[v3] attribs: Fix wrong error with -Wno-attribute=A::b [PR103649]
Commit Message
On Thu, Dec 16, 2021 at 08:06:43PM -0500, Jason Merrill wrote:
> On 12/16/21 19:52, Marek Polacek wrote:
> > --- /dev/null
> > +++ b/gcc/testsuite/c-c++-common/Wno-attributes-6.c
> > @@ -0,0 +1,14 @@
> > +/* PR c/103649 */
> > +/* { dg-do compile { target { c || c++11 } } } */
> > +/* { dg-additional-options "-Wno-attributes=foo::bar" } */
> > +/* { dg-additional-options "-Wno-attributes=baz::" } */
> > +/* { dg-additional-options "-Wno-attributes=womp::womp" } */
> > +/* { dg-additional-options "-Wno-attributes=qux::foo" } */
> > +
> > +[[foo::bar(1, 2)]]; /* { dg-warning "attribute ignored" } */
> > +[[baz::bar(1, 2)]]; /* { dg-warning "attribute ignored" } */
> > +[[foo::bar(1, 2)]] void f1();
> > +[[baz::bar(1, 2)]] void f2();
> > +[[qux::foo({t})]] void f3();
> > +[[womp::womp (another::directive (threadprivate (t)))]] void f4();
> > +[[womp::womp (another::directive (threadprivate (t)))]]; /* { dg-warning "attribute ignored" } */
>
> If we're ignoring these attributes, we should ignore them everywhere;
> perhaps using them for an attribute-declaration is meaningful in another
> compiler.
Sounds good. Reminds me of P177, Portable assumptions...
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
-- >8 --
My patch to implement -Wno-attribute=A::b caused a bogus error when
parsing
[[foo::bar(1, 2)]];
when -Wno-attributes=foo::bar was specified on the command line, because
when we create a fake foo::bar attribute and insert it into our attribute
table, it is created with max_length == 0 which doesn't allow any args.
That is wrong -- we know nothing about the attribute, so we shouldn't
require any specific number of arguments. And since unknown attributes
can be rather complex (see for example omp::{directive,sequence}), we
must skip parsing their arguments. To that end, I'm using max_length
with value -2.
Also let's not warn about things like
[[vendor::assume(true)]];
because they may have some meaning (this is reminiscent of C++ Portable
Assumptions).
PR c/103649
gcc/ChangeLog:
* attribs.c (handle_ignored_attributes_option): Create the fake
attribute with max_length == -2.
(attribute_ignored_p): New function.
* attribs.h (attribute_ignored_p): Declare.
* tree-core.h (struct attribute_spec): Document that max_length
can be -2.
gcc/c/ChangeLog:
* c-decl.c (c_warn_unused_attributes): Don't warn for
attribute_ignored_p.
* c-parser.c (c_parser_std_attribute): Skip parsing of the attribute
arguments when max_length == -2.
gcc/cp/ChangeLog:
* parser.c (cp_parser_declaration): Don't warn for attribute_ignored_p.
(cp_parser_std_attribute): Skip parsing of the attribute
arguments when max_length == -2.
gcc/testsuite/ChangeLog:
* c-c++-common/Wno-attributes-6.c: New test.
---
gcc/attribs.c | 20 ++++++++++++++++++-
gcc/attribs.h | 1 +
gcc/c/c-decl.c | 2 +-
gcc/c/c-parser.c | 4 +++-
gcc/cp/parser.c | 6 ++++--
gcc/testsuite/c-c++-common/Wno-attributes-6.c | 16 +++++++++++++++
gcc/tree-core.h | 4 +++-
7 files changed, 47 insertions(+), 6 deletions(-)
create mode 100644 gcc/testsuite/c-c++-common/Wno-attributes-6.c
base-commit: d7ca2a79b82c6500ead6ab983d14c609e2124eee
Comments
On 12/17/21 13:14, Marek Polacek wrote:
> On Thu, Dec 16, 2021 at 08:06:43PM -0500, Jason Merrill wrote:
>> On 12/16/21 19:52, Marek Polacek wrote:
>>> --- /dev/null
>>> +++ b/gcc/testsuite/c-c++-common/Wno-attributes-6.c
>>> @@ -0,0 +1,14 @@
>>> +/* PR c/103649 */
>>> +/* { dg-do compile { target { c || c++11 } } } */
>>> +/* { dg-additional-options "-Wno-attributes=foo::bar" } */
>>> +/* { dg-additional-options "-Wno-attributes=baz::" } */
>>> +/* { dg-additional-options "-Wno-attributes=womp::womp" } */
>>> +/* { dg-additional-options "-Wno-attributes=qux::foo" } */
>>> +
>>> +[[foo::bar(1, 2)]]; /* { dg-warning "attribute ignored" } */
>>> +[[baz::bar(1, 2)]]; /* { dg-warning "attribute ignored" } */
>>> +[[foo::bar(1, 2)]] void f1();
>>> +[[baz::bar(1, 2)]] void f2();
>>> +[[qux::foo({t})]] void f3();
>>> +[[womp::womp (another::directive (threadprivate (t)))]] void f4();
>>> +[[womp::womp (another::directive (threadprivate (t)))]]; /* { dg-warning "attribute ignored" } */
>>
>> If we're ignoring these attributes, we should ignore them everywhere;
>> perhaps using them for an attribute-declaration is meaningful in another
>> compiler.
>
> Sounds good. Reminds me of P177, Portable assumptions...
>
> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
>
> -- >8 --
> My patch to implement -Wno-attribute=A::b caused a bogus error when
> parsing
>
> [[foo::bar(1, 2)]];
>
> when -Wno-attributes=foo::bar was specified on the command line, because
> when we create a fake foo::bar attribute and insert it into our attribute
> table, it is created with max_length == 0 which doesn't allow any args.
> That is wrong -- we know nothing about the attribute, so we shouldn't
> require any specific number of arguments. And since unknown attributes
> can be rather complex (see for example omp::{directive,sequence}), we
> must skip parsing their arguments. To that end, I'm using max_length
> with value -2.
>
> Also let's not warn about things like
>
> [[vendor::assume(true)]];
>
> because they may have some meaning (this is reminiscent of C++ Portable
> Assumptions).
>
> PR c/103649
>
> gcc/ChangeLog:
>
> * attribs.c (handle_ignored_attributes_option): Create the fake
> attribute with max_length == -2.
> (attribute_ignored_p): New function.
> * attribs.h (attribute_ignored_p): Declare.
> * tree-core.h (struct attribute_spec): Document that max_length
> can be -2.
>
> gcc/c/ChangeLog:
>
> * c-decl.c (c_warn_unused_attributes): Don't warn for
> attribute_ignored_p.
> * c-parser.c (c_parser_std_attribute): Skip parsing of the attribute
> arguments when max_length == -2.
>
> gcc/cp/ChangeLog:
>
> * parser.c (cp_parser_declaration): Don't warn for attribute_ignored_p.
> (cp_parser_std_attribute): Skip parsing of the attribute
> arguments when max_length == -2.
>
> gcc/testsuite/ChangeLog:
>
> * c-c++-common/Wno-attributes-6.c: New test.
> ---
> gcc/attribs.c | 20 ++++++++++++++++++-
> gcc/attribs.h | 1 +
> gcc/c/c-decl.c | 2 +-
> gcc/c/c-parser.c | 4 +++-
> gcc/cp/parser.c | 6 ++++--
> gcc/testsuite/c-c++-common/Wno-attributes-6.c | 16 +++++++++++++++
> gcc/tree-core.h | 4 +++-
> 7 files changed, 47 insertions(+), 6 deletions(-)
> create mode 100644 gcc/testsuite/c-c++-common/Wno-attributes-6.c
>
> diff --git a/gcc/attribs.c b/gcc/attribs.c
> index 29703e75fba..82527869093 100644
> --- a/gcc/attribs.c
> +++ b/gcc/attribs.c
> @@ -304,7 +304,7 @@ handle_ignored_attributes_option (vec<char *> *v)
> We can't free it here, so squirrel away the pointers. */
> attribute_spec *table = new attribute_spec[2];
> ignored_attributes_table.safe_push (table);
> - table[0] = { attr, 0, 0, false, false, false, false, nullptr, nullptr };
> + table[0] = { attr, 0, -2, false, false, false, false, nullptr, nullptr };
> table[1] = { nullptr, 0, 0, false, false, false, false, nullptr,
> nullptr };
> register_scoped_attributes (table, IDENTIFIER_POINTER (vendor_id), !attr);
> @@ -569,6 +569,24 @@ attr_namespace_ignored_p (tree ns)
> return r && r->ignored_p;
> }
>
> +/* Return true if the attribute ATTR should not be warned about. */
> +
> +bool
> +attribute_ignored_p (tree attr)
> +{
> + if (!cxx11_attribute_p (attr))
> + return false;
> + if (tree ns = get_attribute_namespace (attr))
> + {
> + if (attr_namespace_ignored_p (ns))
> + return true;
> + const attribute_spec *as = lookup_attribute_spec (TREE_PURPOSE (attr));
> + if (as && as->max_length == -2)
> + return true;
> + }
> + return false;
> +}
> +
> /* Process the attributes listed in ATTRIBUTES and install them in *NODE,
> which is either a DECL (including a TYPE_DECL) or a TYPE. If a DECL,
> it should be modified in place; if a TYPE, a copy should be created
> diff --git a/gcc/attribs.h b/gcc/attribs.h
> index f5899d83c0b..d3449d5bd1d 100644
> --- a/gcc/attribs.h
> +++ b/gcc/attribs.h
> @@ -39,6 +39,7 @@ extern tree get_attribute_name (const_tree);
> extern tree get_attribute_namespace (const_tree);
> extern void apply_tm_attr (tree, tree);
> extern tree make_attribute (const char *, const char *, tree);
> +extern bool attribute_ignored_p (tree);
>
> extern struct scoped_attributes* register_scoped_attributes (const struct attribute_spec *,
> const char *,
> diff --git a/gcc/c/c-decl.c b/gcc/c/c-decl.c
> index 4b5481ce8f4..516e3c26e21 100644
> --- a/gcc/c/c-decl.c
> +++ b/gcc/c/c-decl.c
> @@ -4643,7 +4643,7 @@ c_warn_unused_attributes (tree attrs)
> constraint violation. */
> pedwarn (input_location, OPT_Wattributes, "%qE attribute ignored",
> get_attribute_name (t));
> - else
> + else if (!attribute_ignored_p (t))
> warning (OPT_Wattributes, "%qE attribute ignored",
> get_attribute_name (t));
> }
> diff --git a/gcc/c/c-parser.c b/gcc/c/c-parser.c
> index d7e5f051ac0..c9068bdbb8a 100644
> --- a/gcc/c/c-parser.c
> +++ b/gcc/c/c-parser.c
> @@ -4943,7 +4943,9 @@ c_parser_std_attribute (c_parser *parser, bool for_tm)
> parens.skip_until_found_close (parser);
> return error_mark_node;
> }
> - if (as)
> + /* When MAX_LENGTH is -2, this is a fake attribute created to
> + handle -Wno-attributes, and we must skip parsing the arguments. */
> + if (as && as->max_length != -2)
> {
> bool takes_identifier
> = (ns != NULL_TREE
> diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
> index 44eed7ea638..a843c953da8 100644
> --- a/gcc/cp/parser.c
> +++ b/gcc/cp/parser.c
> @@ -14776,7 +14776,7 @@ cp_parser_declaration (cp_parser* parser, tree prefix_attrs)
> }
> }
>
> - if (std_attrs != NULL_TREE)
> + if (std_attrs != NULL_TREE && !attribute_ignored_p (std_attrs))
> warning_at (make_location (attrs_loc, attrs_loc, parser->lexer),
> OPT_Wattributes, "attribute ignored");
> if (cp_lexer_next_token_is (parser->lexer, CPP_SEMICOLON))
> @@ -28979,7 +28979,9 @@ cp_parser_std_attribute (cp_parser *parser, tree attr_ns)
> /* A GNU attribute that takes an identifier in parameter. */
> attr_flag = id_attr;
>
> - if (as == NULL)
> + /* When MAX_LENGTH is -2, this is a fake attribute created to
> + handle -Wno-attributes, and we must skip parsing the arguments. */
> + if (as == NULL || as->max_length == -2)
Rather than require multiple places to know about the magic -2, could we
have an overload of attribute_ignored_p that takes an attribute_spec*?
OK with that change.
> {
> if ((flag_openmp || flag_openmp_simd) && attr_ns == omp_identifier)
> {
> diff --git a/gcc/testsuite/c-c++-common/Wno-attributes-6.c b/gcc/testsuite/c-c++-common/Wno-attributes-6.c
> new file mode 100644
> index 00000000000..ca3c7bebb99
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/Wno-attributes-6.c
> @@ -0,0 +1,16 @@
> +/* PR c/103649 */
> +/* { dg-do compile { target { c || c++11 } } } */
> +/* { dg-additional-options "-Wno-attributes=foo::bar" } */
> +/* { dg-additional-options "-Wno-attributes=baz::" } */
> +/* { dg-additional-options "-Wno-attributes=womp::womp" } */
> +/* { dg-additional-options "-Wno-attributes=qux::foo" } */
> +/* { dg-additional-options "-Wno-attributes=vendor::assume" } */
> +
> +[[vendor::assume(1 + 1 == 2)]];
> +[[foo::bar(1, 2)]];
> +[[baz::bar(1, 2)]];
> +[[foo::bar(1, 2)]] void f1();
> +[[baz::bar(1, 2)]] void f2();
> +[[qux::foo({t})]] void f3();
> +[[womp::womp (another::directive (threadprivate (t)))]] void f4();
> +[[womp::womp (another::directive (threadprivate (t)))]];
> diff --git a/gcc/tree-core.h b/gcc/tree-core.h
> index 91ae5237d7e..9b37a065d18 100644
> --- a/gcc/tree-core.h
> +++ b/gcc/tree-core.h
> @@ -2077,7 +2077,9 @@ struct attribute_spec {
> /* The minimum length of the list of arguments of the attribute. */
> int min_length;
> /* The maximum length of the list of arguments of the attribute
> - (-1 for no maximum). */
> + (-1 for no maximum). It can also be -2 for fake attributes
> + created for the sake of -Wno-attributes; in that case, we
> + should skip the balanced token sequence when parsing the attribute. */
> int max_length;
> /* Whether this attribute requires a DECL. If it does, it will be passed
> from types of DECLs, function return types and array element types to
>
> base-commit: d7ca2a79b82c6500ead6ab983d14c609e2124eee
@@ -304,7 +304,7 @@ handle_ignored_attributes_option (vec<char *> *v)
We can't free it here, so squirrel away the pointers. */
attribute_spec *table = new attribute_spec[2];
ignored_attributes_table.safe_push (table);
- table[0] = { attr, 0, 0, false, false, false, false, nullptr, nullptr };
+ table[0] = { attr, 0, -2, false, false, false, false, nullptr, nullptr };
table[1] = { nullptr, 0, 0, false, false, false, false, nullptr,
nullptr };
register_scoped_attributes (table, IDENTIFIER_POINTER (vendor_id), !attr);
@@ -569,6 +569,24 @@ attr_namespace_ignored_p (tree ns)
return r && r->ignored_p;
}
+/* Return true if the attribute ATTR should not be warned about. */
+
+bool
+attribute_ignored_p (tree attr)
+{
+ if (!cxx11_attribute_p (attr))
+ return false;
+ if (tree ns = get_attribute_namespace (attr))
+ {
+ if (attr_namespace_ignored_p (ns))
+ return true;
+ const attribute_spec *as = lookup_attribute_spec (TREE_PURPOSE (attr));
+ if (as && as->max_length == -2)
+ return true;
+ }
+ return false;
+}
+
/* Process the attributes listed in ATTRIBUTES and install them in *NODE,
which is either a DECL (including a TYPE_DECL) or a TYPE. If a DECL,
it should be modified in place; if a TYPE, a copy should be created
@@ -39,6 +39,7 @@ extern tree get_attribute_name (const_tree);
extern tree get_attribute_namespace (const_tree);
extern void apply_tm_attr (tree, tree);
extern tree make_attribute (const char *, const char *, tree);
+extern bool attribute_ignored_p (tree);
extern struct scoped_attributes* register_scoped_attributes (const struct attribute_spec *,
const char *,
@@ -4643,7 +4643,7 @@ c_warn_unused_attributes (tree attrs)
constraint violation. */
pedwarn (input_location, OPT_Wattributes, "%qE attribute ignored",
get_attribute_name (t));
- else
+ else if (!attribute_ignored_p (t))
warning (OPT_Wattributes, "%qE attribute ignored",
get_attribute_name (t));
}
@@ -4943,7 +4943,9 @@ c_parser_std_attribute (c_parser *parser, bool for_tm)
parens.skip_until_found_close (parser);
return error_mark_node;
}
- if (as)
+ /* When MAX_LENGTH is -2, this is a fake attribute created to
+ handle -Wno-attributes, and we must skip parsing the arguments. */
+ if (as && as->max_length != -2)
{
bool takes_identifier
= (ns != NULL_TREE
@@ -14776,7 +14776,7 @@ cp_parser_declaration (cp_parser* parser, tree prefix_attrs)
}
}
- if (std_attrs != NULL_TREE)
+ if (std_attrs != NULL_TREE && !attribute_ignored_p (std_attrs))
warning_at (make_location (attrs_loc, attrs_loc, parser->lexer),
OPT_Wattributes, "attribute ignored");
if (cp_lexer_next_token_is (parser->lexer, CPP_SEMICOLON))
@@ -28979,7 +28979,9 @@ cp_parser_std_attribute (cp_parser *parser, tree attr_ns)
/* A GNU attribute that takes an identifier in parameter. */
attr_flag = id_attr;
- if (as == NULL)
+ /* When MAX_LENGTH is -2, this is a fake attribute created to
+ handle -Wno-attributes, and we must skip parsing the arguments. */
+ if (as == NULL || as->max_length == -2)
{
if ((flag_openmp || flag_openmp_simd) && attr_ns == omp_identifier)
{
new file mode 100644
@@ -0,0 +1,16 @@
+/* PR c/103649 */
+/* { dg-do compile { target { c || c++11 } } } */
+/* { dg-additional-options "-Wno-attributes=foo::bar" } */
+/* { dg-additional-options "-Wno-attributes=baz::" } */
+/* { dg-additional-options "-Wno-attributes=womp::womp" } */
+/* { dg-additional-options "-Wno-attributes=qux::foo" } */
+/* { dg-additional-options "-Wno-attributes=vendor::assume" } */
+
+[[vendor::assume(1 + 1 == 2)]];
+[[foo::bar(1, 2)]];
+[[baz::bar(1, 2)]];
+[[foo::bar(1, 2)]] void f1();
+[[baz::bar(1, 2)]] void f2();
+[[qux::foo({t})]] void f3();
+[[womp::womp (another::directive (threadprivate (t)))]] void f4();
+[[womp::womp (another::directive (threadprivate (t)))]];
@@ -2077,7 +2077,9 @@ struct attribute_spec {
/* The minimum length of the list of arguments of the attribute. */
int min_length;
/* The maximum length of the list of arguments of the attribute
- (-1 for no maximum). */
+ (-1 for no maximum). It can also be -2 for fake attributes
+ created for the sake of -Wno-attributes; in that case, we
+ should skip the balanced token sequence when parsing the attribute. */
int max_length;
/* Whether this attribute requires a DECL. If it does, it will be passed
from types of DECLs, function return types and array element types to