fix ICE on stable related to attrs on macros

Author: jdonszelmann

compiler/rustc_attr_parsing/src/parser.rs

@@ -362,12 +362,8 @@ fn expr_to_lit(
         //   the error because an earlier error will have already
         //   been reported.
         let msg = "attribute value must be a literal";
-        let mut err = psess.dcx().struct_span_err(span, msg);
-        if let ExprKind::Err(_) = expr.kind {
-            err.downgrade_to_delayed_bug();
-        }
-
-        should_emit.emit_err_or_delay(err);
+        let err = psess.dcx().struct_span_err(span, msg);
+        should_emit.maybe_emit_err(err);
         None
     }
 }

tests/ui/lint/unused/concat-in-crate-deprecated-issue-137687.rs

@@ -0,0 +1,6 @@
+//@ check-pass
+#[deprecated = concat !()]
+macro_rules! a {
+    () => {};
+}
+fn main() {}

tests/ui/lint/unused/concat-in-crate-name-issue-137687.rs

@@ -0,0 +1,9 @@
+#![deny(unused)]
+
+#[crate_name = concat !()]
+//~^ ERROR crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]
+macro_rules! a {
+    //~^ ERROR unused macro definition
+    () => {};
+}
+fn main() {}

tests/ui/lint/unused/concat-in-crate-name-issue-137687.stderr

@@ -0,0 +1,23 @@
+error: unused macro definition: `a`
+  --> $DIR/concat-in-crate-name-issue-137687.rs:5:14
+   |
+LL | macro_rules! a {
+   |              ^
+   |
+note: the lint level is defined here
+  --> $DIR/concat-in-crate-name-issue-137687.rs:1:9
+   |
+LL | #![deny(unused)]
+   |         ^^^^^^
+   = note: `#[deny(unused_macros)]` implied by `#[deny(unused)]`
+
+error: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/concat-in-crate-name-issue-137687.rs:3:1
+   |
+LL | #[crate_name = concat !()]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `#[deny(unused_attributes)]` implied by `#[deny(unused)]`
+
+error: aborting due to 2 previous errors
+

tests/ui/resolve/path-attr-in-const-block.rs

@@ -5,5 +5,6 @@ fn main() {
     const {
         #![path = foo!()]
         //~^ ERROR: cannot find macro `foo` in this scope
+        //~| ERROR: attribute value must be a literal
     }
 }

tests/ui/resolve/path-attr-in-const-block.stderr

@@ -4,5 +4,11 @@ error: cannot find macro `foo` in this scope
 LL |         #![path = foo!()]
    |                   ^^^
 
-error: aborting due to 1 previous error
+error: attribute value must be a literal
+  --> $DIR/path-attr-in-const-block.rs:6:19
+   |
+LL |         #![path = foo!()]
+   |                   ^^^^^^
+
+error: aborting due to 2 previous errors