Revert "Remove rule requiring non-nil block-style statements to be semi-terminated"

This reverts commit 0f5eaef5fb.

src/libsyntax/ast.rs

@@ -243,7 +243,12 @@ type stmt = spanned<stmt_>;
 #[auto_serialize]
 enum stmt_ {
     stmt_decl(@decl, node_id),
+
+    // expr without trailing semi-colon (must have unit type):
     stmt_expr(@expr, node_id),
+
+    // expr with trailing semi-colon (may have any type):
+    stmt_semi(@expr, node_id),
 }
 
 #[auto_serialize]

src/libsyntax/ast_util.rs

@@ -38,6 +38,7 @@ pure fn stmt_id(s: stmt) -> node_id {
     alt s.node {
       stmt_decl(_, id) { id }
       stmt_expr(_, id) { id }
+      stmt_semi(_, id) { id }
     }
 }
 

src/libsyntax/ext/auto_serialize.rs

@@ -206,7 +206,7 @@ impl helpers for ext_ctxt {
     }
 
     fn stmt(expr: @ast::expr) -> @ast::stmt {
-        @{node: ast::stmt_expr(expr, self.next_id()),
+        @{node: ast::stmt_semi(expr, self.next_id()),
           span: expr.span}
     }
 

src/libsyntax/fold.rs

@@ -315,6 +315,7 @@ fn noop_fold_stmt(s: stmt_, fld: ast_fold) -> stmt_ {
     ret alt s {
       stmt_decl(d, nid) { stmt_decl(fld.fold_decl(d), fld.new_id(nid)) }
       stmt_expr(e, nid) { stmt_expr(fld.fold_expr(e), fld.new_id(nid)) }
+      stmt_semi(e, nid) { stmt_semi(fld.fold_expr(e), fld.new_id(nid)) }
     };
 }
 

src/libsyntax/parse/classify.rs

@@ -27,6 +27,9 @@ fn stmt_ends_with_semi(stmt: ast::stmt) -> bool {
       ast::stmt_expr(e, _) {
         ret expr_requires_semi_to_be_stmt(e);
       }
+      ast::stmt_semi(e, _) {
+        ret false;
+      }
     }
 }
 

src/libsyntax/parse/parser.rs

@@ -1848,7 +1848,7 @@ class parser {
                       token::SEMI {
                         self.bump();
                         push(stmts,
-                             @{node: stmt_expr(e, stmt_id) with *stmt});
+                             @{node: stmt_semi(e, stmt_id) with *stmt});
                       }
                       token::RBRACE {
                         expr = some(e);

src/libsyntax/print/pprust.rs

@@ -682,9 +682,11 @@ fn print_stmt(s: ps, st: ast::stmt) {
       ast::stmt_expr(expr, _) {
         space_if_not_bol(s);
         print_expr(s, expr);
-        if expr_requires_semi_to_be_stmt(expr) {
+      }
-            word(s.s, ";");
+      ast::stmt_semi(expr, _) {
-        }
+        space_if_not_bol(s);
+        print_expr(s, expr);
+        word(s.s, ";");
       }
     }
     if parse::classify::stmt_ends_with_semi(st) { word(s.s, ";"); }

src/libsyntax/visit.rs

@@ -320,6 +320,7 @@ fn visit_stmt<E>(s: @stmt, e: E, v: vt<E>) {
     alt s.node {
       stmt_decl(d, _) { v.visit_decl(d, e, v); }
       stmt_expr(ex, _) { v.visit_expr(ex, e, v); }
+      stmt_semi(ex, _) { v.visit_expr(ex, e, v); }
     }
 }
 

src/rustc/front/test.rs

@@ -359,7 +359,7 @@ fn mk_test_wrapper(cx: test_ctxt,
     };
 
     let call_stmt: ast::stmt = nospan(
-        ast::stmt_expr(@call_expr, cx.sess.next_node_id()));
+        ast::stmt_semi(@call_expr, cx.sess.next_node_id()));
 
     let wrapper_decl: ast::fn_decl = {
         inputs: ~[],

src/rustc/middle/astencode.rs

@@ -229,7 +229,7 @@ fn simplify_ast(ii: ast::inlined_item) -> ast::inlined_item {
     fn drop_nested_items(blk: ast::blk_, fld: fold::ast_fold) -> ast::blk_ {
         let stmts_sans_items = do vec::filter(blk.stmts) |stmt| {
             alt stmt.node {
-              ast::stmt_expr(_, _) |
+              ast::stmt_expr(_, _) | ast::stmt_semi(_, _) |
               ast::stmt_decl(@{node: ast::decl_local(_), span: _}, _) { true }
               ast::stmt_decl(@{node: ast::decl_item(_), span: _}, _) { false }
             }

src/rustc/middle/lint.rs

@@ -405,7 +405,7 @@ fn check_item_path_statement(cx: ty::ctxt, it: @ast::item) {
     let visit = item_stopping_visitor(visit::mk_simple_visitor(@{
         visit_stmt: fn@(s: @ast::stmt) {
             alt s.node {
-              ast::stmt_expr(@{id: id,
+              ast::stmt_semi(@{id: id,
                                node: ast::expr_path(@path),
                                span: _}, _) {
                 cx.sess.span_lint(

src/rustc/middle/liveness.rs

@@ -843,7 +843,7 @@ class liveness {
             ret self.propagate_through_decl(decl, succ);
           }
 
-          stmt_expr(expr, _) {
+          stmt_expr(expr, _) | stmt_semi(expr, _) {
             ret self.propagate_through_expr(expr, succ);
           }
         }

src/rustc/middle/trans/base.rs

@@ -4131,7 +4131,7 @@ fn trans_stmt(cx: block, s: ast::stmt) -> block {
     debuginfo::update_source_pos(cx, s.span);
 
     alt s.node {
-      ast::stmt_expr(e, _) {
+      ast::stmt_expr(e, _) | ast::stmt_semi(e, _) {
         bcx = trans_expr(cx, e, ignore);
       }
       ast::stmt_decl(d, _) {

src/rustc/middle/tstate/annotate.rs

@@ -15,7 +15,7 @@ fn collect_ids_block(b: blk, rs: @mut ~[node_id]) {
 
 fn collect_ids_stmt(s: @stmt, rs: @mut ~[node_id]) {
     alt s.node {
-      stmt_decl(_, id) | stmt_expr(_, id) {
+      stmt_decl(_, id) | stmt_expr(_, id) | stmt_semi(_, id) {
         #debug["node_id %s", int::str(id)];
         #debug["%s", stmt_to_str(*s)];
         vec::push(*rs, id);

src/rustc/middle/tstate/auxiliary.rs

@@ -278,7 +278,7 @@ fn node_id_to_poststate(ccx: crate_ctxt, id: node_id) -> poststate {
 fn stmt_to_ann(ccx: crate_ctxt, s: stmt) -> ts_ann {
     #debug("stmt_to_ann");
     alt s.node {
-      stmt_decl(_, id) | stmt_expr(_, id) {
+      stmt_decl(_, id) | stmt_expr(_, id) | stmt_semi(_, id) {
         ret node_id_to_ts_ann(ccx, id);
       }
     }

src/rustc/middle/tstate/pre_post_conditions.rs

@@ -520,7 +520,7 @@ fn find_pre_post_stmt(fcx: fn_ctxt, s: stmt) {
           }
         }
       }
-      stmt_expr(e, id) {
+      stmt_expr(e, id) | stmt_semi(e, id) {
         find_pre_post_expr(fcx, e);
         copy_pre_post(fcx.ccx, id, e);
       }

src/rustc/middle/tstate/states.rs

@@ -537,7 +537,7 @@ fn find_pre_post_state_stmt(fcx: fn_ctxt, pres: prestate, s: @stmt) -> bool {
           }
         }
       }
-      stmt_expr(ex, _) {
+      stmt_expr(ex, _) | stmt_semi(ex, _) {
         let mut changed =
             find_pre_post_state_expr(fcx, pres, ex) |
                 set_prestate(stmt_ann, expr_prestate(fcx.ccx, ex)) |

src/rustc/middle/ty.rs

@@ -2255,7 +2255,7 @@ fn expr_is_lval(method_map: typeck::method_map, e: @ast::expr) -> bool {
 
 fn stmt_node_id(s: @ast::stmt) -> ast::node_id {
     alt s.node {
-      ast::stmt_decl(_, id) | stmt_expr(_, id) {
+      ast::stmt_decl(_, id) | stmt_expr(_, id) | stmt_semi(_, id) {
         ret id;
       }
     }

src/rustc/middle/typeck/check.rs

@@ -1718,6 +1718,10 @@ fn check_stmt(fcx: @fn_ctxt, stmt: @ast::stmt) -> bool {
         }
       }
       ast::stmt_expr(expr, id) {
+        node_id = id;
+        bot = check_expr_with(fcx, expr, ty::mk_nil(fcx.ccx.tcx));
+      }
+      ast::stmt_semi(expr, id) {
         node_id = id;
         bot = check_expr(fcx, expr, none);
       }
@@ -1749,7 +1753,7 @@ fn check_block(fcx0: @fn_ctxt, blk: ast::blk) -> bool {
         if bot && !warned &&
                alt s.node {
                  ast::stmt_decl(@{node: ast::decl_local(_), _}, _) |
-                 ast::stmt_expr(_, _) {
+                 ast::stmt_expr(_, _) | ast::stmt_semi(_, _) {
                    true
                  }
                  _ { false }

src/test/compile-fail/block-arg-as-stmt-with-value.rs

@@ -2,13 +2,12 @@
 fn compute1() -> float {
     let v = ~[0f, 1f, 2f, 3f];
 
-    // This is actually a (block-style) statement followed by
-    // a unary tail expression
     do vec::foldl(0f, v) |x, y| { x + y } - 10f
+    //~^ ERROR mismatched types: expected `()`
 }
 
 fn main() {
     let x = compute1();
     log(debug, x);
-    assert(x == -10f);
+    assert(x == -4f);
 }

src/test/run-pass/typed-statements-dont-need-semis.rs

@@ -1,13 +0,0 @@
-fn f(f: fn()) -> int {
-    f(); 0
-}
-
-fn main() {
-    // Testing that the old rule that statements (even control
-    // structures) that have non-nil type be semi-terminated _no
-    // longer_ is required
-    do f {
-    }
-    if true { 0 } else { 0 }
-    let _x = 0;
-}