Move rustc-specific entrypoint to the `rustc` module

compiler/rustc_mir_build/src/thir/pattern/check_match.rs

@@ -391,12 +391,16 @@ impl<'p, 'tcx> MatchVisitor<'p, 'tcx> {
     ) -> Result<UsefulnessReport<'p, 'tcx>, ErrorGuaranteed> {
         let pattern_complexity_limit =
             get_limit_size(cx.tcx.hir().krate_attrs(), cx.tcx.sess, sym::pattern_complexity);
-        let report =
-            rustc_pattern_analysis::analyze_match(&cx, &arms, scrut_ty, pattern_complexity_limit)
-                .map_err(|err| {
-                self.error = Err(err);
-                err
-            })?;
+        let report = rustc_pattern_analysis::rustc::analyze_match(
+            &cx,
+            &arms,
+            scrut_ty,
+            pattern_complexity_limit,
+        )
+        .map_err(|err| {
+            self.error = Err(err);
+            err
+        })?;
 
         // Warn unreachable subpatterns.
         for (arm, is_useful) in report.arm_usefulness.iter() {

compiler/rustc_pattern_analysis/src/lib.rs

@@ -1,4 +1,6 @@
-//! Analysis of patterns, notably match exhaustiveness checking.
+//! Analysis of patterns, notably match exhaustiveness checking. The main entrypoint for this crate
+//! is [`usefulness::compute_match_usefulness`]. For rustc-specific types and entrypoints, see the
+//! [`rustc`] module.
 
 // tidy-alphabetical-start
 #![allow(rustc::diagnostic_outside_of_impl)]
@@ -23,14 +25,8 @@ use std::fmt;
 
 pub use rustc_index::{Idx, IndexVec}; // re-exported to avoid rustc_index version issues
 
-#[cfg(feature = "rustc")]
-use rustc_middle::ty::Ty;
-#[cfg(feature = "rustc")]
-use rustc_span::ErrorGuaranteed;
-
 use crate::constructor::{Constructor, ConstructorSet, IntRange};
 use crate::pat::DeconstructedPat;
-use crate::pat_column::PatternColumn;
 
 pub trait Captures<'a> {}
 impl<'a, T: ?Sized> Captures<'a> for T {}
@@ -128,30 +124,3 @@ impl<'p, Cx: PatCx> Clone for MatchArm<'p, Cx> {
 }
 
 impl<'p, Cx: PatCx> Copy for MatchArm<'p, Cx> {}
-
-/// The entrypoint for this crate. Computes whether a match is exhaustive and which of its arms are
-/// useful, and runs some lints.
-#[cfg(feature = "rustc")]
-pub fn analyze_match<'p, 'tcx>(
-    tycx: &rustc::RustcPatCtxt<'p, 'tcx>,
-    arms: &[rustc::MatchArm<'p, 'tcx>],
-    scrut_ty: Ty<'tcx>,
-    pattern_complexity_limit: Option<usize>,
-) -> Result<rustc::UsefulnessReport<'p, 'tcx>, ErrorGuaranteed> {
-    use lints::lint_nonexhaustive_missing_variants;
-    use usefulness::{compute_match_usefulness, PlaceValidity};
-
-    let scrut_ty = tycx.reveal_opaque_ty(scrut_ty);
-    let scrut_validity = PlaceValidity::from_bool(tycx.known_valid_scrutinee);
-    let report =
-        compute_match_usefulness(tycx, arms, scrut_ty, scrut_validity, pattern_complexity_limit)?;
-
-    // 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 tycx.refutable && report.non_exhaustiveness_witnesses.is_empty() {
-        let pat_column = PatternColumn::new(arms);
-        lint_nonexhaustive_missing_variants(tycx, arms, &pat_column, scrut_ty)?;
-    }
-
-    Ok(report)
-}

compiler/rustc_pattern_analysis/src/rustc.rs

@@ -20,6 +20,9 @@ use rustc_target::abi::{FieldIdx, Integer, VariantIdx, FIRST_VARIANT};
 use crate::constructor::{
     IntRange, MaybeInfiniteInt, OpaqueId, RangeEnd, Slice, SliceKind, VariantVisibility,
 };
+use crate::lints::lint_nonexhaustive_missing_variants;
+use crate::pat_column::PatternColumn;
+use crate::usefulness::{compute_match_usefulness, PlaceValidity};
 use crate::{errors, Captures, PatCx, PrivateUninhabitedField};
 
 use crate::constructor::Constructor::*;
@@ -1058,3 +1061,26 @@ fn expand_or_pat<'p, 'tcx>(pat: &'p Pat<'tcx>) -> Vec<&'p Pat<'tcx>> {
     expand(pat, &mut pats);
     pats
 }
+
+/// 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>(
+    tycx: &RustcPatCtxt<'p, 'tcx>,
+    arms: &[MatchArm<'p, 'tcx>],
+    scrut_ty: Ty<'tcx>,
+    pattern_complexity_limit: Option<usize>,
+) -> Result<UsefulnessReport<'p, 'tcx>, ErrorGuaranteed> {
+    let scrut_ty = tycx.reveal_opaque_ty(scrut_ty);
+    let scrut_validity = PlaceValidity::from_bool(tycx.known_valid_scrutinee);
+    let report =
+        compute_match_usefulness(tycx, arms, scrut_ty, scrut_validity, pattern_complexity_limit)?;
+
+    // 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 tycx.refutable && report.non_exhaustiveness_witnesses.is_empty() {
+        let pat_column = PatternColumn::new(arms);
+        lint_nonexhaustive_missing_variants(tycx, arms, &pat_column, scrut_ty)?;
+    }
+
+    Ok(report)
+}