Move lints to their own module

compiler/rustc_pattern_analysis/src/lib.rs

@@ -3,6 +3,7 @@
 pub mod constructor;
 pub mod cx;
 pub mod errors;
+pub(crate) mod lints;
 pub mod pat;
 pub mod usefulness;
 
@@ -12,3 +13,44 @@ extern crate tracing;
 extern crate rustc_middle;
 
 rustc_fluent_macro::fluent_messages! { "../messages.ftl" }
+
+use lints::PatternColumn;
+use rustc_hir::HirId;
+use rustc_middle::ty::Ty;
+use usefulness::{compute_match_usefulness, UsefulnessReport};
+
+use crate::cx::MatchCheckCtxt;
+use crate::lints::{lint_nonexhaustive_missing_variants, lint_overlapping_range_endpoints};
+use crate::pat::DeconstructedPat;
+
+/// The arm of a match expression.
+#[derive(Clone, Copy, Debug)]
+pub struct MatchArm<'p, 'tcx> {
+    /// The pattern must have been lowered through `check_match::MatchVisitor::lower_pattern`.
+    pub pat: &'p DeconstructedPat<'p, 'tcx>,
+    pub hir_id: HirId,
+    pub has_guard: bool,
+}
+
+/// The entrypoint for this crate. Computes whether a match is exhaustive and which of its arms are
+/// useful, and runs some lints.
+pub fn analyze_match<'p, 'tcx>(
+    cx: &MatchCheckCtxt<'p, 'tcx>,
+    arms: &[MatchArm<'p, 'tcx>],
+    scrut_ty: Ty<'tcx>,
+) -> UsefulnessReport<'p, 'tcx> {
+    let pat_column = PatternColumn::new(arms);
+
+    let report = compute_match_usefulness(cx, arms, scrut_ty);
+
+    // Lint on ranges that overlap on their endpoints, which is likely a mistake.
+    lint_overlapping_range_endpoints(cx, &pat_column);
+
+    // Run the non_exhaustive_omitted_patterns lint. Only run on refutable patterns to avoid hitting
+    // `if let`s. Only run if the match is exhaustive otherwise the error is redundant.
+    if cx.refutable && report.non_exhaustiveness_witnesses.is_empty() {
+        lint_nonexhaustive_missing_variants(cx, arms, &pat_column, scrut_ty)
+    }
+
+    report
+}