compiler/rustc_lint/src/expect.rs

   1 use crate::builtin;
   2 use rustc_hir::HirId;
   3 use rustc_middle::ty::query::Providers;
   4 use rustc_middle::{lint::LintExpectation, ty::TyCtxt};
   5 use rustc_session::lint::LintExpectationId;
   6 use rustc_span::symbol::sym;
   7 use rustc_span::Symbol;
   8
   9 pub(crate) fn provide(providers: &mut Providers) {
  10     *providers = Providers { check_expectations, ..*providers };
  11 }
  12
  13 fn check_expectations(tcx: TyCtxt<'_>, tool_filter: Option<Symbol>) {
  14     if !tcx.sess.features_untracked().enabled(sym::lint_reasons) {
  15         return;
  16     }
  17
  18     let fulfilled_expectations = tcx.sess.diagnostic().steal_fulfilled_expectation_ids();
  19     let lint_expectations = &tcx.lint_levels(()).lint_expectations;
  20
  21     for (id, expectation) in lint_expectations {
  22         // This check will always be true, since `lint_expectations` only
  23         // holds stable ids
  24         if let LintExpectationId::Stable { hir_id, .. } = id {
  25             if !fulfilled_expectations.contains(&id)
  26                 && tool_filter.map_or(true, |filter| expectation.lint_tool == Some(filter))
  27             {
  28                 emit_unfulfilled_expectation_lint(tcx, *hir_id, expectation);
  29             }
  30         } else {
  31             unreachable!("at this stage all `LintExpectationId`s are stable");
  32         }
  33     }
  34 }
  35
  36 fn emit_unfulfilled_expectation_lint(
  37     tcx: TyCtxt<'_>,
  38     hir_id: HirId,
  39     expectation: &LintExpectation,
  40 ) {
  41     tcx.struct_span_lint_hir(
  42         builtin::UNFULFILLED_LINT_EXPECTATIONS,
  43         hir_id,
  44         expectation.emission_span,
  45         |diag| {
  46             let mut diag = diag.build("this lint expectation is unfulfilled");
  47             if let Some(rationale) = expectation.reason {
  48                 diag.note(rationale.as_str());
  49             }
  50
  51             if expectation.is_unfulfilled_lint_expectations {
  52                 diag.note("the `unfulfilled_lint_expectations` lint can't be expected and will always produce this message");
  53             }
  54
  55             diag.emit();
  56         },
  57     );
  58 }