[COMMITTED 13/46] gccrs: util/attributes: Check that #[target_feature] is only used on unsafe functions

[arthur . cohen]

From: Jayant Chauhan <0001jay...@gmail.com>

The #[target_feature] attribute allows code generation that may not be
supported by the runtime hardware, making it inherently unsafe. This
patch adds a check to ensure it is only applied to functions declared
as 'unsafe', matching rustc behavior (E0658).

Fixes Rust-GCC#4234

gcc/rust/ChangeLog:

        * util/rust-attributes.cc (AttributeChecker::visit):
        Reject #[target_feature] on non-unsafe functions.

gcc/testsuite/ChangeLog:

        * rust/compile/issue-4234.rs: New test.
        * rust/compile/unsafe11.rs: Mark function as unsafe to
        to satisfy new #[target_feature] restriction.

Signed-off-by: Jayant Chauhan <0001jay...@gmail.com>
---
 gcc/rust/util/rust-attributes.cc         | 7 +++++++
 gcc/testsuite/rust/compile/issue-4234.rs | 3 +++
 gcc/testsuite/rust/compile/unsafe11.rs   | 5 +++--
 3 files changed, 13 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/rust/compile/issue-4234.rs

diff --git a/gcc/rust/util/rust-attributes.cc b/gcc/rust/util/rust-attributes.cc
index bf7f3d9827d..a58336ef9e3 100644
--- a/gcc/rust/util/rust-attributes.cc
+++ b/gcc/rust/util/rust-attributes.cc
@@ -885,6 +885,13 @@ AttributeChecker::visit (AST::Function &fun)
                           "must be of the form: %<#[target_feature(enable = "
                           "\"name\")]%>");
            }
+         else if (!fun.get_qualifiers ().is_unsafe ())
+           {
+             rust_error_at (
+               attribute.get_locus (),
+               "the %<#[target_feature]%> attribute can only be applied "
+               "to %<unsafe%> functions");
+           }
        }
       else if (result.name == "no_mangle")
        {
diff --git a/gcc/testsuite/rust/compile/issue-4234.rs 
b/gcc/testsuite/rust/compile/issue-4234.rs
new file mode 100644
index 00000000000..bb60e35ace6
--- /dev/null
+++ b/gcc/testsuite/rust/compile/issue-4234.rs
@@ -0,0 +1,3 @@
+// { dg-options "-w" }
+#[target_feature(sse)] // { dg-error "attribute can only be applied" }
+fn foo() {}
\ No newline at end of file
diff --git a/gcc/testsuite/rust/compile/unsafe11.rs 
b/gcc/testsuite/rust/compile/unsafe11.rs
index c87902fcd5f..e6657a6d6cb 100644
--- a/gcc/testsuite/rust/compile/unsafe11.rs
+++ b/gcc/testsuite/rust/compile/unsafe11.rs
@@ -1,8 +1,9 @@
 #[target_feature(sse)]
-fn foo() {
+unsafe fn foo() {
     let a: usize = 0;
 }
 
 fn main() {
-    foo() // { dg-error "requires unsafe function or block" }
+    foo(); // { dg-error "requires unsafe function or block" }
+    unsafe { foo(); }
 }
-- 
2.50.1