auto merge of #10366 : brson/rust/ignore-patterns, r=alexcrichton

This replaces `*` with `..` in enums, `_` with `..` in structs, and `.._` with `..` in vectors. It adds obsolete syntax warnings for the old forms but doesn't turn them on yet because we need a snapshot.

#5830

Author: bors

src/librustc/middle/cfg/construct.rs

@@ -97,7 +97,7 @@ impl CFGBuilder {
             ast::PatEnum(_, None) |
             ast::PatLit(*) |
             ast::PatRange(*) |
-            ast::PatWild => {
+            ast::PatWild | ast::PatWildMulti => {
                 self.add_node(pat.id, [pred])
             }
 

src/librustc/middle/check_match.rs

@@ -333,7 +333,7 @@ fn is_useful_specialized(cx: &MatchCheckCtxt,
 fn pat_ctor_id(cx: &MatchCheckCtxt, p: @Pat) -> Option<ctor> {
     let pat = raw_pat(p);
     match pat.node {
-      PatWild => { None }
+      PatWild | PatWildMulti => { None }
       PatIdent(_, _, _) | PatEnum(_, _) => {
         match cx.tcx.def_map.find(&pat.id) {
           Some(&DefVariant(_, id, _)) => Some(variant(id)),
@@ -369,7 +369,7 @@ fn pat_ctor_id(cx: &MatchCheckCtxt, p: @Pat) -> Option<ctor> {
 fn is_wild(cx: &MatchCheckCtxt, p: @Pat) -> bool {
     let pat = raw_pat(p);
     match pat.node {
-      PatWild => { true }
+      PatWild | PatWildMulti => { true }
       PatIdent(_, _, _) => {
         match cx.tcx.def_map.find(&pat.id) {
           Some(&DefVariant(_, _, _)) | Some(&DefStatic(*)) => { false }
@@ -532,6 +532,10 @@ fn wild() -> @Pat {
     @Pat {id: 0, node: PatWild, span: dummy_sp()}
 }
 
+fn wild_multi() -> @Pat {
+    @Pat {id: 0, node: PatWildMulti, span: dummy_sp()}
+}
+
 fn specialize(cx: &MatchCheckCtxt,
                   r: &[@Pat],
                   ctor_id: &ctor,
@@ -546,6 +550,9 @@ fn specialize(cx: &MatchCheckCtxt,
             PatWild => {
                 Some(vec::append(vec::from_elem(arity, wild()), r.tail()))
             }
+            PatWildMulti => {
+                Some(vec::append(vec::from_elem(arity, wild_multi()), r.tail()))
+            }
             PatIdent(_, _, _) => {
                 match cx.tcx.def_map.find(&pat_id) {
                     Some(&DefVariant(_, id, _)) => {
@@ -849,7 +856,7 @@ fn is_refutable(cx: &MatchCheckCtxt, pat: &Pat) -> bool {
       PatIdent(_, _, Some(sub)) => {
         is_refutable(cx, sub)
       }
-      PatWild | PatIdent(_, _, None) => { false }
+      PatWild | PatWildMulti | PatIdent(_, _, None) => { false }
       PatLit(@Expr {node: ExprLit(@Spanned { node: lit_nil, _}), _}) => {
         // "()"
         false

src/librustc/middle/mem_categorization.rs

@@ -876,7 +876,7 @@ impl mem_categorization_ctxt {
         op(cmt, pat);
 
         match pat.node {
-          ast::PatWild => {
+          ast::PatWild | ast::PatWildMulti => {
             // _
           }
 

src/librustc/middle/pat_util.rs

@@ -65,7 +65,7 @@ pub fn pat_is_binding(dm: resolve::DefMap, pat: @Pat) -> bool {
 pub fn pat_is_binding_or_wild(dm: resolve::DefMap, pat: @Pat) -> bool {
     match pat.node {
         PatIdent(*) => pat_is_binding(dm, pat),
-        PatWild => true,
+        PatWild | PatWildMulti => true,
         _ => false
     }
 }

src/librustc/middle/trans/_match.rs

@@ -545,7 +545,7 @@ fn enter_default<'r>(bcx: @mut Block,
     // Collect all of the matches that can match against anything.
     let matches = do enter_match(bcx, dm, m, col, val) |p| {
         match p.node {
-          ast::PatWild | ast::PatTup(_) => Some(~[]),
+          ast::PatWild | ast::PatWildMulti | ast::PatTup(_) => Some(~[]),
           ast::PatIdent(_, _, None) if pat_is_binding(dm, p) => Some(~[]),
           _ => None
         }
@@ -2234,7 +2234,7 @@ fn bind_irrefutable_pat(bcx: @mut Block,
                 pat.span,
                 format!("vector patterns are never irrefutable!"));
         }
-        ast::PatWild | ast::PatLit(_) | ast::PatRange(_, _) => ()
+        ast::PatWild | ast::PatWildMulti | ast::PatLit(_) | ast::PatRange(_, _) => ()
     }
     return bcx;
 }

src/librustc/middle/trans/debuginfo.rs

@@ -2429,7 +2429,7 @@ fn populate_scope_map(cx: &mut CrateContext,
                 }
             }
 
-            ast::PatWild => {
+            ast::PatWild | ast::PatWildMulti => {
                 scope_map.insert(pat.id, scope_stack.last().scope_metadata);
             }
 

src/librustc/middle/typeck/check/_match.rs

@@ -414,7 +414,7 @@ pub fn check_pat(pcx: &pat_ctxt, pat: @ast::Pat, expected: ty::t) {
     let tcx = pcx.fcx.ccx.tcx;
 
     match pat.node {
-      ast::PatWild => {
+      ast::PatWild | ast::PatWildMulti => {
         fcx.write_ty(pat.id, expected);
       }
       ast::PatLit(lt) => {

src/librustc/middle/typeck/check/regionck.rs

@@ -1219,7 +1219,7 @@ pub mod guarantor {
                rcx.fcx.pat_to_str(pat), guarantor);
 
         match pat.node {
-            ast::PatWild => {}
+            ast::PatWild | ast::PatWildMulti => {}
             ast::PatIdent(ast::BindByRef(_), _, opt_p) => {
                 link(rcx, pat.span, pat.id, guarantor);
 

src/librustdoc/clean.rs

@@ -1137,6 +1137,7 @@ fn name_from_pat(p: &ast::Pat) -> ~str {
     use syntax::ast::*;
     match p.node {
         PatWild => ~"_",
+        PatWildMulti => ~"..",
         PatIdent(_, ref p, _) => path_to_str(p),
         PatEnum(ref p, _) => path_to_str(p),
         PatStruct(*) => fail!("tried to get argument name from pat_struct, \

src/libsyntax/ast.rs

@@ -337,6 +337,7 @@ pub enum BindingMode {
 #[deriving(Clone, Eq, Encodable, Decodable, IterBytes)]
 pub enum Pat_ {
     PatWild,
+    PatWildMulti,
     // A pat_ident may either be a new bound variable,
     // or a nullary enum (in which case the second field
     // is None).

src/libsyntax/ast_util.rs

@@ -657,7 +657,7 @@ pub fn walk_pat(pat: @Pat, it: &fn(@Pat) -> bool) -> bool {
                 slice.iter().advance(|&p| walk_pat(p, |p| it(p))) &&
                 after.iter().advance(|&p| walk_pat(p, |p| it(p)))
         }
-        PatWild | PatLit(_) | PatRange(_, _) | PatIdent(_, _, _) |
+        PatWild | PatWildMulti | PatLit(_) | PatRange(_, _) | PatIdent(_, _, _) |
         PatEnum(_, _) => {
             true
         }

src/libsyntax/fold.rs

@@ -174,6 +174,7 @@ pub trait ast_fold {
     fn fold_pat(&self, p: @Pat) -> @Pat {
         let node = match p.node {
             PatWild => PatWild,
+            PatWildMulti => PatWildMulti,
             PatIdent(binding_mode, ref pth, ref sub) => {
                 PatIdent(binding_mode,
                          self.fold_path(pth),

src/libsyntax/parse/obsolete.rs

@@ -39,6 +39,9 @@ pub enum ObsoleteSyntax {
     ObsoleteConstPointer,
     ObsoleteEmptyImpl,
     ObsoleteLoopAsContinue,
+    ObsoleteEnumWildcard,
+    ObsoleteStructWildcard,
+    ObsoleteVecDotDotWildcard
 }
 
 impl to_bytes::IterBytes for ObsoleteSyntax {
@@ -113,6 +116,18 @@ impl ParserObsoleteMethods for Parser {
                 "`loop` is now only used for loops and `continue` is used for \
                  skipping iterations"
             ),
+            ObsoleteEnumWildcard => (
+                "enum wildcard",
+                "use `..` instead of `*` for matching all enum fields"
+            ),
+            ObsoleteStructWildcard => (
+                "struct wildcard",
+                "use `..` instead of `_` for matching trailing struct fields"
+            ),
+            ObsoleteVecDotDotWildcard => (
+                "vec slice wildcard",
+                "use `..` instead of `.._` for matching slices"
+            ),
         };
 
         self.report(sp, kind, kind_str, desc);

src/libsyntax/parse/parser.rs

@@ -43,7 +43,7 @@ use ast::{MutImmutable, MutMutable, mac_, mac_invoc_tt, matcher, match_nontermin
 use ast::{match_seq, match_tok, method, mt, BiMul, Mutability};
 use ast::{named_field, UnNeg, noreturn, UnNot, Pat, PatBox, PatEnum};
 use ast::{PatIdent, PatLit, PatRange, PatRegion, PatStruct};
-use ast::{PatTup, PatUniq, PatWild, private};
+use ast::{PatTup, PatUniq, PatWild, PatWildMulti, private};
 use ast::{BiRem, required};
 use ast::{ret_style, return_val, BiShl, BiShr, Stmt, StmtDecl};
 use ast::{StmtExpr, StmtSemi, StmtMac, struct_def, struct_field};
@@ -2724,17 +2724,35 @@ impl Parser {
                 }
             }
 
-            let subpat = self.parse_pat();
             if is_slice {
-                match subpat {
-                    @ast::Pat { node: PatWild, _ } => (),
-                    @ast::Pat { node: PatIdent(_, _, _), _ } => (),
-                    @ast::Pat { span, _ } => self.span_fatal(
-                        span, "expected an identifier or `_`"
-                    )
+                if *self.token == token::COMMA || *self.token == token::RBRACKET {
+                    slice = Some(@ast::Pat {
+                        id: ast::DUMMY_NODE_ID,
+                        node: PatWildMulti,
+                        span: *self.span,
+                    })
+                } else {
+                    let subpat = self.parse_pat();
+                    match subpat {
+                        @ast::Pat { id, node: PatWild, span } => {
+                            // NOTE #5830 activate after snapshot
+                            // self.obsolete(*self.span, ObsoleteVecDotDotWildcard);
+                            slice = Some(@ast::Pat {
+                                id: id,
+                                node: PatWildMulti,
+                                span: span
+                            })
+                        },
+                        @ast::Pat { node: PatIdent(_, _, _), _ } => {
+                            slice = Some(subpat);
+                        }
+                        @ast::Pat { span, _ } => self.span_fatal(
+                            span, "expected an identifier or nothing"
+                        )
+                    }
                 }
-                slice = Some(subpat);
             } else {
+                let subpat = self.parse_pat();
                 if before_slice {
                     before.push(subpat);
                 } else {
@@ -2755,7 +2773,12 @@ impl Parser {
             if first { first = false; }
             else { self.expect(&token::COMMA); }
 
+            etc = *self.token == token::UNDERSCORE || *self.token == token::DOTDOT;
             if *self.token == token::UNDERSCORE {
+                // NOTE #5830 activate after snapshot
+                // self.obsolete(*self.span, ObsoleteStructWildcard);
+            }
+            if etc {
                 self.bump();
                 if *self.token != token::RBRACE {
                     self.fatal(
@@ -3016,9 +3039,19 @@ impl Parser {
                                     _ => false,
                                 }
                             };
-                            if is_star {
+                            let is_dotdot = do self.look_ahead(1) |t| {
+                                match *t {
+                                    token::DOTDOT => true,
+                                    _ => false,
+                                }
+                            };
+                            if is_star | is_dotdot {
                                 // This is a "top constructor only" pat
                                 self.bump();
+                                if is_star {
+                                    // NOTE #5830 activate after snapshot
+                                    // self.obsolete(*self.span, ObsoleteEnumWildcard);
+                                }
                                 self.bump();
                                 self.expect(&token::RPAREN);
                                 pat = PatEnum(enum_path, None);

src/libsyntax/print/pprust.rs

@@ -1613,6 +1613,7 @@ pub fn print_pat(s: @ps, pat: &ast::Pat) {
      is that it doesn't matter */
     match pat.node {
       ast::PatWild => word(s.s, "_"),
+      ast::PatWildMulti => word(s.s, ".."),
       ast::PatIdent(binding_mode, ref path, sub) => {
           match binding_mode {
               ast::BindByRef(mutbl) => {
@@ -1701,7 +1702,12 @@ pub fn print_pat(s: @ps, pat: &ast::Pat) {
         }
         for &p in slice.iter() {
             if !before.is_empty() { word_space(s, ","); }
-            word(s.s, "..");
+            match p {
+                @ast::Pat { node: ast::PatWildMulti, _ } => {
+                    // this case is handled by print_pat
+                }
+                _ => word(s.s, ".."),
+            }
             print_pat(s, p);
             if !after.is_empty() { word_space(s, ","); }
         }

src/libsyntax/visit.rs

@@ -375,7 +375,7 @@ pub fn walk_pat<E:Clone, V:Visitor<E>>(visitor: &mut V, pattern: &Pat, env: E) {
             visitor.visit_expr(lower_bound, env.clone());
             visitor.visit_expr(upper_bound, env)
         }
-        PatWild => (),
+        PatWild | PatWildMulti => (),
         PatVec(ref prepattern, ref slice_pattern, ref postpatterns) => {
             for prepattern in prepattern.iter() {
                 visitor.visit_pat(*prepattern, env.clone())

src/test/run-pass/ignore-all-the-things.rs

@@ -0,0 +1,50 @@
+// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+struct Foo(int, int, int, int);
+struct Bar{a: int, b: int, c: int, d: int}
+
+pub fn main() {
+    let Foo(..) = Foo(5, 5, 5, 5);
+    let Foo(*) = Foo(5, 5, 5, 5);
+    let Bar{..} = Bar{a: 5, b: 5, c: 5, d: 5};
+    let Bar{_} = Bar{a: 5, b: 5, c: 5, d: 5};
+    //let (..) = (5, 5, 5, 5);
+    //let Foo(a, b, ..) = Foo(5, 5, 5, 5);
+    //let Foo(.., d) = Foo(5, 5, 5, 5);
+    //let (a, b, ..) = (5, 5, 5, 5);
+    //let (.., c, d) = (5, 5, 5, 5);
+    let Bar{b: b, ..} = Bar{a: 5, b: 5, c: 5, d: 5};
+    let Bar{b: b, _} = Bar{a: 5, b: 5, c: 5, d: 5};
+    match [5, 5, 5, 5] {
+        [..] => { }
+    }
+    match [5, 5, 5, 5] {
+        [a, ..] => { }
+    }
+    match [5, 5, 5, 5] {
+        [.., b] => { }
+    }
+    match [5, 5, 5, 5] {
+        [a, .., b] => { }
+    }
+    match [5, 5, 5] {
+        [.._] => { }
+    }
+    match [5, 5, 5] {
+        [a, .._] => { }
+    }
+    match [5, 5, 5] {
+        [.._, a] => { }
+    }
+    match [5, 5, 5] {
+        [a, .._, b] => { }
+    }
+}