gccrs: rustc_attrs: Allow rustc_inherit_overflow_checks as a builtin..

..attribute. We cannot yet handle this attribute, but we should not reject it either

gcc/rust/ChangeLog:

	* util/rust-attributes.cc: Add `rustc_inherit_overflow_checks` to list
	of builtin attributes.

gcc/testsuite/ChangeLog:

	* rust/compile/rustc_attr1.rs: New test.

gcc/rust/util/rust-attributes.cc

@@ -26,21 +26,23 @@ namespace Rust {
 namespace Analysis {
 
 // https://doc.rust-lang.org/stable/nightly-rustc/src/rustc_feature/builtin_attrs.rs.html#248
-static const BuiltinAttrDefinition __definitions[] = {
-  {"inline", CODE_GENERATION},
-  {"cold", CODE_GENERATION},
-  {"cfg", EXPANSION},
-  {"cfg_attr", EXPANSION},
-  {"deprecated", STATIC_ANALYSIS},
-  {"allow", STATIC_ANALYSIS},
-  {"doc", HIR_LOWERING},
-  {"must_use", STATIC_ANALYSIS},
-  {"lang", HIR_LOWERING},
-  {"link_section", CODE_GENERATION},
-  {"no_mangle", CODE_GENERATION},
-  {"repr", CODE_GENERATION},
-  {"path", EXPANSION},
-};
+static const BuiltinAttrDefinition __definitions[]
+  = {{"inline", CODE_GENERATION},
+     {"cold", CODE_GENERATION},
+     {"cfg", EXPANSION},
+     {"cfg_attr", EXPANSION},
+     {"deprecated", STATIC_ANALYSIS},
+     {"allow", STATIC_ANALYSIS},
+     {"doc", HIR_LOWERING},
+     {"must_use", STATIC_ANALYSIS},
+     {"lang", HIR_LOWERING},
+     {"link_section", CODE_GENERATION},
+     {"no_mangle", CODE_GENERATION},
+     {"repr", CODE_GENERATION},
+     {"path", EXPANSION},
+     // From now on, these are reserved by the compiler and gated through
+     // #![feature(rustc_attrs)]
+     {"rustc_inherit_overflow_checks", CODE_GENERATION}};
 
 BuiltinAttributeMappings *
 BuiltinAttributeMappings::get ()

gcc/testsuite/rust/compile/rustc_attr1.rs

@@ -0,0 +1,13 @@
+// { dg-additional-options "-w" }
+
+#![feature(rustc_attrs)]
+
+pub struct NotI8(i8);
+
+impl NotI8 {
+    #[inline]
+    #[rustc_inherit_overflow_checks]
+    pub fn add(self, other: NotI8) -> NotI8 {
+        NotI8(self.0 + other.0)
+    }
+}