rustc: Implement translation of pattern matching for tuple structs and unit-like structs. r=nmatsakis

Author: pcwalton

src/rustc/middle/borrowck/gather_loans.rs

@@ -441,7 +441,8 @@ impl gather_loan_ctxt {
                   alt_id: ast::node_id) {
         do self.bccx.cat_pattern(discr_cmt, root_pat) |cmt, pat| {
             match pat.node {
-              ast::pat_ident(bm, _, _) if !self.pat_is_variant(pat) => {
+              ast::pat_ident(bm, _, _)
+                    if !self.pat_is_variant_or_struct(pat) => {
                 match bm {
                   ast::bind_by_value | ast::bind_by_move => {
                     // copying does not borrow anything, so no check
@@ -492,8 +493,8 @@ impl gather_loan_ctxt {
         }
     }
 
-    fn pat_is_variant(&self, pat: @ast::pat) -> bool {
-        pat_util::pat_is_variant(self.bccx.tcx.def_map, pat)
+    fn pat_is_variant_or_struct(&self, pat: @ast::pat) -> bool {
+        pat_util::pat_is_variant_or_struct(self.bccx.tcx.def_map, pat)
     }
 }
 

src/rustc/middle/pat_util.rs

@@ -7,7 +7,7 @@ use syntax::codemap::span;
 use std::map::HashMap;
 
 export pat_binding_ids, pat_bindings, pat_id_map, PatIdMap;
-export pat_is_variant, pat_is_binding_or_wild;
+export pat_is_variant_or_struct, pat_is_binding_or_wild;
 
 type PatIdMap = std::map::HashMap<ident, node_id>;
 
@@ -21,20 +21,21 @@ fn pat_id_map(dm: resolve::DefMap, pat: @pat) -> PatIdMap {
     return map;
 }
 
-fn pat_is_variant(dm: resolve::DefMap, pat: @pat) -> bool {
+fn pat_is_variant_or_struct(dm: resolve::DefMap, pat: @pat) -> bool {
     match pat.node {
-      pat_enum(_, _) => true,
-      pat_ident(_, _, None) | pat_struct(*) => match dm.find(pat.id) {
-        Some(def_variant(_, _)) => true,
+        pat_enum(_, _) | pat_ident(_, _, None) | pat_struct(*) => {
+            match dm.find(pat.id) {
+                Some(def_variant(*)) | Some(def_class(*)) => true,
+                _ => false
+            }
+        }
         _ => false
-      },
-      _ => false
     }
 }
 
 fn pat_is_binding_or_wild(dm: resolve::DefMap, pat: @pat) -> bool {
     match pat.node {
-        pat_ident(*) => !pat_is_variant(dm, pat),
+        pat_ident(*) => !pat_is_variant_or_struct(dm, pat),
         pat_wild => true,
         _ => false
     }
@@ -44,7 +45,8 @@ fn pat_bindings(dm: resolve::DefMap, pat: @pat,
                 it: fn(binding_mode, node_id, span, @path)) {
     do walk_pat(pat) |p| {
         match p.node {
-          pat_ident(binding_mode, pth, _) if !pat_is_variant(dm, p) => {
+          pat_ident(binding_mode, pth, _)
+                if !pat_is_variant_or_struct(dm, p) => {
             it(binding_mode, p.id, p.span, pth);
           }
           _ => {}

src/rustc/middle/resolve.rs

@@ -288,10 +288,10 @@ impl AllowCapturingSelfFlag : cmp::Eq {
     pure fn ne(other: &AllowCapturingSelfFlag) -> bool { !self.eq(other) }
 }
 
-enum EnumVariantOrConstResolution {
-    FoundEnumVariant(def),
+enum BareIdentifierPatternResolution {
+    FoundStructOrEnumVariant(def),
     FoundConst,
-    EnumVariantOrConstNotFound
+    BareIdentifierPatternUnresolved
 }
 
 // Specifies how duplicates should be handled when adding a child item if
@@ -4187,28 +4187,31 @@ impl Resolver {
                         if !path.global && path.idents.len() == 1u => {
 
                     // The meaning of pat_ident with no type parameters
-                    // depends on whether an enum variant with that name is in
-                    // scope. The probing lookup has to be careful not to emit
-                    // spurious errors. Only matching patterns (match) can
-                    // match nullary variants. For binding patterns (let),
-                    // matching such a variant is simply disallowed (since
-                    // it's rarely what you want).
+                    // depends on whether an enum variant or unit-like struct
+                    // with that name is in scope. The probing lookup has to
+                    // be careful not to emit spurious errors. Only matching
+                    // patterns (match) can match nullary variants or
+                    // unit-like structs. For binding patterns (let), matching
+                    // such a value is simply disallowed (since it's rarely
+                    // what you want).
 
                     let ident = path.idents[0];
 
-                    match self.resolve_enum_variant_or_const(ident) {
-                        FoundEnumVariant(def) if mode == RefutableMode => {
+                    match self.resolve_bare_identifier_pattern(ident) {
+                        FoundStructOrEnumVariant(def)
+                                if mode == RefutableMode => {
                             debug!("(resolving pattern) resolving `%s` to \
-                                    enum variant",
+                                    struct or enum variant",
                                     self.session.str_of(ident));
 
                             self.record_def(pattern.id, def);
                         }
-                        FoundEnumVariant(_) => {
+                        FoundStructOrEnumVariant(_) => {
                             self.session.span_err(pattern.span,
                                                   fmt!("declaration of `%s` \
                                                         shadows an enum \
-                                                        that's in scope",
+                                                        variant or unit-like \
+                                                        struct in scope",
                                                         self.session
                                                         .str_of(ident)));
                         }
@@ -4218,7 +4221,7 @@ impl Resolver {
                                                    conflicts with a constant \
                                                    in scope");
                         }
-                        EnumVariantOrConstNotFound => {
+                        BareIdentifierPatternUnresolved => {
                             debug!("(resolving pattern) binding `%s`",
                                    self.session.str_of(ident));
 
@@ -4349,13 +4352,11 @@ impl Resolver {
         }
     }
 
-    fn resolve_enum_variant_or_const(name: ident)
-                                  -> EnumVariantOrConstResolution {
-
+    fn resolve_bare_identifier_pattern(name: ident)
+                                    -> BareIdentifierPatternResolution {
         match self.resolve_item_in_lexical_scope(self.current_module,
-                                               name,
-                                               ValueNS) {
-
+                                                 name,
+                                                 ValueNS) {
             Success(target) => {
                 match target.bindings.value_def {
                     None => {
@@ -4364,14 +4365,14 @@ impl Resolver {
                     }
                     Some(def) => {
                         match def.def {
-                            def @ def_variant(*) => {
-                                return FoundEnumVariant(def);
+                            def @ def_variant(*) | def @ def_class(*) => {
+                                return FoundStructOrEnumVariant(def);
                             }
                             def_const(*) => {
                                 return FoundConst;
                             }
                             _ => {
-                                return EnumVariantOrConstNotFound;
+                                return BareIdentifierPatternUnresolved;
                             }
                         }
                     }
@@ -4383,7 +4384,7 @@ impl Resolver {
             }
 
             Failed => {
-                return EnumVariantOrConstNotFound;
+                return BareIdentifierPatternUnresolved;
             }
         }
     }