Auto merge of #14326 - iDawer:refactor, r=Veykril

internal: Rename `hir::diagnostics::MissingMatchArms.match_expr` field

`hir::diagnostics::MissingMatchArms.match_expr` had confusing name: it is pointing to scrutinee expression. Renamed to `scrutinee_expr` and used better fitting type for it.

Also small refactorings/cleanup.

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

@@ -84,7 +84,7 @@ impl ExprValidator {
 
             match expr {
                 Expr::Match { expr, arms } => {
-                    self.validate_match(id, *expr, arms, db, self.infer.clone());
+                    self.validate_match(id, *expr, arms, db);
                 }
                 Expr::Call { .. } | Expr::MethodCall { .. } => {
                     self.validate_call(db, id, expr, &mut filter_map_next_checker);
@@ -147,16 +147,15 @@ impl ExprValidator {
 
     fn validate_match(
         &mut self,
-        id: ExprId,
         match_expr: ExprId,
+        scrutinee_expr: ExprId,
         arms: &[MatchArm],
         db: &dyn HirDatabase,
-        infer: Arc<InferenceResult>,
     ) {
         let body = db.body(self.owner);
 
-        let match_expr_ty = &infer[match_expr];
-        if match_expr_ty.is_unknown() {
+        let scrut_ty = &self.infer[scrutinee_expr];
+        if scrut_ty.is_unknown() {
             return;
         }
 
@@ -166,23 +165,23 @@ impl ExprValidator {
         let mut m_arms = Vec::with_capacity(arms.len());
         let mut has_lowering_errors = false;
         for arm in arms {
-            if let Some(pat_ty) = infer.type_of_pat.get(arm.pat) {
+            if let Some(pat_ty) = self.infer.type_of_pat.get(arm.pat) {
                 // We only include patterns whose type matches the type
-                // of the match expression. If we had an InvalidMatchArmPattern
+                // of the scrutinee expression. If we had an InvalidMatchArmPattern
                 // diagnostic or similar we could raise that in an else
                 // block here.
                 //
                 // When comparing the types, we also have to consider that rustc
-                // will automatically de-reference the match expression type if
+                // will automatically de-reference the scrutinee expression type if
                 // necessary.
                 //
                 // FIXME we should use the type checker for this.
-                if (pat_ty == match_expr_ty
-                    || match_expr_ty
+                if (pat_ty == scrut_ty
+                    || scrut_ty
                         .as_reference()
                         .map(|(match_expr_ty, ..)| match_expr_ty == pat_ty)
                         .unwrap_or(false))
-                    && types_of_subpatterns_do_match(arm.pat, &body, &infer)
+                    && types_of_subpatterns_do_match(arm.pat, &body, &self.infer)
                 {
                     // If we had a NotUsefulMatchArm diagnostic, we could
                     // check the usefulness of each pattern as we added it
@@ -206,7 +205,7 @@ impl ExprValidator {
             return;
         }
 
-        let report = compute_match_usefulness(&cx, &m_arms, match_expr_ty);
+        let report = compute_match_usefulness(&cx, &m_arms, scrut_ty);
 
         // FIXME Report unreacheble arms
         // https://github.com/rust-lang/rust/blob/f31622a50/compiler/rustc_mir_build/src/thir/pattern/check_match.rs#L200
@@ -214,8 +213,8 @@ impl ExprValidator {
         let witnesses = report.non_exhaustiveness_witnesses;
         if !witnesses.is_empty() {
             self.diagnostics.push(BodyValidationDiagnostic::MissingMatchArms {
-                match_expr: id,
-                uncovered_patterns: missing_match_arms(&cx, match_expr_ty, witnesses, arms),
+                match_expr,
+                uncovered_patterns: missing_match_arms(&cx, scrut_ty, witnesses, arms),
             });
         }
     }
@@ -379,7 +378,7 @@ fn missing_match_arms<'p>(
     arms: &[MatchArm],
 ) -> String {
     struct DisplayWitness<'a, 'p>(&'a DeconstructedPat<'p>, &'a MatchCheckCtx<'a, 'p>);
-    impl<'a, 'p> fmt::Display for DisplayWitness<'a, '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);

crates/hir/src/diagnostics.rs

@@ -199,8 +199,7 @@ pub struct MismatchedArgCount {
 
 #[derive(Debug)]
 pub struct MissingMatchArms {
-    pub file: HirFileId,
-    pub match_expr: AstPtr<ast::Expr>,
+    pub scrutinee_expr: InFile<AstPtr<ast::Expr>>,
     pub uncovered_patterns: String,
 }
 

crates/hir/src/lib.rs

@@ -1628,11 +1628,13 @@ impl DefWithBody {
                             if let ast::Expr::MatchExpr(match_expr) =
                                 &source_ptr.value.to_node(&root)
                             {
-                                if let Some(match_expr) = match_expr.expr() {
+                                if let Some(scrut_expr) = match_expr.expr() {
                                     acc.push(
                                         MissingMatchArms {
-                                            file: source_ptr.file_id,
-                                            match_expr: AstPtr::new(&match_expr),
+                                            scrutinee_expr: InFile::new(
+                                                source_ptr.file_id,
+                                                AstPtr::new(&scrut_expr),
+                                            ),
                                             uncovered_patterns,
                                         }
                                         .into(),

crates/ide-diagnostics/src/handlers/missing_match_arms.rs

@@ -1,5 +1,3 @@
-use hir::InFile;
-
 use crate::{Diagnostic, DiagnosticsContext};
 
 // Diagnostic: missing-match-arm
@@ -12,7 +10,7 @@ pub(crate) fn missing_match_arms(
     Diagnostic::new(
         "missing-match-arm",
         format!("missing match arm: {}", d.uncovered_patterns),
-        ctx.sema.diagnostics_display_range(InFile::new(d.file, d.match_expr.clone().into())).range,
+        ctx.sema.diagnostics_display_range(d.scrutinee_expr.clone().map(Into::into)).range,
     )
 }