From 96515f421a9efe88b46091e58533c1bfe875e09e Mon Sep 17 00:00:00 2001
From: Chayim Refael Friedman <chayimfr@gmail.com>
Date: Mon, 7 Mar 2022 16:31:03 +0000
Subject: [PATCH] Do not allow `#[rustc_legacy_const_generics]` on methods

It caused an ICE since `item` was `None`.
---
 compiler/rustc_passes/src/check_attr.rs            |  2 +-
 ...nvalid-rustc_legacy_const_generics-arguments.rs |  5 +++++
 ...id-rustc_legacy_const_generics-arguments.stderr | 14 +++++++++++---
 3 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
index d94ad7ba71a..200bb21504e 100644
--- a/compiler/rustc_passes/src/check_attr.rs
+++ b/compiler/rustc_passes/src/check_attr.rs
@@ -1372,7 +1372,7 @@ impl CheckAttrVisitor<'_> {
         target: Target,
         item: Option<ItemLike<'_>>,
     ) -> bool {
-        let is_function = matches!(target, Target::Fn | Target::Method(..));
+        let is_function = matches!(target, Target::Fn);
         if !is_function {
             self.tcx
                 .sess
diff --git a/src/test/ui/invalid/invalid-rustc_legacy_const_generics-arguments.rs b/src/test/ui/invalid/invalid-rustc_legacy_const_generics-arguments.rs
index 3d8478f06db..6eabd9b1015 100644
--- a/src/test/ui/invalid/invalid-rustc_legacy_const_generics-arguments.rs
+++ b/src/test/ui/invalid/invalid-rustc_legacy_const_generics-arguments.rs
@@ -29,6 +29,11 @@ extern {
 #[rustc_legacy_const_generics(0)] //~ ERROR #[rustc_legacy_const_generics] functions must only have
 fn foo8<X>() {}
 
+impl S {
+    #[rustc_legacy_const_generics(0)] //~ ERROR attribute should be applied to a function
+    fn foo9<const X: usize>() {}
+}
+
 #[rustc_legacy_const_generics] //~ ERROR malformed `rustc_legacy_const_generics` attribute
 fn bar1() {}
 
diff --git a/src/test/ui/invalid/invalid-rustc_legacy_const_generics-arguments.stderr b/src/test/ui/invalid/invalid-rustc_legacy_const_generics-arguments.stderr
index 1f55a8e72d2..bfe7bb2e10d 100644
--- a/src/test/ui/invalid/invalid-rustc_legacy_const_generics-arguments.stderr
+++ b/src/test/ui/invalid/invalid-rustc_legacy_const_generics-arguments.stderr
@@ -7,13 +7,13 @@ LL | #[rustc_legacy_const_generics(0usize)]
    = help: instead of using a suffixed literal (`1u8`, `1.0f32`, etc.), use an unsuffixed version (`1`, `1.0`, etc.)
 
 error: malformed `rustc_legacy_const_generics` attribute input
-  --> $DIR/invalid-rustc_legacy_const_generics-arguments.rs:32:1
+  --> $DIR/invalid-rustc_legacy_const_generics-arguments.rs:37:1
    |
 LL | #[rustc_legacy_const_generics]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: must be of the form: `#[rustc_legacy_const_generics(N)]`
 
 error: malformed `rustc_legacy_const_generics` attribute input
-  --> $DIR/invalid-rustc_legacy_const_generics-arguments.rs:35:1
+  --> $DIR/invalid-rustc_legacy_const_generics-arguments.rs:40:1
    |
 LL | #[rustc_legacy_const_generics = 1]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: must be of the form: `#[rustc_legacy_const_generics(N)]`
@@ -66,6 +66,14 @@ LL | #[rustc_legacy_const_generics(0)]
 LL | fn foo8<X>() {}
    |         - non-const generic parameter
 
+error: attribute should be applied to a function
+  --> $DIR/invalid-rustc_legacy_const_generics-arguments.rs:33:5
+   |
+LL |     #[rustc_legacy_const_generics(0)]
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL |     fn foo9<const X: usize>() {}
+   |     ---------------------------- not a function
+
 error: attribute should be applied to a function
   --> $DIR/invalid-rustc_legacy_const_generics-arguments.rs:25:5
    |
@@ -82,6 +90,6 @@ LL |     fn foo7<const X: usize>();
    |
    = help: replace the const parameters with concrete consts
 
-error: aborting due to 12 previous errors
+error: aborting due to 13 previous errors
 
 For more information about this error, try `rustc --explain E0044`.