From ac216880f5d1a3e5727b96d7b22433beec10382b Mon Sep 17 00:00:00 2001
From: Marcus Klaas de Vries <mail@marcusklaas.nl>
Date: Thu, 17 Jan 2019 00:08:10 +0100
Subject: Implement unlabeled struct field pattern inference

---
 crates/ra_hir/src/expr.rs     | 11 ++++++-----
 crates/ra_hir/src/ty.rs       | 15 ++++-----------
 crates/ra_hir/src/ty/tests.rs |  5 +++++
 crates/ra_syntax/src/ast.rs   | 42 +++++++++++-------------------------------
 4 files changed, 26 insertions(+), 47 deletions(-)

diff --git a/crates/ra_hir/src/expr.rs b/crates/ra_hir/src/expr.rs
index 893bad9cd..e7235c1a1 100644
--- a/crates/ra_hir/src/expr.rs
+++ b/crates/ra_hir/src/expr.rs
@@ -332,7 +332,7 @@ impl_arena_id!(PatId);
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub struct FieldPat {
     pub(crate) name: Name,
-    pub(crate) pat: Option<PatId>,
+    pub(crate) pat: PatId,
 }
 
 /// Close relative to rustc's hir::PatKind
@@ -393,7 +393,7 @@ impl Pat {
                 total_iter.map(|pat| *pat).for_each(f);
             }
             Pat::Struct { args, .. } => {
-                args.iter().filter_map(|a| a.pat).for_each(f);
+                args.iter().map(|f| f.pat).for_each(f);
             }
         }
     }
@@ -821,9 +821,10 @@ impl ExprCollector {
                     .expect("every struct should have a field list")
                     .field_pats()
                     .into_iter()
-                    .map(|f| FieldPat {
-                        name: Name::new(f.ident),
-                        pat: f.pat.as_ref().map(|p| self.collect_pat(p)),
+                    .map(|f| {
+                        let name = Name::new(f.ident);
+                        let pat = self.collect_pat(&*f.pat);
+                        FieldPat { name, pat }
                     })
                     .collect();
 
diff --git a/crates/ra_hir/src/ty.rs b/crates/ra_hir/src/ty.rs
index 6bad61a2a..66940ec30 100644
--- a/crates/ra_hir/src/ty.rs
+++ b/crates/ra_hir/src/ty.rs
@@ -937,19 +937,12 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
         };
 
         for sub_pat in sub_pats {
-            let tyref = fields
-                .iter()
-                .find(|field| field.name == sub_pat.name)
-                .map(|field| &field.type_ref);
+            let matching_field = fields.iter().find(|field| field.name == sub_pat.name);
 
-            if let Some(typeref) = tyref {
+            if let Some(field) = matching_field {
+                let typeref = &field.type_ref;
                 let sub_ty = Ty::from_hir(self.db, &self.module, self.impl_block.as_ref(), typeref);
-
-                if let Some(pat) = sub_pat.pat {
-                    self.infer_pat(pat, &Expectation::has_type(sub_ty));
-                } else {
-                    // TODO: deal with this case: S { x, y }
-                }
+                self.infer_pat(sub_pat.pat, &Expectation::has_type(sub_ty));
             }
         }
 
diff --git a/crates/ra_hir/src/ty/tests.rs b/crates/ra_hir/src/ty/tests.rs
index 75fe2cc6e..10842f967 100644
--- a/crates/ra_hir/src/ty/tests.rs
+++ b/crates/ra_hir/src/ty/tests.rs
@@ -389,6 +389,11 @@ fn test() {
 
     let S(y, z) = foo;
     let E::A { x: new_var } = e;
+
+    match e {
+        E::A { x } => x,
+        E::B => 1,
+    };
 }
 "#,
         "adt_pattern.txt",
diff --git a/crates/ra_syntax/src/ast.rs b/crates/ra_syntax/src/ast.rs
index 3df23b16f..4b7edbbe7 100644
--- a/crates/ra_syntax/src/ast.rs
+++ b/crates/ra_syntax/src/ast.rs
@@ -664,36 +664,11 @@ impl LiteralExpr {
     }
 }
 
-// STRUCT_PAT@[20; 42)
-//   PATH@[20; 26)
-//     PATH_SEGMENT@[20; 26)
-//       NAME_REF@[20; 26)
-//         IDENT@[20; 26) "Strukt"
-//   WHITESPACE@[26; 27)
-//   FIELD_PAT_LIST@[27; 42)
-//     L_CURLY@[27; 28)
-//     WHITESPACE@[28; 29)
-//     IDENT@[29; 30) "x"
-//     COLON@[30; 31)
-//     WHITESPACE@[31; 32)
-//     BIND_PAT@[32; 33)
-//       NAME@[32; 33)
-//         IDENT@[32; 33) "x"
-//     COMMA@[33; 34)
-//     WHITESPACE@[34; 35)
-//     BIND_PAT@[35; 36)
-//       NAME@[35; 36)
-//         IDENT@[35; 36) "y"
-//     COMMA@[36; 37)
-//     WHITESPACE@[37; 38)
-//     DOTDOT@[38; 40)
-//     WHITESPACE@[40; 41)
-//     R_CURLY@[41; 42)
-
 #[derive(Clone, Debug, PartialEq, Eq, Hash)]
 pub struct FieldPat {
     pub ident: SmolStr,
-    pub pat: Option<TreeArc<Pat>>,
+    // FIXME: could we use a regular reference?
+    pub pat: TreeArc<Pat>,
 }
 
 impl FieldPatList {
@@ -704,12 +679,17 @@ impl FieldPatList {
         let mut pats = Vec::new();
 
         while let Some(node) = child_iter.next() {
-            if node.kind() != IDENT {
+            let kind = node.kind();
+            if kind != IDENT && kind != BIND_PAT {
                 continue;
             }
 
-            let ident = node.leaf_text().unwrap().clone();
-            let mut pat = None;
+            let ident = if let Some(text) = node.leaf_text() {
+                text.clone()
+            } else {
+                SmolStr::new(node.text().to_string())
+            };
+            let mut pat = Pat::cast(node).map(AstNode::to_owned);
 
             // get pat
             while let Some(node) = child_iter.next() {
@@ -724,7 +704,7 @@ impl FieldPatList {
 
             let field_pat = FieldPat {
                 ident: ident,
-                pat: pat,
+                pat: pat.unwrap(),
             };
             pats.push(field_pat);
         }
-- 
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