auto merge of #9103 : jbclements/rust/let-var-hygiene, r=erickt

update AST so that ExprBreak and ExprCont expressions contain names, not idents. Fixes #9047 and makes progress on #6993. Simplifies the compiler very slightly, should make it (infinitesimally) faster.

Author: bors

src/librustc/middle/cfg/construct.rs

@@ -488,7 +488,7 @@ impl CFGBuilder {
 
     fn find_scope(&self,
                   expr: @ast::Expr,
-                  label: Option<ast::Ident>) -> LoopScope {
+                  label: Option<ast::Name>) -> LoopScope {
         match label {
             None => {
                 return *self.loop_scopes.last();

src/librustc/middle/dataflow.rs

@@ -867,7 +867,7 @@ impl<'self, O:DataFlowOperator> PropagationContext<'self, O> {
 
     fn find_scope<'a>(&self,
                       expr: @ast::Expr,
-                      label: Option<ast::Ident>,
+                      label: Option<ast::Name>,
                       loop_scopes: &'a mut ~[LoopScope]) -> &'a mut LoopScope {
         let index = match label {
             None => {

src/librustc/middle/liveness.rs

@@ -756,7 +756,7 @@ impl Liveness {
     }
 
     pub fn find_loop_scope(&self,
-                           opt_label: Option<Ident>,
+                           opt_label: Option<Name>,
                            id: NodeId,
                            sp: Span)
                            -> NodeId {

src/librustc/middle/resolve.rs

@@ -5157,15 +5157,13 @@ impl Resolver {
             ExprForLoop(*) => fail!("non-desugared expr_for_loop"),
 
             ExprBreak(Some(label)) | ExprAgain(Some(label)) => {
-                let name = label.name;
-                match self.search_ribs(self.label_ribs, name, expr.span,
+                match self.search_ribs(self.label_ribs, label, expr.span,
                                        DontAllowCapturingSelf) {
                     None =>
                         self.resolve_error(expr.span,
                                               fmt!("use of undeclared label \
                                                    `%s`",
-                                                   self.session.str_of(
-                                                       label))),
+                                                   interner_get(label))),
                     Some(DlDef(def @ DefLabel(_))) => {
                         self.record_def(expr.id, def)
                     }

src/librustc/middle/trans/base.rs

@@ -76,7 +76,7 @@ use std::vec;
 use std::local_data;
 use extra::time;
 use extra::sort;
-use syntax::ast::Ident;
+use syntax::ast::Name;
 use syntax::ast_map::{path, path_elt_to_str, path_name, path_pretty_name};
 use syntax::ast_util::{local_def};
 use syntax::attr;
@@ -1189,7 +1189,7 @@ pub fn scope_block(bcx: @mut Block,
 
 pub fn loop_scope_block(bcx: @mut Block,
                         loop_break: @mut Block,
-                        loop_label: Option<Ident>,
+                        loop_label: Option<Name>,
                         n: &str,
                         opt_node_info: Option<NodeInfo>) -> @mut Block {
     return new_block(bcx.fcx, Some(bcx), Some(@mut ScopeInfo {

src/librustc/middle/trans/common.rs

@@ -38,7 +38,7 @@ use std::cast;
 use std::hashmap::{HashMap};
 use std::libc::{c_uint, c_longlong, c_ulonglong, c_char};
 use std::vec;
-use syntax::ast::Ident;
+use syntax::ast::{Name,Ident};
 use syntax::ast_map::{path, path_elt, path_pretty_name};
 use syntax::codemap::Span;
 use syntax::parse::token;
@@ -463,7 +463,7 @@ pub fn block_cleanups(bcx: @mut Block) -> ~[cleanup] {
 pub struct ScopeInfo {
     parent: Option<@mut ScopeInfo>,
     loop_break: Option<@mut Block>,
-    loop_label: Option<Ident>,
+    loop_label: Option<Name>,
     // A list of functions that must be run at when leaving this
     // block, cleaning up any variables that were introduced in the
     // block.

src/librustc/middle/trans/controlflow.rs

@@ -22,7 +22,7 @@ use util::ppaux;
 use middle::trans::type_::Type;
 
 use syntax::ast;
-use syntax::ast::Ident;
+use syntax::ast::Name;
 use syntax::ast_util;
 use syntax::codemap::Span;
 
@@ -188,7 +188,7 @@ pub fn trans_while(bcx: @mut Block, cond: @ast::Expr, body: &ast::Block) -> @mut
 
 pub fn trans_loop(bcx:@mut Block,
                   body: &ast::Block,
-                  opt_label: Option<Ident>)
+                  opt_label: Option<Name>)
                -> @mut Block {
     let _icx = push_ctxt("trans_loop");
     let next_bcx = sub_block(bcx, "next");
@@ -201,7 +201,7 @@ pub fn trans_loop(bcx:@mut Block,
 }
 
 pub fn trans_break_cont(bcx: @mut Block,
-                        opt_label: Option<Ident>,
+                        opt_label: Option<Name>,
                         to_end: bool)
                      -> @mut Block {
     let _icx = push_ctxt("trans_break_cont");
@@ -254,11 +254,11 @@ pub fn trans_break_cont(bcx: @mut Block,
     return bcx;
 }
 
-pub fn trans_break(bcx: @mut Block, label_opt: Option<Ident>) -> @mut Block {
+pub fn trans_break(bcx: @mut Block, label_opt: Option<Name>) -> @mut Block {
     return trans_break_cont(bcx, label_opt, true);
 }
 
-pub fn trans_cont(bcx: @mut Block, label_opt: Option<Ident>) -> @mut Block {
+pub fn trans_cont(bcx: @mut Block, label_opt: Option<Name>) -> @mut Block {
     return trans_break_cont(bcx, label_opt, false);
 }
 

src/librustc/middle/trans/expr.rs

@@ -617,7 +617,8 @@ fn trans_rvalue_stmt_unadjusted(bcx: @mut Block, expr: @ast::Expr) -> @mut Block
             return controlflow::trans_while(bcx, cond, body);
         }
         ast::ExprLoop(ref body, opt_label) => {
-            return controlflow::trans_loop(bcx, body, opt_label);
+            // FIXME #6993: map can go away when ast.rs is changed
+            return controlflow::trans_loop(bcx, body, opt_label.map(|x| x.name));
         }
         ast::ExprAssign(dst, src) => {
             let src_datum = unpack_datum!(

src/libsyntax/ast.rs

@@ -522,10 +522,12 @@ pub enum Expr_ {
     ExprCast(@Expr, Ty),
     ExprIf(@Expr, Block, Option<@Expr>),
     ExprWhile(@Expr, Block),
+    // FIXME #6993: change to Option<Name>
     ExprForLoop(@Pat, @Expr, Block, Option<Ident>),
     /* Conditionless loop (can be exited with break, cont, or ret)
        Same semantics as while(true) { body }, but typestate knows that the
        (implicit) condition is always true. */
+    // FIXME #6993: change to Option<Name>
     ExprLoop(Block, Option<Ident>),
     ExprMatch(@Expr, ~[Arm]),
     ExprFnBlock(fn_decl, Block),
@@ -541,8 +543,8 @@ pub enum Expr_ {
     /// The special identifier `self`.
     ExprSelf,
     ExprAddrOf(Mutability, @Expr),
-    ExprBreak(Option<Ident>),
-    ExprAgain(Option<Ident>),
+    ExprBreak(Option<Name>),
+    ExprAgain(Option<Name>),
     ExprRet(Option<@Expr>),
 
     /// Gets the log level for the enclosing module

src/libsyntax/ext/expand.rs

@@ -113,6 +113,7 @@ pub fn expand_expr(extsbox: @mut SyntaxEnv,
 
         // Desugar expr_for_loop
         // From: `['<ident>:] for <src_pat> in <src_expr> <src_loop_block>`
+        // FIXME #6993 : change type of opt_ident to Option<Name>
         ast::ExprForLoop(src_pat, src_expr, ref src_loop_block, opt_ident) => {
             // Expand any interior macros etc.
             // NB: we don't fold pats yet. Curious.
@@ -144,7 +145,8 @@ pub fn expand_expr(extsbox: @mut SyntaxEnv,
 
             // `None => break ['<ident>];`
             let none_arm = {
-                let break_expr = cx.expr(span, ast::ExprBreak(opt_ident));
+                // FIXME #6993: this map goes away:
+                let break_expr = cx.expr(span, ast::ExprBreak(opt_ident.map(|x| x.name)));
                 let none_pat = cx.pat_ident(span, none_ident);
                 cx.arm(span, ~[none_pat], break_expr)
             };