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Commit cc61dc8

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Rollup merge of #127655 - RalfJung:invalid_type_param_default, r=compiler-errors
turn `invalid_type_param_default` into a `FutureReleaseErrorReportInDeps` `````@rust-lang/types````` I assume the plan is still to disallow this? It has been a future-compat lint for a long time, seems ripe to go for hard error. However, turns out that outright removing it right now would lead to [tons of crater regressions](#127655 (comment)), so for now this PR just makes this future-compat lint show up in cargo's reports, so people are warned when they use a dependency that is affected by this. Fixes #27336 by removing the feature gate (so there's no way to silence the lint even on nightly) CC #36887 
2 parents 176e545 + 9d9b55c commit cc61dc8

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12 files changed

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12 files changed

+115
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‎compiler/rustc_feature/src/removed.rs‎

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@@ -82,6 +82,9 @@ declare_features! (
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/// Allows the use of `#[derive(Anything)]` as sugar for `#[derive_Anything]`.
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(removed, custom_derive, "1.32.0", Some(29644),
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Some("subsumed by `#[proc_macro_derive]`")),
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/// Allows default type parameters to influence type inference.
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(removed, default_type_parameter_fallback, "CURRENT_RUSTC_VERSION", Some(27336),
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Some("never properly implemented; requires significant design work")),
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/// Allows using `#[doc(keyword = "...")]`.
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(removed, doc_keyword, "1.28.0", Some(51315),
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Some("merged into `#![feature(rustdoc_internals)]`")),

‎compiler/rustc_feature/src/unstable.rs‎

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@@ -431,8 +431,6 @@ declare_features! (
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(unstable, custom_test_frameworks, "1.30.0", Some(50297)),
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/// Allows declarative macros 2.0 (`macro`).
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(unstable, decl_macro, "1.17.0", Some(39412)),
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/// Allows default type parameters to influence type inference.
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(unstable, default_type_parameter_fallback, "1.3.0", Some(27336)),
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/// Allows using `#[deprecated_safe]` to deprecate the safeness of a function or trait
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(unstable, deprecated_safe, "1.61.0", Some(94978)),
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/// Allows having using `suggestion` in the `#[deprecated]` attribute.

‎compiler/rustc_hir_analysis/src/collect/generics_of.rs‎

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@@ -338,8 +338,6 @@ pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Generics {
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if default.is_some() {
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match allow_defaults {
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Defaults::Allowed => {}
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Defaults::FutureCompatDisallowed
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if tcx.features().default_type_parameter_fallback => {}
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Defaults::FutureCompatDisallowed => {
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tcx.node_span_lint(
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lint::builtin::INVALID_TYPE_PARAM_DEFAULT,

‎compiler/rustc_lint_defs/src/builtin.rs‎

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@@ -1267,7 +1267,7 @@ declare_lint! {
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Deny,
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"type parameter default erroneously allowed in invalid location",
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@future_incompatible = FutureIncompatibleInfo {
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reason: FutureIncompatibilityReason::FutureReleaseErrorDontReportInDeps,
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reason: FutureIncompatibilityReason::FutureReleaseErrorReportInDeps,
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reference: "issue #36887 <https://github.com/rust-lang/rust/issues/36887>",
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};
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}

‎tests/ui/feature-gates/feature-gate-default_type_parameter_fallback.stderr‎

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This file was deleted.

‎tests/ui/impl-trait/where-allowed.stderr‎

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@@ -433,3 +433,25 @@ error: aborting due to 50 previous errors
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Some errors have detailed explanations: E0053, E0118, E0283, E0562, E0599, E0658, E0666.
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For more information about an error, try `rustc --explain E0053`.
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Future incompatibility report: Future breakage diagnostic:
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error: defaults for type parameters are only allowed in `struct`, `enum`, `type`, or `trait` definitions
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--> $DIR/where-allowed.rs:239:7
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|
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LL | impl <T = impl Debug> T {}
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| ^^^^^^^^^^^^^^
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|
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= warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
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= note: for more information, see issue #36887 <https://github.com/rust-lang/rust/issues/36887>
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= note: `#[deny(invalid_type_param_default)]` on by default
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Future breakage diagnostic:
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error: defaults for type parameters are only allowed in `struct`, `enum`, `type`, or `trait` definitions
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--> $DIR/where-allowed.rs:246:36
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|
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LL | fn in_method_generic_param_default<T = impl Debug>(_: T) {}
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| ^^^^^^^^^^^^^^
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|
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= warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
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= note: for more information, see issue #36887 <https://github.com/rust-lang/rust/issues/36887>
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= note: `#[deny(invalid_type_param_default)]` on by default
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‎tests/ui/issues/issue-26812.rs‎

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@@ -1,6 +1,6 @@
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#![feature(default_type_parameter_fallback)]
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fn avg<T=T::Item>(_: T) {}
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//~^ ERROR generic parameters with a default cannot use forward declared identifiers
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//~| ERROR defaults for type parameters
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//~| WARN previously accepted
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fn main() {}

‎tests/ui/issues/issue-26812.stderr‎

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@@ -1,9 +1,30 @@
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error[E0128]: generic parameters with a default cannot use forward declared identifiers
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--> $DIR/issue-26812.rs:3:10
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--> $DIR/issue-26812.rs:1:10
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|
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LL | fn avg<T=T::Item>(_: T) {}
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| ^^^^^^^ defaulted generic parameters cannot be forward declared
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error: aborting due to 1 previous error
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error: defaults for type parameters are only allowed in `struct`, `enum`, `type`, or `trait` definitions
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--> $DIR/issue-26812.rs:1:8
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|
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LL | fn avg<T=T::Item>(_: T) {}
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| ^^^^^^^^^
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|
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= warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
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= note: for more information, see issue #36887 <https://github.com/rust-lang/rust/issues/36887>
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= note: `#[deny(invalid_type_param_default)]` on by default
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error: aborting due to 2 previous errors
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For more information about this error, try `rustc --explain E0128`.
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Future incompatibility report: Future breakage diagnostic:
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error: defaults for type parameters are only allowed in `struct`, `enum`, `type`, or `trait` definitions
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--> $DIR/issue-26812.rs:1:8
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|
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LL | fn avg<T=T::Item>(_: T) {}
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| ^^^^^^^^^
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|
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= warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
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= note: for more information, see issue #36887 <https://github.com/rust-lang/rust/issues/36887>
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= note: `#[deny(invalid_type_param_default)]` on by default
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‎tests/ui/lifetimes/unusual-rib-combinations.stderr‎

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@@ -72,3 +72,14 @@ error: aborting due to 8 previous errors
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Some errors have detailed explanations: E0106, E0214, E0308, E0770.
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For more information about an error, try `rustc --explain E0106`.
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Future incompatibility report: Future breakage diagnostic:
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error: defaults for type parameters are only allowed in `struct`, `enum`, `type`, or `trait` definitions
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--> $DIR/unusual-rib-combinations.rs:15:6
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|
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LL | fn c<T = u8()>() {}
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| ^^^^^^^^
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|
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= warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
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= note: for more information, see issue #36887 <https://github.com/rust-lang/rust/issues/36887>
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= note: `#[deny(invalid_type_param_default)]` on by default
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‎tests/ui/type-inference/unbounded-type-param-in-fn-with-assoc-type.stderr‎

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@@ -12,3 +12,13 @@ LL | foo::<T, U>();
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error: aborting due to 1 previous error
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For more information about this error, try `rustc --explain E0282`.
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Future incompatibility report: Future breakage diagnostic:
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warning: defaults for type parameters are only allowed in `struct`, `enum`, `type`, or `trait` definitions
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--> $DIR/unbounded-type-param-in-fn-with-assoc-type.rs:3:11
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|
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LL | fn foo<T, U = u64>() -> (T, U) {
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| ^^^^^^^
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|
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= warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
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= note: for more information, see issue #36887 <https://github.com/rust-lang/rust/issues/36887>
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