Rollup merge of #101936 - IntQuant:issue-100717-infer-4, r=compiler-errors

Migrating rustc_infer to session diagnostics (part 3)

``@rustbot`` label +A-translation
r? rust-lang/diagnostics
cc https://github.com/rust-lang/rust/issues/100717

Seems like a part of static_impl_trait.rs emits suggestions in a loop, and note.rs needs to have two instances of the same subdiagnostic, so these will need to wait until we have eager translation/list support.
Other than that, there is only error_reporting/mod.rs left to migrate.

compiler/rustc_error_messages/locales/en-US/infer.ftl

@@ -172,3 +172,142 @@ infer_msl_unmet_req = because this has an unmet lifetime requirement
 infer_msl_trait_note = this has an implicit `'static` lifetime requirement
 infer_msl_trait_sugg = consider relaxing the implicit `'static` requirement
 infer_suggest_add_let_for_letchains = consider adding `let`
+
+infer_explicit_lifetime_required_with_ident = explicit lifetime required in the type of `{$simple_ident}`
+    .label = lifetime `{$named}` required
+
+infer_explicit_lifetime_required_with_param_type = explicit lifetime required in parameter type
+    .label = lifetime `{$named}` required
+
+infer_explicit_lifetime_required_sugg_with_ident = add explicit lifetime `{$named}` to the type of `{$simple_ident}`
+
+infer_explicit_lifetime_required_sugg_with_param_type = add explicit lifetime `{$named}` to type
+
+infer_actual_impl_expl_expected_signature_two = {$leading_ellipsis ->
+    [true] ...
+    *[false] {""}
+}closure with signature `{$ty_or_sig}` must implement `{$trait_path}`, for any two lifetimes `'{$lifetime_1}` and `'{$lifetime_2}`...
+infer_actual_impl_expl_expected_signature_any = {$leading_ellipsis ->
+    [true] ...
+    *[false] {""}
+}closure with signature `{$ty_or_sig}` must implement `{$trait_path}`, for any lifetime `'{$lifetime_1}`...
+infer_actual_impl_expl_expected_signature_some = {$leading_ellipsis ->
+    [true] ...
+    *[false] {""}
+}closure with signature `{$ty_or_sig}` must implement `{$trait_path}`, for some specific lifetime `'{lifetime_1}`...
+infer_actual_impl_expl_expected_signature_nothing = {$leading_ellipsis ->
+    [true] ...
+    *[false] {""}
+}closure with signature `{$ty_or_sig}` must implement `{$trait_path}`
+infer_actual_impl_expl_expected_passive_two = {$leading_ellipsis ->
+    [true] ...
+    *[false] {""}
+}`{$trait_path}` would have to be implemented for the type `{$ty_or_sig}`, for any two lifetimes `'{$lifetime_1}` and `'{$lifetime_2}`...
+infer_actual_impl_expl_expected_passive_any = {$leading_ellipsis ->
+    [true] ...
+    *[false] {""}
+}`{$trait_path}` would have to be implemented for the type `{$ty_or_sig}`, for any lifetime `'{$lifetime_1}`...
+infer_actual_impl_expl_expected_passive_some = {$leading_ellipsis ->
+    [true] ...
+    *[false] {""}
+}`{$trait_path}` would have to be implemented for the type `{$ty_or_sig}`, for some specific lifetime `'{lifetime_1}`...
+infer_actual_impl_expl_expected_passive_nothing = {$leading_ellipsis ->
+    [true] ...
+    *[false] {""}
+}`{$trait_path}` would have to be implemented for the type `{$ty_or_sig}`
+infer_actual_impl_expl_expected_other_two = {$leading_ellipsis ->
+    [true] ...
+    *[false] {""}
+}`{$ty_or_sig}` must implement `{$trait_path}`, for any two lifetimes `'{$lifetime_1}` and `'{$lifetime_2}`...
+infer_actual_impl_expl_expected_other_any = {$leading_ellipsis ->
+    [true] ...
+    *[false] {""}
+}`{$ty_or_sig}` must implement `{$trait_path}`, for any lifetime `'{$lifetime_1}`...
+infer_actual_impl_expl_expected_other_some = {$leading_ellipsis ->
+    [true] ...
+    *[false] {""}
+}`{$ty_or_sig}` must implement `{$trait_path}`, for some specific lifetime `'{lifetime_1}`...
+infer_actual_impl_expl_expected_other_nothing = {$leading_ellipsis ->
+    [true] ...
+    *[false] {""}
+}`{$ty_or_sig}` must implement `{$trait_path}`
+
+infer_actual_impl_expl_but_actually_implements_trait = ...but it actually implements `{$trait_path}`{$has_lifetime ->
+    [true] , for some specific lifetime `'{$lifetime}`
+    *[false] {""}
+}
+infer_actual_impl_expl_but_actually_implemented_for_ty = ...but `{$trait_path}` is actually implemented for the type `{$ty}`{$has_lifetime ->
+    [true] , for some specific lifetime `'{$lifetime}`
+    *[false] {""}
+}
+infer_actual_impl_expl_but_actually_ty_implements = ...but `{$ty}` actually implements `{$trait_path}`{$has_lifetime ->
+    [true] , for some specific lifetime `'{$lifetime}`
+    *[false] {""}
+}
+
+infer_trait_placeholder_mismatch = implementation of `{$trait_def_id}` is not general enough
+    .label_satisfy = doesn't satisfy where-clause
+    .label_where = due to a where-clause on `{$def_id}`...
+    .label_dup = implementation of `{$trait_def_id}` is not general enough
+
+infer_trait_impl_diff = `impl` item signature doesn't match `trait` item signature
+    .found = found `{$found}`
+    .expected = expected `{$expected}`
+    .expected_found = expected `{$expected}`
+               {"   "}found `{$found}`
+
+infer_tid_rel_help = verify the lifetime relationships in the `trait` and `impl` between the `self` argument, the other inputs and its output
+infer_tid_consider_borrowing = consider borrowing this type parameter in the trait
+infer_tid_param_help = the lifetime requirements from the `impl` do not correspond to the requirements in the `trait`
+
+infer_dtcs_has_lifetime_req_label = this has an implicit `'static` lifetime requirement
+infer_dtcs_introduces_requirement = calling this method introduces the `impl`'s 'static` requirement
+infer_dtcs_has_req_note = the used `impl` has a `'static` requirement
+infer_dtcs_suggestion = consider relaxing the implicit `'static` requirement
+
+infer_but_calling_introduces = {$has_param_name ->
+    [true] `{$param_name}`
+    *[false] `fn` parameter
+} has {$lifetime_kind ->
+    [named] lifetime `{lifetime}`
+    *[anon] an anonymous lifetime `'_`
+} but calling `{assoc_item}` introduces an implicit `'static` lifetime requirement
+    .label1 = {$has_lifetime ->
+        [named] lifetime `{lifetime}`
+        *[anon] an anonymous lifetime `'_`
+    }
+    .label2 = ...is used and required to live as long as `'static` here because of an implicit lifetime bound on the {$has_impl_path ->
+        [named] `impl` of `{$impl_path}`
+        *[anon] inherent `impl`
+    }
+
+infer_but_needs_to_satisfy = {$has_param_name ->
+    [true] `{$param_name}`
+    *[false] `fn` parameter
+} has {$has_lifetime ->
+    [named] lifetime `{lifetime}`
+    *[anon] an anonymous lifetime `'_`
+} but it needs to satisfy a `'static` lifetime requirement
+    .influencer = this data with {$has_lifetime ->
+        [named] lifetime `{lifetime}`
+        *[anon] an anonymous lifetime `'_`
+    }...
+    .require = {$spans_empty ->
+        *[true] ...is used and required to live as long as `'static` here
+        [false] ...and is required to live as long as `'static` here
+    }
+    .used_here = ...is used here...
+    .introduced_by_bound = 'static` lifetime requirement introduced by this bound
+
+infer_more_targeted = {$has_param_name ->
+    [true] `{$param_name}`
+    *[false] `fn` parameter
+} has {$has_lifetime ->
+    [named] lifetime `{lifetime}`
+    *[anon] an anonymous lifetime `'_`
+} but calling `{$ident}` introduces an implicit `'static` lifetime requirement
+
+infer_ril_introduced_here = `'static` requirement introduced here
+infer_ril_introduced_by = requirement introduced by this return type
+infer_ril_because_of = because of this returned expression
+infer_ril_static_introduced_by = "`'static` lifetime requirement introduced by the return type

compiler/rustc_infer/src/errors/mod.rs

@@ -1,15 +1,18 @@
 use hir::GenericParamKind;
 use rustc_errors::{
     fluent, AddToDiagnostic, Applicability, Diagnostic, DiagnosticMessage, DiagnosticStyledString,
-    MultiSpan, SubdiagnosticMessage,
+    IntoDiagnosticArg, MultiSpan, SubdiagnosticMessage,
 };
 use rustc_hir as hir;
-use rustc_hir::{FnRetTy, Ty};
+use rustc_hir::FnRetTy;
 use rustc_macros::{Diagnostic, Subdiagnostic};
-use rustc_middle::ty::{Region, TyCtxt};
+use rustc_middle::ty::print::TraitRefPrintOnlyTraitPath;
+use rustc_middle::ty::{Binder, FnSig, Region, Ty, TyCtxt};
 use rustc_span::symbol::kw;
+use rustc_span::Symbol;
 use rustc_span::{symbol::Ident, BytePos, Span};
 
+use crate::infer::error_reporting::nice_region_error::placeholder_error::Highlighted;
 use crate::infer::error_reporting::{
     need_type_info::{GeneratorKindAsDiagArg, UnderspecifiedArgKind},
     ObligationCauseAsDiagArg,
@@ -357,8 +360,8 @@ impl AddToDiagnostic for LifetimeMismatchLabels {
 pub struct AddLifetimeParamsSuggestion<'a> {
     pub tcx: TyCtxt<'a>,
     pub sub: Region<'a>,
-    pub ty_sup: &'a Ty<'a>,
+    pub ty_sup: &'a hir::Ty<'a>,
-    pub ty_sub: &'a Ty<'a>,
+    pub ty_sub: &'a hir::Ty<'a>,
     pub add_note: bool,
 }
 
@@ -520,3 +523,411 @@ pub struct MismatchedStaticLifetime<'a> {
     #[subdiagnostic]
     pub implicit_static_lifetimes: Vec<ImplicitStaticLifetimeSubdiag>,
 }
+
+#[derive(Diagnostic)]
+pub enum ExplicitLifetimeRequired<'a> {
+    #[diag(infer_explicit_lifetime_required_with_ident, code = "E0621")]
+    WithIdent {
+        #[primary_span]
+        #[label]
+        span: Span,
+        simple_ident: Ident,
+        named: String,
+        #[suggestion(
+            infer_explicit_lifetime_required_sugg_with_ident,
+            code = "{new_ty}",
+            applicability = "unspecified"
+        )]
+        new_ty_span: Span,
+        #[skip_arg]
+        new_ty: Ty<'a>,
+    },
+    #[diag(infer_explicit_lifetime_required_with_param_type, code = "E0621")]
+    WithParamType {
+        #[primary_span]
+        #[label]
+        span: Span,
+        named: String,
+        #[suggestion(
+            infer_explicit_lifetime_required_sugg_with_param_type,
+            code = "{new_ty}",
+            applicability = "unspecified"
+        )]
+        new_ty_span: Span,
+        #[skip_arg]
+        new_ty: Ty<'a>,
+    },
+}
+
+pub enum TyOrSig<'tcx> {
+    Ty(Highlighted<'tcx, Ty<'tcx>>),
+    ClosureSig(Highlighted<'tcx, Binder<'tcx, FnSig<'tcx>>>),
+}
+
+impl IntoDiagnosticArg for TyOrSig<'_> {
+    fn into_diagnostic_arg(self) -> rustc_errors::DiagnosticArgValue<'static> {
+        match self {
+            TyOrSig::Ty(ty) => ty.into_diagnostic_arg(),
+            TyOrSig::ClosureSig(sig) => sig.into_diagnostic_arg(),
+        }
+    }
+}
+
+#[derive(Subdiagnostic)]
+pub enum ActualImplExplNotes<'tcx> {
+    #[note(infer_actual_impl_expl_expected_signature_two)]
+    ExpectedSignatureTwo {
+        leading_ellipsis: bool,
+        ty_or_sig: TyOrSig<'tcx>,
+        trait_path: Highlighted<'tcx, TraitRefPrintOnlyTraitPath<'tcx>>,
+        lifetime_1: usize,
+        lifetime_2: usize,
+    },
+    #[note(infer_actual_impl_expl_expected_signature_any)]
+    ExpectedSignatureAny {
+        leading_ellipsis: bool,
+        ty_or_sig: TyOrSig<'tcx>,
+        trait_path: Highlighted<'tcx, TraitRefPrintOnlyTraitPath<'tcx>>,
+        lifetime_1: usize,
+    },
+    #[note(infer_actual_impl_expl_expected_signature_some)]
+    ExpectedSignatureSome {
+        leading_ellipsis: bool,
+        ty_or_sig: TyOrSig<'tcx>,
+        trait_path: Highlighted<'tcx, TraitRefPrintOnlyTraitPath<'tcx>>,
+        lifetime_1: usize,
+    },
+    #[note(infer_actual_impl_expl_expected_signature_nothing)]
+    ExpectedSignatureNothing {
+        leading_ellipsis: bool,
+        ty_or_sig: TyOrSig<'tcx>,
+        trait_path: Highlighted<'tcx, TraitRefPrintOnlyTraitPath<'tcx>>,
+    },
+    #[note(infer_actual_impl_expl_expected_passive_two)]
+    ExpectedPassiveTwo {
+        leading_ellipsis: bool,
+        ty_or_sig: TyOrSig<'tcx>,
+        trait_path: Highlighted<'tcx, TraitRefPrintOnlyTraitPath<'tcx>>,
+        lifetime_1: usize,
+        lifetime_2: usize,
+    },
+    #[note(infer_actual_impl_expl_expected_passive_any)]
+    ExpectedPassiveAny {
+        leading_ellipsis: bool,
+        ty_or_sig: TyOrSig<'tcx>,
+        trait_path: Highlighted<'tcx, TraitRefPrintOnlyTraitPath<'tcx>>,
+        lifetime_1: usize,
+    },
+    #[note(infer_actual_impl_expl_expected_passive_some)]
+    ExpectedPassiveSome {
+        leading_ellipsis: bool,
+        ty_or_sig: TyOrSig<'tcx>,
+        trait_path: Highlighted<'tcx, TraitRefPrintOnlyTraitPath<'tcx>>,
+        lifetime_1: usize,
+    },
+    #[note(infer_actual_impl_expl_expected_passive_nothing)]
+    ExpectedPassiveNothing {
+        leading_ellipsis: bool,
+        ty_or_sig: TyOrSig<'tcx>,
+        trait_path: Highlighted<'tcx, TraitRefPrintOnlyTraitPath<'tcx>>,
+    },
+    #[note(infer_actual_impl_expl_expected_other_two)]
+    ExpectedOtherTwo {
+        leading_ellipsis: bool,
+        ty_or_sig: TyOrSig<'tcx>,
+        trait_path: Highlighted<'tcx, TraitRefPrintOnlyTraitPath<'tcx>>,
+        lifetime_1: usize,
+        lifetime_2: usize,
+    },
+    #[note(infer_actual_impl_expl_expected_other_any)]
+    ExpectedOtherAny {
+        leading_ellipsis: bool,
+        ty_or_sig: TyOrSig<'tcx>,
+        trait_path: Highlighted<'tcx, TraitRefPrintOnlyTraitPath<'tcx>>,
+        lifetime_1: usize,
+    },
+    #[note(infer_actual_impl_expl_expected_other_some)]
+    ExpectedOtherSome {
+        leading_ellipsis: bool,
+        ty_or_sig: TyOrSig<'tcx>,
+        trait_path: Highlighted<'tcx, TraitRefPrintOnlyTraitPath<'tcx>>,
+        lifetime_1: usize,
+    },
+    #[note(infer_actual_impl_expl_expected_other_nothing)]
+    ExpectedOtherNothing {
+        leading_ellipsis: bool,
+        ty_or_sig: TyOrSig<'tcx>,
+        trait_path: Highlighted<'tcx, TraitRefPrintOnlyTraitPath<'tcx>>,
+    },
+    #[note(infer_actual_impl_expl_but_actually_implements_trait)]
+    ButActuallyImplementsTrait {
+        trait_path: Highlighted<'tcx, TraitRefPrintOnlyTraitPath<'tcx>>,
+        has_lifetime: bool,
+        lifetime: usize,
+    },
+    #[note(infer_actual_impl_expl_but_actually_implemented_for_ty)]
+    ButActuallyImplementedForTy {
+        trait_path: Highlighted<'tcx, TraitRefPrintOnlyTraitPath<'tcx>>,
+        has_lifetime: bool,
+        lifetime: usize,
+        ty: String,
+    },
+    #[note(infer_actual_impl_expl_but_actually_ty_implements)]
+    ButActuallyTyImplements {
+        trait_path: Highlighted<'tcx, TraitRefPrintOnlyTraitPath<'tcx>>,
+        has_lifetime: bool,
+        lifetime: usize,
+        ty: String,
+    },
+}
+
+pub enum ActualImplExpectedKind {
+    Signature,
+    Passive,
+    Other,
+}
+
+pub enum ActualImplExpectedLifetimeKind {
+    Two,
+    Any,
+    Some,
+    Nothing,
+}
+
+impl<'tcx> ActualImplExplNotes<'tcx> {
+    pub fn new_expected(
+        kind: ActualImplExpectedKind,
+        lt_kind: ActualImplExpectedLifetimeKind,
+        leading_ellipsis: bool,
+        ty_or_sig: TyOrSig<'tcx>,
+        trait_path: Highlighted<'tcx, TraitRefPrintOnlyTraitPath<'tcx>>,
+        lifetime_1: usize,
+        lifetime_2: usize,
+    ) -> Self {
+        match (kind, lt_kind) {
+            (ActualImplExpectedKind::Signature, ActualImplExpectedLifetimeKind::Two) => {
+                Self::ExpectedSignatureTwo {
+                    leading_ellipsis,
+                    ty_or_sig,
+                    trait_path,
+                    lifetime_1,
+                    lifetime_2,
+                }
+            }
+            (ActualImplExpectedKind::Signature, ActualImplExpectedLifetimeKind::Any) => {
+                Self::ExpectedSignatureAny { leading_ellipsis, ty_or_sig, trait_path, lifetime_1 }
+            }
+            (ActualImplExpectedKind::Signature, ActualImplExpectedLifetimeKind::Some) => {
+                Self::ExpectedSignatureSome { leading_ellipsis, ty_or_sig, trait_path, lifetime_1 }
+            }
+            (ActualImplExpectedKind::Signature, ActualImplExpectedLifetimeKind::Nothing) => {
+                Self::ExpectedSignatureNothing { leading_ellipsis, ty_or_sig, trait_path }
+            }
+            (ActualImplExpectedKind::Passive, ActualImplExpectedLifetimeKind::Two) => {
+                Self::ExpectedPassiveTwo {
+                    leading_ellipsis,
+                    ty_or_sig,
+                    trait_path,
+                    lifetime_1,
+                    lifetime_2,
+                }
+            }
+            (ActualImplExpectedKind::Passive, ActualImplExpectedLifetimeKind::Any) => {
+                Self::ExpectedPassiveAny { leading_ellipsis, ty_or_sig, trait_path, lifetime_1 }
+            }
+            (ActualImplExpectedKind::Passive, ActualImplExpectedLifetimeKind::Some) => {
+                Self::ExpectedPassiveSome { leading_ellipsis, ty_or_sig, trait_path, lifetime_1 }
+            }
+            (ActualImplExpectedKind::Passive, ActualImplExpectedLifetimeKind::Nothing) => {
+                Self::ExpectedPassiveNothing { leading_ellipsis, ty_or_sig, trait_path }
+            }
+            (ActualImplExpectedKind::Other, ActualImplExpectedLifetimeKind::Two) => {
+                Self::ExpectedOtherTwo {
+                    leading_ellipsis,
+                    ty_or_sig,
+                    trait_path,
+                    lifetime_1,
+                    lifetime_2,
+                }
+            }
+            (ActualImplExpectedKind::Other, ActualImplExpectedLifetimeKind::Any) => {
+                Self::ExpectedOtherAny { leading_ellipsis, ty_or_sig, trait_path, lifetime_1 }
+            }
+            (ActualImplExpectedKind::Other, ActualImplExpectedLifetimeKind::Some) => {
+                Self::ExpectedOtherSome { leading_ellipsis, ty_or_sig, trait_path, lifetime_1 }
+            }
+            (ActualImplExpectedKind::Other, ActualImplExpectedLifetimeKind::Nothing) => {
+                Self::ExpectedOtherNothing { leading_ellipsis, ty_or_sig, trait_path }
+            }
+        }
+    }
+}
+
+#[derive(Diagnostic)]
+#[diag(infer_trait_placeholder_mismatch)]
+pub struct TraitPlaceholderMismatch<'tcx> {
+    #[primary_span]
+    pub span: Span,
+    #[label(label_satisfy)]
+    pub satisfy_span: Option<Span>,
+    #[label(label_where)]
+    pub where_span: Option<Span>,
+    #[label(label_dup)]
+    pub dup_span: Option<Span>,
+    pub def_id: String,
+    pub trait_def_id: String,
+
+    #[subdiagnostic]
+    pub actual_impl_expl_notes: Vec<ActualImplExplNotes<'tcx>>,
+}
+
+pub struct ConsiderBorrowingParamHelp {
+    pub spans: Vec<Span>,
+}
+
+impl AddToDiagnostic for ConsiderBorrowingParamHelp {
+    fn add_to_diagnostic_with<F>(self, diag: &mut Diagnostic, f: F)
+    where
+        F: Fn(&mut Diagnostic, SubdiagnosticMessage) -> SubdiagnosticMessage,
+    {
+        let mut type_param_span: MultiSpan = self.spans.clone().into();
+        for &span in &self.spans {
+            // Seems like we can't call f() here as Into<DiagnosticMessage> is required
+            type_param_span.push_span_label(span, fluent::infer_tid_consider_borrowing);
+        }
+        let msg = f(diag, fluent::infer_tid_param_help.into());
+        diag.span_help(type_param_span, msg);
+    }
+}
+
+#[derive(Subdiagnostic)]
+#[help(infer_tid_rel_help)]
+pub struct RelationshipHelp;
+
+#[derive(Diagnostic)]
+#[diag(infer_trait_impl_diff)]
+pub struct TraitImplDiff {
+    #[primary_span]
+    #[label(found)]
+    pub sp: Span,
+    #[label(expected)]
+    pub trait_sp: Span,
+    #[note(expected_found)]
+    pub note: (),
+    #[subdiagnostic]
+    pub param_help: ConsiderBorrowingParamHelp,
+    #[subdiagnostic]
+    // Seems like subdiagnostics are always pushed to the end, so this one
+    // also has to be a subdiagnostic to maintain order.
+    pub rel_help: Option<RelationshipHelp>,
+    pub expected: String,
+    pub found: String,
+}
+
+pub struct DynTraitConstraintSuggestion {
+    pub span: Span,
+    pub ident: Ident,
+}
+
+impl AddToDiagnostic for DynTraitConstraintSuggestion {
+    fn add_to_diagnostic_with<F>(self, diag: &mut Diagnostic, f: F)
+    where
+        F: Fn(&mut Diagnostic, SubdiagnosticMessage) -> SubdiagnosticMessage,
+    {
+        let mut multi_span: MultiSpan = vec![self.span].into();
+        multi_span.push_span_label(self.span, fluent::infer_dtcs_has_lifetime_req_label);
+        multi_span.push_span_label(self.ident.span, fluent::infer_dtcs_introduces_requirement);
+        let msg = f(diag, fluent::infer_dtcs_has_req_note.into());
+        diag.span_note(multi_span, msg);
+        let msg = f(diag, fluent::infer_dtcs_suggestion.into());
+        diag.span_suggestion_verbose(
+            self.span.shrink_to_hi(),
+            msg,
+            " + '_",
+            Applicability::MaybeIncorrect,
+        );
+    }
+}
+
+#[derive(Diagnostic)]
+#[diag(infer_but_calling_introduces, code = "E0772")]
+pub struct ButCallingIntroduces {
+    #[label(label1)]
+    pub param_ty_span: Span,
+    #[primary_span]
+    #[label(label2)]
+    pub cause_span: Span,
+
+    pub has_param_name: bool,
+    pub param_name: String,
+    pub has_lifetime: bool,
+    pub lifetime: String,
+    pub assoc_item: Symbol,
+    pub has_impl_path: bool,
+    pub impl_path: String,
+}
+
+pub struct ReqIntroducedLocations {
+    pub span: MultiSpan,
+    pub spans: Vec<Span>,
+    pub fn_decl_span: Span,
+    pub cause_span: Span,
+    pub add_label: bool,
+}
+
+impl AddToDiagnostic for ReqIntroducedLocations {
+    fn add_to_diagnostic_with<F>(mut self, diag: &mut Diagnostic, f: F)
+    where
+        F: Fn(&mut Diagnostic, SubdiagnosticMessage) -> SubdiagnosticMessage,
+    {
+        for sp in self.spans {
+            self.span.push_span_label(sp, fluent::infer_ril_introduced_here);
+        }
+
+        if self.add_label {
+            self.span.push_span_label(self.fn_decl_span, fluent::infer_ril_introduced_by);
+        }
+        self.span.push_span_label(self.cause_span, fluent::infer_ril_because_of);
+        let msg = f(diag, fluent::infer_ril_static_introduced_by.into());
+        diag.span_note(self.span, msg);
+    }
+}
+
+pub struct MoreTargeted {
+    pub ident: Symbol,
+}
+
+impl AddToDiagnostic for MoreTargeted {
+    fn add_to_diagnostic_with<F>(self, diag: &mut Diagnostic, _f: F)
+    where
+        F: Fn(&mut Diagnostic, SubdiagnosticMessage) -> SubdiagnosticMessage,
+    {
+        diag.code(rustc_errors::error_code!(E0772));
+        diag.set_primary_message(fluent::infer_more_targeted);
+        diag.set_arg("ident", self.ident);
+    }
+}
+
+#[derive(Diagnostic)]
+#[diag(infer_but_needs_to_satisfy, code = "E0759")]
+pub struct ButNeedsToSatisfy {
+    #[primary_span]
+    pub sp: Span,
+    #[label(influencer)]
+    pub influencer_point: Span,
+    #[label(used_here)]
+    pub spans: Vec<Span>,
+    #[label(require)]
+    pub require_span_as_label: Option<Span>,
+    #[note(require)]
+    pub require_span_as_note: Option<Span>,
+    #[note(introduced_by_bound)]
+    pub bound: Option<Span>,
+
+    #[subdiagnostic]
+    pub req_introduces_loc: Option<ReqIntroducedLocations>,
+
+    pub spans_empty: bool,
+    pub has_lifetime: bool,
+    pub lifetime: String,
+}

compiler/rustc_infer/src/infer/error_reporting/nice_region_error/mod.rs

@@ -9,7 +9,7 @@ mod different_lifetimes;
 pub mod find_anon_type;
 mod mismatched_static_lifetime;
 mod named_anon_conflict;
-mod placeholder_error;
+pub(crate) mod placeholder_error;
 mod placeholder_relation;
 mod static_impl_trait;
 mod trait_impl_difference;

compiler/rustc_infer/src/infer/error_reporting/nice_region_error/named_anon_conflict.rs

@@ -1,8 +1,11 @@
 //! Error Reporting for Anonymous Region Lifetime Errors
 //! where one region is named and the other is anonymous.
-use crate::infer::error_reporting::nice_region_error::find_anon_type::find_anon_type;
 use crate::infer::error_reporting::nice_region_error::NiceRegionError;
-use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder, ErrorGuaranteed};
+use crate::{
+    errors::ExplicitLifetimeRequired,
+    infer::error_reporting::nice_region_error::find_anon_type::find_anon_type,
+};
+use rustc_errors::{DiagnosticBuilder, ErrorGuaranteed};
 use rustc_middle::ty;
 use rustc_span::symbol::kw;
 
@@ -86,31 +89,17 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
         {
             return None;
         }
-
+        let named = named.to_string();
-        let (error_var, span_label_var) = match param.pat.simple_ident() {
+        let err = match param.pat.simple_ident() {
-            Some(simple_ident) => (
+            Some(simple_ident) => ExplicitLifetimeRequired::WithIdent {
-                format!("the type of `{}`", simple_ident),
+                span,
-                format!("the type of `{}`", simple_ident),
+                simple_ident,
-            ),
+                named,
-            None => ("parameter type".to_owned(), "type".to_owned()),
+                new_ty_span,
+                new_ty,
+            },
+            None => ExplicitLifetimeRequired::WithParamType { span, named, new_ty_span, new_ty },
         };
-
+        Some(self.tcx().sess.parse_sess.create_err(err))
-        let mut diag = struct_span_err!(
-            self.tcx().sess,
-            span,
-            E0621,
-            "explicit lifetime required in {}",
-            error_var
-        );
-
-        diag.span_label(span, format!("lifetime `{}` required", named));
-        diag.span_suggestion(
-            new_ty_span,
-            &format!("add explicit lifetime `{}` to {}", named, span_label_var),
-            new_ty,
-            Applicability::Unspecified,
-        );
-
-        Some(diag)
     }
 }

compiler/rustc_infer/src/infer/error_reporting/nice_region_error/placeholder_error.rs

@@ -1,10 +1,14 @@
+use crate::errors::{
+    ActualImplExpectedKind, ActualImplExpectedLifetimeKind, ActualImplExplNotes,
+    TraitPlaceholderMismatch, TyOrSig,
+};
 use crate::infer::error_reporting::nice_region_error::NiceRegionError;
 use crate::infer::lexical_region_resolve::RegionResolutionError;
 use crate::infer::ValuePairs;
 use crate::infer::{SubregionOrigin, TypeTrace};
 use crate::traits::{ObligationCause, ObligationCauseCode};
 use rustc_data_structures::intern::Interned;
-use rustc_errors::{Diagnostic, DiagnosticBuilder, ErrorGuaranteed};
+use rustc_errors::{DiagnosticBuilder, ErrorGuaranteed, IntoDiagnosticArg};
 use rustc_hir::def::Namespace;
 use rustc_hir::def_id::DefId;
 use rustc_middle::ty::error::ExpectedFound;
@@ -12,7 +16,43 @@ use rustc_middle::ty::print::{FmtPrinter, Print, RegionHighlightMode};
 use rustc_middle::ty::subst::SubstsRef;
 use rustc_middle::ty::{self, RePlaceholder, ReVar, Region, TyCtxt};
 
-use std::fmt::{self, Write};
+use std::fmt;
+
+// HACK(eddyb) maybe move this in a more central location.
+#[derive(Copy, Clone)]
+pub struct Highlighted<'tcx, T> {
+    tcx: TyCtxt<'tcx>,
+    highlight: RegionHighlightMode<'tcx>,
+    value: T,
+}
+
+impl<'tcx, T> IntoDiagnosticArg for Highlighted<'tcx, T>
+where
+    T: for<'a> Print<'tcx, FmtPrinter<'a, 'tcx>, Error = fmt::Error, Output = FmtPrinter<'a, 'tcx>>,
+{
+    fn into_diagnostic_arg(self) -> rustc_errors::DiagnosticArgValue<'static> {
+        rustc_errors::DiagnosticArgValue::Str(self.to_string().into())
+    }
+}
+
+impl<'tcx, T> Highlighted<'tcx, T> {
+    fn map<U>(self, f: impl FnOnce(T) -> U) -> Highlighted<'tcx, U> {
+        Highlighted { tcx: self.tcx, highlight: self.highlight, value: f(self.value) }
+    }
+}
+
+impl<'tcx, T> fmt::Display for Highlighted<'tcx, T>
+where
+    T: for<'a> Print<'tcx, FmtPrinter<'a, 'tcx>, Error = fmt::Error, Output = FmtPrinter<'a, 'tcx>>,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let mut printer = ty::print::FmtPrinter::new(self.tcx, Namespace::TypeNS);
+        printer.region_highlight_mode = self.highlight;
+
+        let s = self.value.print(printer)?.into_buffer();
+        f.write_str(&s)
+    }
+}
 
 impl<'tcx> NiceRegionError<'_, 'tcx> {
     /// When given a `ConcreteFailure` for a function with arguments containing a named region and
@@ -205,26 +245,21 @@ impl<'tcx> NiceRegionError<'_, 'tcx> {
         actual_substs: SubstsRef<'tcx>,
     ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
         let span = cause.span();
-        let msg = format!(
-            "implementation of `{}` is not general enough",
-            self.tcx().def_path_str(trait_def_id),
-        );
-        let mut err = self.tcx().sess.struct_span_err(span, &msg);
 
-        let leading_ellipsis = if let ObligationCauseCode::ItemObligation(def_id)
+        let (leading_ellipsis, satisfy_span, where_span, dup_span, def_id) =
-        | ObligationCauseCode::ExprItemObligation(def_id, ..) =
+            if let ObligationCauseCode::ItemObligation(def_id)
-            *cause.code()
+            | ObligationCauseCode::ExprItemObligation(def_id, ..) = *cause.code()
-        {
+            {
-            err.span_label(span, "doesn't satisfy where-clause");
+                (
-            err.span_label(
+                    true,
-                self.tcx().def_span(def_id),
+                    Some(span),
-                &format!("due to a where-clause on `{}`...", self.tcx().def_path_str(def_id)),
+                    Some(self.tcx().def_span(def_id)),
-            );
+                    None,
-            true
+                    self.tcx().def_path_str(def_id),
-        } else {
+                )
-            err.span_label(span, &msg);
+            } else {
-            false
+                (false, None, None, Some(span), String::new())
-        };
+            };
 
         let expected_trait_ref = self
             .cx
@@ -284,8 +319,7 @@ impl<'tcx> NiceRegionError<'_, 'tcx> {
             ?expected_self_ty_has_vid,
         );
 
-        self.explain_actual_impl_that_was_found(
+        let actual_impl_expl_notes = self.explain_actual_impl_that_was_found(
-            &mut err,
             sub_placeholder,
             sup_placeholder,
             has_sub,
@@ -299,7 +333,15 @@ impl<'tcx> NiceRegionError<'_, 'tcx> {
             leading_ellipsis,
         );
 
-        err
+        self.tcx().sess.create_err(TraitPlaceholderMismatch {
+            span,
+            satisfy_span,
+            where_span,
+            dup_span,
+            def_id,
+            trait_def_id: self.tcx().def_path_str(trait_def_id),
+            actual_impl_expl_notes,
+        })
     }
 
     /// Add notes with details about the expected and actual trait refs, with attention to cases
@@ -309,7 +351,6 @@ impl<'tcx> NiceRegionError<'_, 'tcx> {
     /// due to the number of combinations we have to deal with.
     fn explain_actual_impl_that_was_found(
         &self,
-        err: &mut Diagnostic,
         sub_placeholder: Option<Region<'tcx>>,
         sup_placeholder: Option<Region<'tcx>>,
         has_sub: Option<usize>,
@@ -321,39 +362,7 @@ impl<'tcx> NiceRegionError<'_, 'tcx> {
         actual_has_vid: Option<usize>,
         any_self_ty_has_vid: bool,
         leading_ellipsis: bool,
-    ) {
+    ) -> Vec<ActualImplExplNotes<'tcx>> {
-        // HACK(eddyb) maybe move this in a more central location.
-        #[derive(Copy, Clone)]
-        struct Highlighted<'tcx, T> {
-            tcx: TyCtxt<'tcx>,
-            highlight: RegionHighlightMode<'tcx>,
-            value: T,
-        }
-
-        impl<'tcx, T> Highlighted<'tcx, T> {
-            fn map<U>(self, f: impl FnOnce(T) -> U) -> Highlighted<'tcx, U> {
-                Highlighted { tcx: self.tcx, highlight: self.highlight, value: f(self.value) }
-            }
-        }
-
-        impl<'tcx, T> fmt::Display for Highlighted<'tcx, T>
-        where
-            T: for<'a> Print<
-                'tcx,
-                FmtPrinter<'a, 'tcx>,
-                Error = fmt::Error,
-                Output = FmtPrinter<'a, 'tcx>,
-            >,
-        {
-            fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-                let mut printer = ty::print::FmtPrinter::new(self.tcx, Namespace::TypeNS);
-                printer.region_highlight_mode = self.highlight;
-
-                let s = self.value.print(printer)?.into_buffer();
-                f.write_str(&s)
-            }
-        }
-
         // The weird thing here with the `maybe_highlighting_region` calls and the
         // the match inside is meant to be like this:
         //
@@ -380,120 +389,110 @@ impl<'tcx> NiceRegionError<'_, 'tcx> {
         let mut expected_trait_ref = highlight_trait_ref(expected_trait_ref);
         expected_trait_ref.highlight.maybe_highlighting_region(sub_placeholder, has_sub);
         expected_trait_ref.highlight.maybe_highlighting_region(sup_placeholder, has_sup);
-        err.note(&{
-            let passive_voice = match (has_sub, has_sup) {
-                (Some(_), _) | (_, Some(_)) => any_self_ty_has_vid,
-                (None, None) => {
-                    expected_trait_ref.highlight.maybe_highlighting_region(vid, expected_has_vid);
-                    match expected_has_vid {
-                        Some(_) => true,
-                        None => any_self_ty_has_vid,
-                    }
-                }
-            };
 
-            let mut note = if same_self_type {
+        let passive_voice = match (has_sub, has_sup) {
-                let mut self_ty = expected_trait_ref.map(|tr| tr.self_ty());
+            (Some(_), _) | (_, Some(_)) => any_self_ty_has_vid,
-                self_ty.highlight.maybe_highlighting_region(vid, actual_has_vid);
+            (None, None) => {
-
+                expected_trait_ref.highlight.maybe_highlighting_region(vid, expected_has_vid);
-                if self_ty.value.is_closure()
+                match expected_has_vid {
-                    && self.tcx().is_fn_trait(expected_trait_ref.value.def_id)
+                    Some(_) => true,
-                {
+                    None => any_self_ty_has_vid,
-                    let closure_sig = self_ty.map(|closure| {
-                        if let ty::Closure(_, substs) = closure.kind() {
-                            self.tcx().signature_unclosure(
-                                substs.as_closure().sig(),
-                                rustc_hir::Unsafety::Normal,
-                            )
-                        } else {
-                            bug!("type is not longer closure");
-                        }
-                    });
-
-                    format!(
-                        "{}closure with signature `{}` must implement `{}`",
-                        if leading_ellipsis { "..." } else { "" },
-                        closure_sig,
-                        expected_trait_ref.map(|tr| tr.print_only_trait_path()),
-                    )
-                } else {
-                    format!(
-                        "{}`{}` must implement `{}`",
-                        if leading_ellipsis { "..." } else { "" },
-                        self_ty,
-                        expected_trait_ref.map(|tr| tr.print_only_trait_path()),
-                    )
-                }
-            } else if passive_voice {
-                format!(
-                    "{}`{}` would have to be implemented for the type `{}`",
-                    if leading_ellipsis { "..." } else { "" },
-                    expected_trait_ref.map(|tr| tr.print_only_trait_path()),
-                    expected_trait_ref.map(|tr| tr.self_ty()),
-                )
-            } else {
-                format!(
-                    "{}`{}` must implement `{}`",
-                    if leading_ellipsis { "..." } else { "" },
-                    expected_trait_ref.map(|tr| tr.self_ty()),
-                    expected_trait_ref.map(|tr| tr.print_only_trait_path()),
-                )
-            };
-
-            match (has_sub, has_sup) {
-                (Some(n1), Some(n2)) => {
-                    let _ = write!(
-                        note,
-                        ", for any two lifetimes `'{}` and `'{}`...",
-                        std::cmp::min(n1, n2),
-                        std::cmp::max(n1, n2),
-                    );
-                }
-                (Some(n), _) | (_, Some(n)) => {
-                    let _ = write!(note, ", for any lifetime `'{}`...", n,);
-                }
-                (None, None) => {
-                    if let Some(n) = expected_has_vid {
-                        let _ = write!(note, ", for some specific lifetime `'{}`...", n,);
-                    }
                 }
             }
+        };
 
-            note
+        let (kind, ty_or_sig, trait_path) = if same_self_type {
-        });
+            let mut self_ty = expected_trait_ref.map(|tr| tr.self_ty());
+            self_ty.highlight.maybe_highlighting_region(vid, actual_has_vid);
+
+            if self_ty.value.is_closure() && self.tcx().is_fn_trait(expected_trait_ref.value.def_id)
+            {
+                let closure_sig = self_ty.map(|closure| {
+                    if let ty::Closure(_, substs) = closure.kind() {
+                        self.tcx().signature_unclosure(
+                            substs.as_closure().sig(),
+                            rustc_hir::Unsafety::Normal,
+                        )
+                    } else {
+                        bug!("type is not longer closure");
+                    }
+                });
+                (
+                    ActualImplExpectedKind::Signature,
+                    TyOrSig::ClosureSig(closure_sig),
+                    expected_trait_ref.map(|tr| tr.print_only_trait_path()),
+                )
+            } else {
+                (
+                    ActualImplExpectedKind::Other,
+                    TyOrSig::Ty(self_ty),
+                    expected_trait_ref.map(|tr| tr.print_only_trait_path()),
+                )
+            }
+        } else if passive_voice {
+            (
+                ActualImplExpectedKind::Passive,
+                TyOrSig::Ty(expected_trait_ref.map(|tr| tr.self_ty())),
+                expected_trait_ref.map(|tr| tr.print_only_trait_path()),
+            )
+        } else {
+            (
+                ActualImplExpectedKind::Other,
+                TyOrSig::Ty(expected_trait_ref.map(|tr| tr.self_ty())),
+                expected_trait_ref.map(|tr| tr.print_only_trait_path()),
+            )
+        };
+
+        let (lt_kind, lifetime_1, lifetime_2) = match (has_sub, has_sup) {
+            (Some(n1), Some(n2)) => {
+                (ActualImplExpectedLifetimeKind::Two, std::cmp::min(n1, n2), std::cmp::max(n1, n2))
+            }
+            (Some(n), _) | (_, Some(n)) => (ActualImplExpectedLifetimeKind::Any, n, 0),
+            (None, None) => {
+                if let Some(n) = expected_has_vid {
+                    (ActualImplExpectedLifetimeKind::Some, n, 0)
+                } else {
+                    (ActualImplExpectedLifetimeKind::Nothing, 0, 0)
+                }
+            }
+        };
+
+        let note_1 = ActualImplExplNotes::new_expected(
+            kind,
+            lt_kind,
+            leading_ellipsis,
+            ty_or_sig,
+            trait_path,
+            lifetime_1,
+            lifetime_2,
+        );
 
         let mut actual_trait_ref = highlight_trait_ref(actual_trait_ref);
         actual_trait_ref.highlight.maybe_highlighting_region(vid, actual_has_vid);
-        err.note(&{
-            let passive_voice = match actual_has_vid {
-                Some(_) => any_self_ty_has_vid,
-                None => true,
-            };
 
-            let mut note = if same_self_type {
+        let passive_voice = match actual_has_vid {
-                format!(
+            Some(_) => any_self_ty_has_vid,
-                    "...but it actually implements `{}`",
+            None => true,
-                    actual_trait_ref.map(|tr| tr.print_only_trait_path()),
+        };
-                )
-            } else if passive_voice {
-                format!(
-                    "...but `{}` is actually implemented for the type `{}`",
-                    actual_trait_ref.map(|tr| tr.print_only_trait_path()),
-                    actual_trait_ref.map(|tr| tr.self_ty()),
-                )
-            } else {
-                format!(
-                    "...but `{}` actually implements `{}`",
-                    actual_trait_ref.map(|tr| tr.self_ty()),
-                    actual_trait_ref.map(|tr| tr.print_only_trait_path()),
-                )
-            };
 
-            if let Some(n) = actual_has_vid {
+        let trait_path = actual_trait_ref.map(|tr| tr.print_only_trait_path());
-                let _ = write!(note, ", for some specific lifetime `'{}`", n);
+        let ty = actual_trait_ref.map(|tr| tr.self_ty()).to_string();
+        let has_lifetime = actual_has_vid.is_some();
+        let lifetime = actual_has_vid.unwrap_or_default();
+
+        let note_2 = if same_self_type {
+            ActualImplExplNotes::ButActuallyImplementsTrait { trait_path, has_lifetime, lifetime }
+        } else if passive_voice {
+            ActualImplExplNotes::ButActuallyImplementedForTy {
+                trait_path,
+                ty,
+                has_lifetime,
+                lifetime,
             }
+        } else {
+            ActualImplExplNotes::ButActuallyTyImplements { trait_path, ty, has_lifetime, lifetime }
+        };
 
-            note
+        vec![note_1, note_2]
-        });
     }
 }

compiler/rustc_infer/src/infer/error_reporting/nice_region_error/static_impl_trait.rs

@@ -1,11 +1,15 @@
 //! Error Reporting for static impl Traits.
 
+use crate::errors::{
+    ButCallingIntroduces, ButNeedsToSatisfy, DynTraitConstraintSuggestion, MoreTargeted,
+    ReqIntroducedLocations,
+};
 use crate::infer::error_reporting::nice_region_error::NiceRegionError;
 use crate::infer::lexical_region_resolve::RegionResolutionError;
 use crate::infer::{SubregionOrigin, TypeTrace};
 use crate::traits::{ObligationCauseCode, UnifyReceiverContext};
 use rustc_data_structures::fx::FxIndexSet;
-use rustc_errors::{struct_span_err, Applicability, Diagnostic, ErrorGuaranteed, MultiSpan};
+use rustc_errors::{AddToDiagnostic, Applicability, Diagnostic, ErrorGuaranteed, MultiSpan};
 use rustc_hir::def_id::DefId;
 use rustc_hir::intravisit::{walk_ty, Visitor};
 use rustc_hir::{
@@ -53,46 +57,32 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                     }
 
                     let param = self.find_param_with_region(*sup_r, *sub_r)?;
-                    let lifetime = if sup_r.has_name() {
+                    let simple_ident = param.param.pat.simple_ident();
-                        format!("lifetime `{}`", sup_r)
+
-                    } else {
+                    let (has_impl_path, impl_path) = match ctxt.assoc_item.container {
-                        "an anonymous lifetime `'_`".to_string()
+                        AssocItemContainer::TraitContainer => {
+                            let id = ctxt.assoc_item.container_id(tcx);
+                            (true, tcx.def_path_str(id))
+                        }
+                        AssocItemContainer::ImplContainer => (false, String::new()),
                     };
-                    let mut err = struct_span_err!(
+
-                        tcx.sess,
+                    let mut err = self.tcx().sess.create_err(ButCallingIntroduces {
-                        cause.span,
+                        param_ty_span: param.param_ty_span,
-                        E0772,
+                        cause_span: cause.span,
-                        "{} has {} but calling `{}` introduces an implicit `'static` lifetime \
+                        has_param_name: simple_ident.is_some(),
-                         requirement",
+                        param_name: simple_ident.map(|x| x.to_string()).unwrap_or_default(),
-                        param
+                        has_lifetime: sup_r.has_name(),
-                            .param
+                        lifetime: sup_r.to_string(),
-                            .pat
+                        assoc_item: ctxt.assoc_item.name,
-                            .simple_ident()
+                        has_impl_path,
-                            .map(|s| format!("`{}`", s))
+                        impl_path,
-                            .unwrap_or_else(|| "`fn` parameter".to_string()),
+                    });
-                        lifetime,
-                        ctxt.assoc_item.name,
-                    );
-                    err.span_label(param.param_ty_span, &format!("this data with {}...", lifetime));
-                    err.span_label(
-                        cause.span,
-                        &format!(
-                            "...is used and required to live as long as `'static` here \
-                             because of an implicit lifetime bound on the {}",
-                            match ctxt.assoc_item.container {
-                                AssocItemContainer::TraitContainer => {
-                                    let id = ctxt.assoc_item.container_id(tcx);
-                                    format!("`impl` of `{}`", tcx.def_path_str(id))
-                                }
-                                AssocItemContainer::ImplContainer => "inherent `impl`".to_string(),
-                            },
-                        ),
-                    );
                     if self.find_impl_on_dyn_trait(&mut err, param.param_ty, &ctxt) {
                         let reported = err.emit();
                         return Some(reported);
                     } else {
-                        err.cancel();
+                        err.cancel()
                     }
                 }
                 return None;
@@ -108,25 +98,7 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
         let sp = var_origin.span();
         let return_sp = sub_origin.span();
         let param = self.find_param_with_region(*sup_r, *sub_r)?;
-        let (lifetime_name, lifetime) = if sup_r.has_name() {
+        let lifetime_name = if sup_r.has_name() { sup_r.to_string() } else { "'_".to_owned() };
-            (sup_r.to_string(), format!("lifetime `{}`", sup_r))
-        } else {
-            ("'_".to_owned(), "an anonymous lifetime `'_`".to_string())
-        };
-        let param_name = param
-            .param
-            .pat
-            .simple_ident()
-            .map(|s| format!("`{}`", s))
-            .unwrap_or_else(|| "`fn` parameter".to_string());
-        let mut err = struct_span_err!(
-            tcx.sess,
-            sp,
-            E0759,
-            "{} has {} but it needs to satisfy a `'static` lifetime requirement",
-            param_name,
-            lifetime,
-        );
 
         let (mention_influencer, influencer_point) =
             if sup_origin.span().overlaps(param.param_ty_span) {
@@ -145,7 +117,6 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
             } else {
                 (!sup_origin.span().overlaps(return_sp), param.param_ty_span)
             };
-        err.span_label(influencer_point, &format!("this data with {}...", lifetime));
 
         debug!("try_report_static_impl_trait: param_info={:?}", param);
 
@@ -159,31 +130,19 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
         spans.dedup_by_key(|span| (span.lo(), span.hi()));
 
         // We try to make the output have fewer overlapping spans if possible.
-        let require_msg = if spans.is_empty() {
-            "...is used and required to live as long as `'static` here"
-        } else {
-            "...and is required to live as long as `'static` here"
-        };
         let require_span =
             if sup_origin.span().overlaps(return_sp) { sup_origin.span() } else { return_sp };
 
-        for span in &spans {
+        let spans_empty = spans.is_empty();
-            err.span_label(*span, "...is used here...");
+        let require_as_note = spans.iter().any(|sp| sp.overlaps(return_sp) || *sp > return_sp);
-        }
+        let bound = if let SubregionOrigin::RelateParamBound(_, _, Some(bound)) = sub_origin {
-
+            Some(*bound)
-        if spans.iter().any(|sp| sp.overlaps(return_sp) || *sp > return_sp) {
-            // If any of the "captured here" labels appears on the same line or after
-            // `require_span`, we put it on a note to ensure the text flows by appearing
-            // always at the end.
-            err.span_note(require_span, require_msg);
         } else {
-            // We don't need a note, it's already at the end, it can be shown as a `span_label`.
+            None
-            err.span_label(require_span, require_msg);
+        };
-        }
+
+        let mut subdiag = None;
 
-        if let SubregionOrigin::RelateParamBound(_, _, Some(bound)) = sub_origin {
-            err.span_note(*bound, "`'static` lifetime requirement introduced by this bound");
-        }
         if let SubregionOrigin::Subtype(box TypeTrace { cause, .. }) = sub_origin {
             if let ObligationCauseCode::ReturnValue(hir_id)
             | ObligationCauseCode::BlockTailExpression(hir_id) = cause.code()
@@ -191,33 +150,50 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                 let parent_id = tcx.hir().get_parent_item(*hir_id);
                 if let Some(fn_decl) = tcx.hir().fn_decl_by_hir_id(parent_id.into()) {
                     let mut span: MultiSpan = fn_decl.output.span().into();
+                    let mut spans = Vec::new();
                     let mut add_label = true;
                     if let hir::FnRetTy::Return(ty) = fn_decl.output {
                         let mut v = StaticLifetimeVisitor(vec![], tcx.hir());
                         v.visit_ty(ty);
                         if !v.0.is_empty() {
                             span = v.0.clone().into();
-                            for sp in v.0 {
+                            spans = v.0;
-                                span.push_span_label(sp, "`'static` requirement introduced here");
-                            }
                             add_label = false;
                         }
                     }
-                    if add_label {
+                    let fn_decl_span = fn_decl.output.span();
-                        span.push_span_label(
+
-                            fn_decl.output.span(),
+                    subdiag = Some(ReqIntroducedLocations {
-                            "requirement introduced by this return type",
-                        );
-                    }
-                    span.push_span_label(cause.span, "because of this returned expression");
-                    err.span_note(
                         span,
-                        "`'static` lifetime requirement introduced by the return type",
+                        spans,
-                    );
+                        fn_decl_span,
+                        cause_span: cause.span,
+                        add_label,
+                    });
                 }
             }
         }
 
+        let diag = ButNeedsToSatisfy {
+            sp,
+            influencer_point,
+            spans: spans.clone(),
+            // If any of the "captured here" labels appears on the same line or after
+            // `require_span`, we put it on a note to ensure the text flows by appearing
+            // always at the end.
+            require_span_as_note: require_as_note.then_some(require_span),
+            // We don't need a note, it's already at the end, it can be shown as a `span_label`.
+            require_span_as_label: (!require_as_note).then_some(require_span),
+            req_introduces_loc: subdiag,
+
+            has_lifetime: sup_r.has_name(),
+            lifetime: sup_r.to_string(),
+            spans_empty,
+            bound,
+        };
+
+        let mut err = self.tcx().sess.create_err(diag);
+
         let fn_returns = tcx.return_type_impl_or_dyn_traits(anon_reg_sup.def_id);
 
         let mut override_error_code = None;
@@ -251,12 +227,8 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
         }
         if let (Some(ident), true) = (override_error_code, fn_returns.is_empty()) {
             // Provide a more targeted error code and description.
-            err.code(rustc_errors::error_code!(E0772));
+            let retarget_subdiag = MoreTargeted { ident };
-            err.set_primary_message(&format!(
+            retarget_subdiag.add_to_diagnostic(&mut err);
-                "{} has {} but calling `{}` introduces an implicit `'static` lifetime \
-                requirement",
-                param_name, lifetime, ident,
-            ));
         }
 
         let arg = match param.param.pat.simple_ident() {
@@ -551,21 +523,9 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
             let mut traits = vec![];
             let mut hir_v = HirTraitObjectVisitor(&mut traits, *found_did);
             hir_v.visit_ty(&self_ty);
-            for span in &traits {
+            for &span in &traits {
-                let mut multi_span: MultiSpan = vec![*span].into();
+                let subdiag = DynTraitConstraintSuggestion { span, ident };
-                multi_span
+                subdiag.add_to_diagnostic(err);
-                    .push_span_label(*span, "this has an implicit `'static` lifetime requirement");
-                multi_span.push_span_label(
-                    ident.span,
-                    "calling this method introduces the `impl`'s 'static` requirement",
-                );
-                err.span_note(multi_span, "the used `impl` has a `'static` requirement");
-                err.span_suggestion_verbose(
-                    span.shrink_to_hi(),
-                    "consider relaxing the implicit `'static` requirement",
-                    " + '_",
-                    Applicability::MaybeIncorrect,
-                );
                 suggested = true;
             }
         }

compiler/rustc_infer/src/infer/error_reporting/nice_region_error/trait_impl_difference.rs

@@ -1,10 +1,11 @@
 //! Error Reporting for `impl` items that do not match the obligations from their `trait`.
 
+use crate::errors::{ConsiderBorrowingParamHelp, RelationshipHelp, TraitImplDiff};
 use crate::infer::error_reporting::nice_region_error::NiceRegionError;
 use crate::infer::lexical_region_resolve::RegionResolutionError;
 use crate::infer::Subtype;
 use crate::traits::ObligationCauseCode::CompareImplItemObligation;
-use rustc_errors::{ErrorGuaranteed, MultiSpan};
+use rustc_errors::ErrorGuaranteed;
 use rustc_hir as hir;
 use rustc_hir::def::Res;
 use rustc_hir::def_id::DefId;
@@ -51,10 +52,6 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
         trait_def_id: DefId,
     ) -> ErrorGuaranteed {
         let trait_sp = self.tcx().def_span(trait_def_id);
-        let mut err = self
-            .tcx()
-            .sess
-            .struct_span_err(sp, "`impl` item signature doesn't match `trait` item signature");
 
         // Mark all unnamed regions in the type with a number.
         // This diagnostic is called in response to lifetime errors, so be informative.
@@ -91,9 +88,6 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
         let found =
             self.cx.extract_inference_diagnostics_data(found.into(), Some(found_highlight)).name;
 
-        err.span_label(sp, &format!("found `{}`", found));
-        err.span_label(trait_sp, &format!("expected `{}`", expected));
-
         // Get the span of all the used type parameters in the method.
         let assoc_item = self.tcx().associated_item(trait_def_id);
         let mut visitor = TypeParamSpanVisitor { tcx: self.tcx(), types: vec![] };
@@ -110,26 +104,18 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
             }
             _ => {}
         }
-        let mut type_param_span: MultiSpan = visitor.types.to_vec().into();
-        for &span in &visitor.types {
-            type_param_span
-                .push_span_label(span, "consider borrowing this type parameter in the trait");
-        }
 
-        err.note(&format!("expected `{}`\n   found `{}`", expected, found));
+        let diag = TraitImplDiff {
+            sp,
+            trait_sp,
+            note: (),
+            param_help: ConsiderBorrowingParamHelp { spans: visitor.types.to_vec() },
+            rel_help: visitor.types.is_empty().then_some(RelationshipHelp),
+            expected,
+            found,
+        };
 
-        err.span_help(
+        self.tcx().sess.emit_err(diag)
-            type_param_span,
-            "the lifetime requirements from the `impl` do not correspond to the requirements in \
-             the `trait`",
-        );
-        if visitor.types.is_empty() {
-            err.help(
-                "verify the lifetime relationships in the `trait` and `impl` between the `self` \
-                 argument, the other inputs and its output",
-            );
-        }
-        err.emit()
     }
 }