Merge #3074

3074: Or patterns r=matthewjasper a=matthewjasper

Works towards #2458

Co-authored-by: Matthew Jasper <mjjasper1@gmail.com>

Author: bors[bot]

crates/ra_assists/src/handlers/fill_match_arms.rs

@@ -75,10 +75,10 @@ pub(crate) fn fill_match_arms(ctx: AssistCtx) -> Option<Assist> {
 }
 
 fn is_trivial(arm: &ast::MatchArm) -> bool {
-    arm.pats().any(|pat| match pat {
-        ast::Pat::PlaceholderPat(..) => true,
+    match arm.pat() {
+        Some(ast::Pat::PlaceholderPat(..)) => true,
         _ => false,
-    })
+    }
 }
 
 fn resolve_enum_def(

crates/ra_assists/src/handlers/merge_match_arms.rs

@@ -75,7 +75,7 @@ pub(crate) fn merge_match_arms(ctx: AssistCtx) -> Option<Assist> {
         } else {
             arms_to_merge
                 .iter()
-                .flat_map(ast::MatchArm::pats)
+                .filter_map(ast::MatchArm::pat)
                 .map(|x| x.syntax().to_string())
                 .collect::<Vec<String>>()
                 .join(" | ")
@@ -96,10 +96,10 @@ pub(crate) fn merge_match_arms(ctx: AssistCtx) -> Option<Assist> {
 }
 
 fn contains_placeholder(a: &ast::MatchArm) -> bool {
-    a.pats().any(|x| match x {
-        ra_syntax::ast::Pat::PlaceholderPat(..) => true,
+    match a.pat() {
+        Some(ra_syntax::ast::Pat::PlaceholderPat(..)) => true,
         _ => false,
-    })
+    }
 }
 
 fn next_arm(arm: &ast::MatchArm) -> Option<ast::MatchArm> {

crates/ra_assists/src/handlers/move_guard.rs

@@ -90,7 +90,7 @@ pub(crate) fn move_guard_to_arm_body(ctx: AssistCtx) -> Option<Assist> {
 // ```
 pub(crate) fn move_arm_cond_to_match_guard(ctx: AssistCtx) -> Option<Assist> {
     let match_arm: MatchArm = ctx.find_node_at_offset::<MatchArm>()?;
-    let last_match_pat = match_arm.pats().last()?;
+    let match_pat = match_arm.pat()?;
 
     let arm_body = match_arm.expr()?;
     let if_expr: IfExpr = IfExpr::cast(arm_body.syntax().clone())?;
@@ -122,8 +122,8 @@ pub(crate) fn move_arm_cond_to_match_guard(ctx: AssistCtx) -> Option<Assist> {
                 _ => edit.replace(if_expr.syntax().text_range(), then_block.syntax().text()),
             }
 
-            edit.insert(last_match_pat.syntax().text_range().end(), buf);
-            edit.set_cursor(last_match_pat.syntax().text_range().end() + TextUnit::from(1));
+            edit.insert(match_pat.syntax().text_range().end(), buf);
+            edit.set_cursor(match_pat.syntax().text_range().end() + TextUnit::from(1));
         },
     )
 }

crates/ra_hir_def/src/body/lower.rs

@@ -164,9 +164,9 @@ where
                             let match_expr = self.collect_expr_opt(condition.expr());
                             let placeholder_pat = self.missing_pat();
                             let arms = vec![
-                                MatchArm { pats: vec![pat], expr: then_branch, guard: None },
+                                MatchArm { pat, expr: then_branch, guard: None },
                                 MatchArm {
-                                    pats: vec![placeholder_pat],
+                                    pat: placeholder_pat,
                                     expr: else_branch.unwrap_or_else(|| self.empty_block()),
                                     guard: None,
                                 },
@@ -203,8 +203,8 @@ where
                             let placeholder_pat = self.missing_pat();
                             let break_ = self.alloc_expr_desugared(Expr::Break { expr: None });
                             let arms = vec![
-                                MatchArm { pats: vec![pat], expr: body, guard: None },
-                                MatchArm { pats: vec![placeholder_pat], expr: break_, guard: None },
+                                MatchArm { pat, expr: body, guard: None },
+                                MatchArm { pat: placeholder_pat, expr: break_, guard: None },
                             ];
                             let match_expr =
                                 self.alloc_expr_desugared(Expr::Match { expr: match_expr, arms });
@@ -250,7 +250,7 @@ where
                     match_arm_list
                         .arms()
                         .map(|arm| MatchArm {
-                            pats: arm.pats().map(|p| self.collect_pat(p)).collect(),
+                            pat: self.collect_pat_opt(arm.pat()),
                             expr: self.collect_expr_opt(arm.expr()),
                             guard: arm
                                 .guard()
@@ -587,6 +587,11 @@ where
                 let path = p.path().and_then(|path| self.expander.parse_path(path));
                 path.map(Pat::Path).unwrap_or(Pat::Missing)
             }
+            ast::Pat::OrPat(p) => {
+                let pats = p.pats().map(|p| self.collect_pat(p)).collect();
+                Pat::Or(pats)
+            }
+            ast::Pat::ParenPat(p) => return self.collect_pat_opt(p.pat()),
             ast::Pat::TuplePat(p) => {
                 let args = p.args().map(|p| self.collect_pat(p)).collect();
                 Pat::Tuple(args)

crates/ra_hir_def/src/body/scope.rs

@@ -158,9 +158,7 @@ fn compute_expr_scopes(expr: ExprId, body: &Body, scopes: &mut ExprScopes, scope
             compute_expr_scopes(*expr, body, scopes, scope);
             for arm in arms {
                 let scope = scopes.new_scope(scope);
-                for pat in &arm.pats {
-                    scopes.add_bindings(body, scope, *pat);
-                }
+                scopes.add_bindings(body, scope, arm.pat);
                 scopes.set_scope(arm.expr, scope);
                 compute_expr_scopes(arm.expr, body, scopes, scope);
             }

crates/ra_hir_def/src/expr.rs

@@ -202,7 +202,7 @@ pub enum Array {
 
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub struct MatchArm {
-    pub pats: Vec<PatId>,
+    pub pat: PatId,
     pub guard: Option<ExprId>,
     pub expr: ExprId,
 }
@@ -382,6 +382,7 @@ pub enum Pat {
     Missing,
     Wild,
     Tuple(Vec<PatId>),
+    Or(Vec<PatId>),
     Record {
         path: Option<Path>,
         args: Vec<RecordFieldPat>,
@@ -420,7 +421,7 @@ impl Pat {
             Pat::Bind { subpat, .. } => {
                 subpat.iter().copied().for_each(f);
             }
-            Pat::Tuple(args) | Pat::TupleStruct { args, .. } => {
+            Pat::Or(args) | Pat::Tuple(args) | Pat::TupleStruct { args, .. } => {
                 args.iter().copied().for_each(f);
             }
             Pat::Ref { pat, .. } => f(*pat),

crates/ra_hir_ty/src/infer/expr.rs

@@ -168,9 +168,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                 let mut result_ty = self.table.new_maybe_never_type_var();
 
                 for arm in arms {
-                    for &pat in &arm.pats {
-                        let _pat_ty = self.infer_pat(pat, &input_ty, BindingMode::default());
-                    }
+                    let _pat_ty = self.infer_pat(arm.pat, &input_ty, BindingMode::default());
                     if let Some(guard_expr) = arm.guard {
                         self.infer_expr(
                             guard_expr,

crates/ra_hir_ty/src/infer/pat.rs

@@ -82,6 +82,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
 
         let is_non_ref_pat = match &body[pat] {
             Pat::Tuple(..)
+            | Pat::Or(..)
             | Pat::TupleStruct { .. }
             | Pat::Record { .. }
             | Pat::Range { .. }
@@ -126,6 +127,17 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
 
                 Ty::apply(TypeCtor::Tuple { cardinality: args.len() as u16 }, Substs(inner_tys))
             }
+            Pat::Or(ref pats) => {
+                if let Some((first_pat, rest)) = pats.split_first() {
+                    let ty = self.infer_pat(*first_pat, expected, default_bm);
+                    for pat in rest {
+                        self.infer_pat(*pat, expected, default_bm);
+                    }
+                    ty
+                } else {
+                    Ty::Unknown
+                }
+            }
             Pat::Ref { pat, mutability } => {
                 let expectation = match expected.as_reference() {
                     Some((inner_ty, exp_mut)) => {

crates/ra_ide/src/inlay_hints.rs

@@ -80,8 +80,7 @@ fn get_inlay_hints(
             },
             ast::MatchArmList(it) => {
                 it.arms()
-                    .map(|match_arm| match_arm.pats())
-                    .flatten()
+                    .filter_map(|match_arm| match_arm.pat())
                     .for_each(|root_pat| get_pat_type_hints(acc, db, &analyzer, root_pat, true, max_inlay_hint_length));
             },
             ast::CallExpr(it) => {
@@ -202,6 +201,7 @@ fn get_leaf_pats(root_pat: ast::Pat) -> Vec<ast::Pat> {
                 Some(pat) => pats_to_process.push_back(pat),
                 _ => leaf_pats.push(maybe_leaf_pat),
             },
+            ast::Pat::OrPat(ref_pat) => pats_to_process.extend(ref_pat.pats()),
             ast::Pat::TuplePat(tuple_pat) => pats_to_process.extend(tuple_pat.args()),
             ast::Pat::RecordPat(record_pat) => {
                 if let Some(pat_list) = record_pat.record_field_pat_list() {
@@ -222,6 +222,7 @@ fn get_leaf_pats(root_pat: ast::Pat) -> Vec<ast::Pat> {
             ast::Pat::TupleStructPat(tuple_struct_pat) => {
                 pats_to_process.extend(tuple_struct_pat.args())
             }
+            ast::Pat::ParenPat(inner_pat) => pats_to_process.extend(inner_pat.pat()),
             ast::Pat::RefPat(ref_pat) => pats_to_process.extend(ref_pat.pat()),
             _ => (),
         }

crates/ra_parser/src/grammar/expressions/atom.rs

@@ -336,7 +336,7 @@ fn for_expr(p: &mut Parser, m: Option<Marker>) -> CompletedMarker {
 fn cond(p: &mut Parser) {
     let m = p.start();
     if p.eat(T![let]) {
-        patterns::pattern_list(p);
+        patterns::pattern_top(p);
         p.expect(T![=]);
     }
     expr_no_struct(p);
@@ -430,7 +430,7 @@ fn match_arm(p: &mut Parser) -> BlockLike {
     // }
     attributes::outer_attributes(p);
 
-    patterns::pattern_list_r(p, TokenSet::EMPTY);
+    patterns::pattern_top_r(p, TokenSet::EMPTY);
     if p.at(T![if]) {
         match_guard(p);
     }