On Thu, Dec 16, 2021 at 11:53:46PM +0100, Jakub Jelinek wrote:
> On Thu, Dec 16, 2021 at 05:35:55PM -0500, Marek Polacek wrote:
> > 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.
> >
> > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> >
> > PR c/103649
> >
> > gcc/ChangeLog:
> >
> > * attribs.c (handle_ignored_attributes_option): Create the fake
> > attribute with max_length == -1.
> >
> > gcc/testsuite/ChangeLog:
> >
> > * c-c++-common/Wno-attributes-6.c: New test.
>
> I'm afraid this still changes behavior. 0, -1 range attribute arguments
> are parsed normally, while unknown attributes have the balanced token
> sequence skipped.
> E.g. the omp::{directive,sequence} attribute arguments are much more complex
> than what the normal parsing can handle.
> Can you make max -2 instead and special case it in the C and C++ FE
> attribute handling and in a testcase try something that is a balanced token
> sequence but not really valid when parsed as ordinary attributes' arguments?
Ah I see what you mean now. Fixed here, thanks.
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.
PR c/103649
gcc/ChangeLog:
* attribs.c (handle_ignored_attributes_option): Create the fake
attribute with max_length == -2.
* tree-core.h (struct attribute_spec): Document that max_length
can be -2.
gcc/c/ChangeLog:
* c-parser.c (c_parser_std_attribute): Skip parsing of the attribute
arguments when max_length == -2.
gcc/cp/ChangeLog:
* parser.c (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 | 2 +-
gcc/c/c-parser.c | 4 +++-
gcc/cp/parser.c | 4 +++-
gcc/testsuite/c-c++-common/Wno-attributes-6.c | 14 ++++++++++++++
gcc/tree-core.h | 4 +++-
5 files changed, 24 insertions(+), 4 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..6af7f93e61c 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);
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..763d74eaf6c 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -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)
{
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..0b2dd5aa290
--- /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" } */
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: 840a22e0fee9e7369a2eb1c9e3c70dcae24a20e4
--
2.33.1
