Rollup merge of rust-lang#89523 - Aaron1011:derive-future-compat, r=w…

…esleywiser

Make `proc_macro_derive_resolution_fallback` a future-breakage lint

When `cargo report future-incompatibilities` is stabilized
(see rust-lang#71249), this will cause dependencies that trigger
this lint to be included in the report.

compiler/rustc_lint_defs/src/builtin.rs

@@ -1960,6 +1960,7 @@ declare_lint! {
     "detects proc macro derives using inaccessible names from parent modules",
     @future_incompatible = FutureIncompatibleInfo {
         reference: "issue #83583 <https://github.com/rust-lang/rust/issues/83583>",
+        reason: FutureIncompatibilityReason::FutureReleaseErrorReportNow,
     };
 }
 

src/test/ui/proc-macro/generate-mod.stderr

@@ -82,3 +82,75 @@ LL |     #[derive(generate_mod::CheckDerive)]
 error: aborting due to 4 previous errors; 4 warnings emitted
 
 For more information about this error, try `rustc --explain E0412`.
+Future incompatibility report: Future breakage diagnostic:
+warning: cannot find type `FromOutside` in this scope
+  --> $DIR/generate-mod.rs:16:10
+   |
+LL | #[derive(generate_mod::CheckDerive)]
+   |          ^^^^^^^^^^^^^^^^^^^^^^^^^ names from parent modules are not accessible without an explicit import
+   |
+   = note: `#[warn(proc_macro_derive_resolution_fallback)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #83583 <https://github.com/rust-lang/rust/issues/83583>
+   = note: this warning originates in the derive macro `generate_mod::CheckDerive` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+Future breakage diagnostic:
+warning: cannot find type `OuterDerive` in this scope
+  --> $DIR/generate-mod.rs:16:10
+   |
+LL | #[derive(generate_mod::CheckDerive)]
+   |          ^^^^^^^^^^^^^^^^^^^^^^^^^ names from parent modules are not accessible without an explicit import
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #83583 <https://github.com/rust-lang/rust/issues/83583>
+   = note: this warning originates in the derive macro `generate_mod::CheckDerive` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+Future breakage diagnostic:
+warning: cannot find type `FromOutside` in this scope
+  --> $DIR/generate-mod.rs:23:14
+   |
+LL |     #[derive(generate_mod::CheckDerive)]
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^ names from parent modules are not accessible without an explicit import
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #83583 <https://github.com/rust-lang/rust/issues/83583>
+   = note: this warning originates in the derive macro `generate_mod::CheckDerive` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+Future breakage diagnostic:
+warning: cannot find type `OuterDerive` in this scope
+  --> $DIR/generate-mod.rs:23:14
+   |
+LL |     #[derive(generate_mod::CheckDerive)]
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^ names from parent modules are not accessible without an explicit import
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #83583 <https://github.com/rust-lang/rust/issues/83583>
+   = note: this warning originates in the derive macro `generate_mod::CheckDerive` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+Future breakage diagnostic:
+warning: cannot find type `FromOutside` in this scope
+  --> $DIR/generate-mod.rs:30:10
+   |
+LL | #[derive(generate_mod::CheckDeriveLint)] // OK, lint is suppressed
+   |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ names from parent modules are not accessible without an explicit import
+   |
+note: the lint level is defined here
+  --> $DIR/generate-mod.rs:30:10
+   |
+LL | #[derive(generate_mod::CheckDeriveLint)] // OK, lint is suppressed
+   |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #83583 <https://github.com/rust-lang/rust/issues/83583>
+   = note: this warning originates in the derive macro `generate_mod::CheckDeriveLint` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+Future breakage diagnostic:
+warning: cannot find type `OuterDeriveLint` in this scope
+  --> $DIR/generate-mod.rs:30:10
+   |
+LL | #[derive(generate_mod::CheckDeriveLint)] // OK, lint is suppressed
+   |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ names from parent modules are not accessible without an explicit import
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #83583 <https://github.com/rust-lang/rust/issues/83583>
+   = note: this warning originates in the derive macro `generate_mod::CheckDeriveLint` (in Nightly builds, run with -Z macro-backtrace for more info)
+