return 42; }
};
void
fn (int *a, int b, int c)
{
a[b,c]; // { dg-warning "top-level comma expression in array subscript is deprecated" "" { target c++2a } }
a[(b,c)];
a[(void) b, c]; // { dg-warning "top-level comma expression in array subscript is deprecated" "" { target c++2a } }
a[((void) b, c)];
a[(void) b, (void) c, (void) b, b]; // { dg-warning "top-level comma expression in array subscript is deprecated" "" { target c++2a } }
a[((void) b, (void) c, (void) b, b)];
a[S(), 10]; // { dg-warning "top-level comma expression in array subscript is deprecated" "" { target c++2a } }
a[(S(), 10)];
a[int{(1,2)}];
a[int{(1,2)}, int{}]; // { dg-warning "top-level comma expression in array subscript is deprecated" "" { target c++2a } }
a[(int{(1,2)}, int{})];
}

27
gcc/testsuite/g++.dg/cpp2a/comma2.C Normal file
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@ -0,0 +1,27 @@
// PR c++/91338 - P1161R3: Deprecate a[b,c].
// { dg-do compile { target c++2a } }
// { dg-options "-Wno-comma-subscript" }
struct S {
int operator,(int) { return 42; }
};
void
fn (int *a, int b, int c)
{
a[b,c]; // { dg-bogus "top-level comma expression in array subscript is deprecated" }
a[(b,c)];
a[(void) b, c]; // { dg-bogus "top-level comma expression in array subscript is deprecated" }
a[((void) b, c)];
a[(void) b, (void) c, (void) b, b]; // { dg-bogus "top-level comma expression in array subscript is deprecated" }
a[((void) b, (void) c, (void) b, b)];
a[S(), 10]; // { dg-bogus "top-level comma expression in array subscript is deprecated" }
a[(S(), 10)];
a[int{(1,2)}];
a[int{(1,2)}, int{}]; // { dg-bogus "top-level comma expression in array subscript is deprecated" }
a[(int{(1,2)}, int{})];
}

27
gcc/testsuite/g++.dg/cpp2a/comma3.C Normal file
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@ -0,0 +1,27 @@
// PR c++/91338 - P1161R3: Deprecate a[b,c].
// { dg-do compile { target c++11 } }
// { dg-options "-Wcomma-subscript" }
struct S {
int operator,(int) { return 42; }
};
void
fn (int *a, int b, int c)
{
a[b,c]; // { dg-warning "top-level comma expression in array subscript is deprecated" }
a[(b,c)];
a[(void) b, c]; // { dg-warning "top-level comma expression in array subscript is deprecated" }
a[((void) b, c)];
a[(void) b, (void) c, (void) b, b]; // { dg-warning "top-level comma expression in array subscript is deprecated" }
a[((void) b, (void) c, (void) b, b)];
a[S(), 10]; // { dg-warning "top-level comma expression in array subscript is deprecated" }
a[(S(), 10)];
a[int{(1,2)}];
a[int{(1,2)}, int{}]; // { dg-warning "top-level comma expression in array subscript is deprecated" }
a[(int{(1,2)}, int{})];
}

27
gcc/testsuite/g++.dg/cpp2a/comma4.C Normal file
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@ -0,0 +1,27 @@
// PR c++/91338 - P1161R3: Deprecate a[b,c].
// { dg-do compile { target c++2a } }
// { dg-options "-Wno-deprecated" }
struct S {
int operator,(int) { return 42; }
};
void
fn (int *a, int b, int c)
{
a[b,c]; // { dg-bogus "top-level comma expression in array subscript is deprecated" }
a[(b,c)];
a[(void) b, c]; // { dg-bogus "top-level comma expression in array subscript is deprecated" }
a[((void) b, c)];
a[(void) b, (void) c, (void) b, b]; // { dg-bogus "top-level comma expression in array subscript is deprecated" }
a[((void) b, (void) c, (void) b, b)];
a[S(), 10]; // { dg-bogus "top-level comma expression in array subscript is deprecated" }
a[(S(), 10)];
a[int{(1,2)}];
a[int{(1,2)}, int{}]; // { dg-bogus "top-level comma expression in array subscript is deprecated" }
a[(int{(1,2)}, int{})];
}