Support `#[patchable_function_entries]`

See [RFC](https://github.com/maurer/rust-rfcs/blob/patchable-function-entry/text/0000-patchable-function-entry.md) (yet to be numbered)

TODO before submission:
* Needs an RFC
* Improve error reporting for malformed attributes

1 files changed, 20 insertions, 0 deletions

diff --git a/tests/codegen/patchable-function-entry.rs b/tests/codegen/patchable-function-entry.rs
index f06739303d2..dc20c0a2c6d 100644
--- a/tests/codegen/patchable-function-entry.rs
+++ b/tests/codegen/patchable-function-entry.rs
@@ -1,8 +1,28 @@
+#![feature(patchable_function_entry)]
 // compile-flags: -Z patchable-function-entry=15,10
 
 #![crate_type = "lib"]
 
+// This should have the default, as set by the compile flags
 #[no_mangle]
 pub fn foo() {}
+
+// The attribute should override the compile flags
+#[no_mangle]
+#[patchable_function_entry(prefix(1), entry(2))]
+pub fn bar() {}
+
+// If we override an attribute to 0 or unset, the attribute should go away
+#[no_mangle]
+#[patchable_function_entry(entry(0))]
+pub fn baz() {}
+
 // CHECK: @foo() unnamed_addr #0
+// CHECK: @bar() unnamed_addr #1
+// CHECK: @baz() unnamed_addr #2
+
 // CHECK: attributes #0 = { {{.*}}"patchable-function-entry"="5"{{.*}}"patchable-function-prefix"="10" {{.*}} }
+// CHECK: attributes #1 = { {{.*}}"patchable-function-entry"="2"{{.*}}"patchable-function-prefix"="1" {{.*}} }
+// CHECK-NOT: attributes #2 = { {{.*}}patchable-function-entry{{.*}} }
+// CHECK-NOT: attributes #2 = { {{.*}}patchable-function-prefix{{.*}} }
+// CHECK: attributes #2 = { {{.*}} }