[gcc r14-7612] gccrs: Only check first item of cfg_attr attribute as predicate

[Arthur Cohen]

https://gcc.gnu.org/g:7e96bfe42867757c35069f2c18abc92c41af0e6b

commit r14-7612-g7e96bfe42867757c35069f2c18abc92c41af0e6b
Author: Matthew Jasper <mjjasper1@gmail.com>
Date:   Sun May 21 20:23:27 2023 +0100

    gccrs: Only check first item of cfg_attr attribute as predicate
    
    In #[cfg_attr(A, B, C(D))], only A is a predicate.
    
    gcc/rust/ChangeLog:
    
            * ast/rust-ast.cc (Attribute::check_cfg_predicate):
            Only check first item as a predicate.
    
    gcc/testsuite/ChangeLog:
    
            * rust/compile/cfg-attr.rs: New test.
    
    Signed-off-by: Matthew Jasper <mjjasper1@gmail.com>

Diff:
---
 gcc/rust/ast/rust-ast.cc               | 3 ++-
 gcc/testsuite/rust/compile/cfg-attr.rs | 7 +++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/gcc/rust/ast/rust-ast.cc b/gcc/rust/ast/rust-ast.cc
index 55b21d3e840..d2550b08607 100644
--- a/gcc/rust/ast/rust-ast.cc
+++ b/gcc/rust/ast/rust-ast.cc
@@ -4183,7 +4183,8 @@ Attribute::check_cfg_predicate (const Session &session) const
   if (!is_parsed_to_meta_item ())
     return false;
 
-  return attr_input->check_cfg_predicate (session);
+  auto &meta_item = static_cast<AttrInputMetaItemContainer &> (*attr_input);
+  return meta_item.get_items ().front ()->check_cfg_predicate (session);
 }
 
 std::vector<Attribute>
diff --git a/gcc/testsuite/rust/compile/cfg-attr.rs b/gcc/testsuite/rust/compile/cfg-attr.rs
new file mode 100644
index 00000000000..137ed2c7adb
--- /dev/null
+++ b/gcc/testsuite/rust/compile/cfg-attr.rs
@@ -0,0 +1,7 @@
+// { dg-additional-options "-w -frust-cfg=A" }
+#![cfg_attr(not(B), allow(dead_code))]
+#![cfg_attr(A, allow(while_true))]
+
+#[cfg_attr(not(B), allow(deprecated))]
+#[cfg_attr(A, allow(drop_bounds))]
+fn main() { }