Auto merge of #16420 - Nadrieril:use-upstream-pattern-analysis, r=Veykril

Use upstream exhaustiveness checker!

Because it has been librarified!

The extra `Apache-2.0 WITH LLVM-exception` license is for `rustc_apfloat`. Also this duplicates `rustc_index` because the other upstream deps are still on an earlier version. They should be bumpable now though. Good thing is that we don't need this new crate to be synchronized with the others, which will make our lives easier.

Author: bors

Cargo.lock

@@ -83,6 +83,7 @@ ra-ap-rustc_lexer = { version = "0.21.0", default-features = false }
 ra-ap-rustc_parse_format = { version = "0.21.0", default-features = false }
 ra-ap-rustc_index = { version = "0.21.0", default-features = false }
 ra-ap-rustc_abi = { version = "0.21.0", default-features = false }
+ra-ap-rustc_pattern_analysis = { version = "0.33.0", default-features = false }
 
 # local crates that aren't published to crates.io. These should not have versions.
 sourcegen = { path = "./crates/sourcegen" }

Cargo.toml

@@ -939,6 +939,15 @@ impl From<AssocItemId> for AttrDefId {
         }
     }
 }
+impl From<VariantId> for AttrDefId {
+    fn from(vid: VariantId) -> Self {
+        match vid {
+            VariantId::EnumVariantId(id) => id.into(),
+            VariantId::StructId(id) => id.into(),
+            VariantId::UnionId(id) => id.into(),
+        }
+    }
+}
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub enum VariantId {

crates/hir-def/src/lib.rs

@@ -36,6 +36,7 @@ indexmap.workspace = true
 
 ra-ap-rustc_abi.workspace = true
 ra-ap-rustc_index.workspace = true
+ra-ap-rustc_pattern_analysis.workspace = true
 
 
 # local deps

crates/hir-ty/Cargo.toml

@@ -11,15 +11,15 @@ use hir_def::{ItemContainerId, Lookup};
 use hir_expand::name;
 use itertools::Itertools;
 use rustc_hash::FxHashSet;
+use rustc_pattern_analysis::usefulness::{compute_match_usefulness, ValidityConstraint};
 use triomphe::Arc;
 use typed_arena::Arena;
 
 use crate::{
     db::HirDatabase,
     diagnostics::match_check::{
         self,
-        deconstruct_pat::DeconstructedPat,
-        usefulness::{compute_match_usefulness, MatchCheckCtx},
+        pat_analysis::{self, DeconstructedPat, MatchCheckCtx, WitnessPat},
     },
     display::HirDisplay,
     InferenceResult, Ty, TyExt,
@@ -152,7 +152,14 @@ impl ExprValidator {
         }
 
         let pattern_arena = Arena::new();
-        let cx = MatchCheckCtx::new(self.owner.module(db.upcast()), self.owner, db, &pattern_arena);
+        let ty_arena = Arena::new();
+        let cx = MatchCheckCtx::new(
+            self.owner.module(db.upcast()),
+            self.owner,
+            db,
+            &pattern_arena,
+            &ty_arena,
+        );
 
         let mut m_arms = Vec::with_capacity(arms.len());
         let mut has_lowering_errors = false;
@@ -178,9 +185,10 @@ impl ExprValidator {
                     // If we had a NotUsefulMatchArm diagnostic, we could
                     // check the usefulness of each pattern as we added it
                     // to the matrix here.
-                    let m_arm = match_check::MatchArm {
+                    let m_arm = pat_analysis::MatchArm {
                         pat: self.lower_pattern(&cx, arm.pat, db, &body, &mut has_lowering_errors),
                         has_guard: arm.guard.is_some(),
+                        arm_data: (),
                     };
                     m_arms.push(m_arm);
                     if !has_lowering_errors {
@@ -197,7 +205,15 @@ impl ExprValidator {
             return;
         }
 
-        let report = compute_match_usefulness(&cx, &m_arms, scrut_ty);
+        let report = match compute_match_usefulness(
+            rustc_pattern_analysis::MatchCtxt { tycx: &cx },
+            m_arms.as_slice(),
+            scrut_ty.clone(),
+            ValidityConstraint::ValidOnly,
+        ) {
+            Ok(report) => report,
+            Err(void) => match void {},
+        };
 
         // FIXME Report unreachable arms
         // https://github.com/rust-lang/rust/blob/f31622a50/compiler/rustc_mir_build/src/thir/pattern/check_match.rs#L200
@@ -213,15 +229,15 @@ impl ExprValidator {
 
     fn lower_pattern<'p>(
         &self,
-        cx: &MatchCheckCtx<'_, 'p>,
+        cx: &MatchCheckCtx<'p>,
         pat: PatId,
         db: &dyn HirDatabase,
         body: &Body,
         have_errors: &mut bool,
     ) -> &'p DeconstructedPat<'p> {
         let mut patcx = match_check::PatCtxt::new(db, &self.infer, body);
         let pattern = patcx.lower_pattern(pat);
-        let pattern = cx.pattern_arena.alloc(DeconstructedPat::from_pat(cx, &pattern));
+        let pattern = cx.pattern_arena.alloc(cx.lower_pat(&pattern));
         if !patcx.errors.is_empty() {
             *have_errors = true;
         }
@@ -364,16 +380,16 @@ fn types_of_subpatterns_do_match(pat: PatId, body: &Body, infer: &InferenceResul
 }
 
 fn missing_match_arms<'p>(
-    cx: &MatchCheckCtx<'_, 'p>,
+    cx: &MatchCheckCtx<'p>,
     scrut_ty: &Ty,
-    witnesses: Vec<DeconstructedPat<'p>>,
+    witnesses: Vec<WitnessPat<'p>>,
     arms: &[MatchArm],
 ) -> String {
-    struct DisplayWitness<'a, 'p>(&'a DeconstructedPat<'p>, &'a MatchCheckCtx<'a, 'p>);
+    struct DisplayWitness<'a, 'p>(&'a WitnessPat<'p>, &'a MatchCheckCtx<'p>);
     impl fmt::Display for DisplayWitness<'_, '_> {
         fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
             let DisplayWitness(witness, cx) = *self;
-            let pat = witness.to_pat(cx);
+            let pat = cx.hoist_witness_pat(witness);
             write!(f, "{}", pat.display(cx.db))
         }
     }

crates/hir-ty/src/diagnostics/expr.rs

@@ -7,8 +7,7 @@
 
 mod pat_util;
 
-pub(crate) mod deconstruct_pat;
-pub(crate) mod usefulness;
+pub(crate) mod pat_analysis;
 
 use chalk_ir::Mutability;
 use hir_def::{
@@ -27,8 +26,6 @@ use crate::{
 
 use self::pat_util::EnumerateAndAdjustIterator;
 
-pub(crate) use self::usefulness::MatchArm;
-
 #[derive(Clone, Debug)]
 pub(crate) enum PatternError {
     Unimplemented,