syntax: make OptVec immutable.

This is the first step to replacing OptVec with a new representation:
remove all mutability. Any mutations have to go via `Vec` and then make
to `OptVec`.

Many of the uses of OptVec are unnecessary now that Vec has no-alloc
emptiness (and have been converted to Vec): the only ones that really
need it are the AST and sty's (and so on) where there are a *lot* of
instances of them, and they're (mostly) immutable.

Author: huonw

src/librustc/metadata/tydecode.rs

@@ -192,13 +192,13 @@ fn parse_region_substs(st: &mut PState, conv: conv_did) -> ty::RegionSubsts {
     match next(st) {
         'e' => ty::ErasedRegions,
         'n' => {
-            let mut regions = opt_vec::Empty;
+            let mut regions = vec!();
             while peek(st) != '.' {
                 let r = parse_region(st, |x,y| conv(x,y));
                 regions.push(r);
             }
             assert_eq!(next(st), '.');
-            ty::NonerasedRegions(regions)
+            ty::NonerasedRegions(opt_vec::from(regions))
         }
         _ => fail!("parse_bound_region: bad input")
     }

src/librustc/middle/borrowck/move_data.rs

@@ -26,8 +26,6 @@ use middle::typeck;
 use syntax::ast;
 use syntax::ast_util;
 use syntax::codemap::Span;
-use syntax::opt_vec::OptVec;
-use syntax::opt_vec;
 use util::ppaux::Repr;
 
 pub struct MoveData {
@@ -316,15 +314,15 @@ impl MoveData {
 
     fn existing_base_paths(&self,
                            lp: @LoanPath)
-                           -> OptVec<MovePathIndex> {
-        let mut result = opt_vec::Empty;
+                           -> Vec<MovePathIndex> {
+        let mut result = vec!();
         self.add_existing_base_paths(lp, &mut result);
         result
     }
 
     fn add_existing_base_paths(&self,
                                lp: @LoanPath,
-                               result: &mut OptVec<MovePathIndex>) {
+                               result: &mut Vec<MovePathIndex>) {
         /*!
          * Adds any existing move path indices for `lp` and any base
          * paths of `lp` to `result`, but does not add new move paths

src/librustc/middle/cfg/construct.rs

@@ -14,7 +14,6 @@ use middle::typeck;
 use middle::ty;
 use syntax::ast;
 use syntax::ast_util;
-use syntax::opt_vec;
 use util::nodemap::NodeMap;
 
 struct CFGBuilder<'a> {
@@ -470,7 +469,7 @@ impl<'a> CFGBuilder<'a> {
     fn add_contained_edge(&mut self,
                           source: CFGIndex,
                           target: CFGIndex) {
-        let data = CFGEdgeData {exiting_scopes: opt_vec::Empty};
+        let data = CFGEdgeData {exiting_scopes: vec!() };
         self.graph.add_edge(source, target, data);
     }
 
@@ -479,9 +478,10 @@ impl<'a> CFGBuilder<'a> {
                         from_index: CFGIndex,
                         to_loop: LoopScope,
                         to_index: CFGIndex) {
-        let mut data = CFGEdgeData {exiting_scopes: opt_vec::Empty};
+        let mut data = CFGEdgeData {exiting_scopes: vec!() };
         let mut scope_id = from_expr.id;
         while scope_id != to_loop.loop_id {
+
             data.exiting_scopes.push(scope_id);
             scope_id = self.tcx.region_maps.encl_scope(scope_id);
         }

src/librustc/middle/cfg/mod.rs

@@ -19,7 +19,6 @@ use middle::graph;
 use middle::ty;
 use middle::typeck;
 use syntax::ast;
-use syntax::opt_vec::OptVec;
 use util::nodemap::NodeMap;
 
 mod construct;
@@ -36,7 +35,7 @@ pub struct CFGNodeData {
 }
 
 pub struct CFGEdgeData {
-    exiting_scopes: OptVec<ast::NodeId>
+    exiting_scopes: Vec<ast::NodeId>
 }
 
 pub type CFGIndex = graph::NodeIndex;

src/librustc/middle/resolve_lifetime.rs

@@ -21,7 +21,6 @@ use driver::session::Session;
 use util::nodemap::NodeMap;
 use syntax::ast;
 use syntax::codemap::Span;
-use syntax::opt_vec;
 use syntax::opt_vec::OptVec;
 use syntax::parse::token::special_idents;
 use syntax::parse::token;
@@ -413,22 +412,22 @@ pub fn early_bound_lifetimes<'a>(generics: &'a ast::Generics) -> Vec<ast::Lifeti
         .collect()
 }
 
-pub fn free_lifetimes(ty_params: &OptVec<ast::TyParam>) -> OptVec<ast::Name> {
+pub fn free_lifetimes(ty_params: &OptVec<ast::TyParam>) -> Vec<ast::Name> {
     /*!
      * Gathers up and returns the names of any lifetimes that appear
      * free in `ty_params`. Of course, right now, all lifetimes appear
      * free, since we don't currently have any binders in type parameter
      * declarations; just being forwards compatible with future extensions.
      */
 
-    let mut collector = FreeLifetimeCollector { names: opt_vec::Empty };
+    let mut collector = FreeLifetimeCollector { names: vec!() };
     for ty_param in ty_params.iter() {
         visit::walk_ty_param_bounds(&mut collector, &ty_param.bounds, ());
     }
     return collector.names;
 
     struct FreeLifetimeCollector {
-        names: OptVec<ast::Name>,
+        names: Vec<ast::Name>,
     }
 
     impl Visitor<()> for FreeLifetimeCollector {

src/librustc/middle/trans/cleanup.rs

@@ -24,8 +24,6 @@ use middle::trans::glue;
 use middle::trans::type_::Type;
 use middle::ty;
 use syntax::ast;
-use syntax::opt_vec;
-use syntax::opt_vec::OptVec;
 use util::ppaux::Repr;
 
 pub struct CleanupScope<'a> {
@@ -37,9 +35,9 @@ pub struct CleanupScope<'a> {
     kind: CleanupScopeKind<'a>,
 
     // Cleanups to run upon scope exit.
-    cleanups: OptVec<~Cleanup>,
+    cleanups: Vec<~Cleanup>,
 
-    cached_early_exits: OptVec<CachedEarlyExit>,
+    cached_early_exits: Vec<CachedEarlyExit>,
     cached_landing_pad: Option<BasicBlockRef>,
 }
 
@@ -379,7 +377,7 @@ impl<'a> CleanupMethods<'a> for FunctionContext<'a> {
         assert!(orig_scopes_len > 0);
 
         // Remove any scopes that do not have cleanups on failure:
-        let mut popped_scopes = opt_vec::Empty;
+        let mut popped_scopes = vec!();
         while !self.top_scope(|s| s.needs_invoke()) {
             debug!("top scope does not need invoke");
             popped_scopes.push(self.pop_scope());
@@ -510,7 +508,7 @@ impl<'a> CleanupHelperMethods<'a> for FunctionContext<'a> {
 
         let orig_scopes_len = self.scopes_len();
         let mut prev_llbb;
-        let mut popped_scopes = opt_vec::Empty;
+        let mut popped_scopes = vec!();
 
         // First we pop off all the cleanup stacks that are
         // traversed until the exit is reached, pushing them
@@ -708,14 +706,14 @@ impl<'a> CleanupScope<'a> {
     fn new(kind: CleanupScopeKind<'a>) -> CleanupScope<'a> {
         CleanupScope {
             kind: kind,
-            cleanups: opt_vec::Empty,
-            cached_early_exits: opt_vec::Empty,
+            cleanups: vec!(),
+            cached_early_exits: vec!(),
             cached_landing_pad: None,
         }
     }
 
     fn clear_cached_exits(&mut self) {
-        self.cached_early_exits = opt_vec::Empty;
+        self.cached_early_exits = vec!();
         self.cached_landing_pad = None;
     }
 

src/librustc/middle/ty.rs

@@ -5072,11 +5072,10 @@ pub fn construct_parameter_environment(
 
     // map bound 'a => free 'a
     let region_params = {
-        fn push_region_params(accum: OptVec<ty::Region>,
+        fn push_region_params(mut accum: Vec<ty::Region>,
                               free_id: ast::NodeId,
                               region_params: &[RegionParameterDef])
-                              -> OptVec<ty::Region> {
-            let mut accum = accum;
+                              -> Vec<ty::Region> {
             for r in region_params.iter() {
                 accum.push(
                     ty::ReFree(ty::FreeRegion {
@@ -5086,14 +5085,14 @@ pub fn construct_parameter_environment(
             accum
         }
 
-        let t = push_region_params(opt_vec::Empty, free_id, item_region_params);
+        let t = push_region_params(vec!(), free_id, item_region_params);
         push_region_params(t, free_id, method_region_params)
     };
 
     let free_substs = substs {
         self_ty: self_ty,
         tps: type_params,
-        regions: ty::NonerasedRegions(region_params)
+        regions: ty::NonerasedRegions(opt_vec::from(region_params))
     };
 
     //

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

@@ -104,6 +104,7 @@ use syntax::ast::{MutMutable, MutImmutable};
 use syntax::ast;
 use syntax::codemap::Span;
 use syntax::parse::token;
+use syntax::opt_vec;
 
 #[deriving(Eq)]
 pub enum CheckTraitsFlag {
@@ -1102,8 +1103,8 @@ impl<'a> LookupContext<'a> {
 
         // Determine values for the early-bound lifetime parameters.
         // FIXME -- permit users to manually specify lifetimes
-        let mut all_regions = match candidate.rcvr_substs.regions {
-            NonerasedRegions(ref v) => v.clone(),
+        let mut all_regions: Vec<Region> = match candidate.rcvr_substs.regions {
+            NonerasedRegions(ref v) => v.iter().map(|r| r.clone()).collect(),
             ErasedRegions => tcx.sess.span_bug(self.span, "ErasedRegions")
         };
         let m_regions =
@@ -1119,7 +1120,7 @@ impl<'a> LookupContext<'a> {
         let all_substs = substs {
             tps: vec::append(candidate.rcvr_substs.tps.clone(),
                                 m_substs.as_slice()),
-            regions: NonerasedRegions(all_regions),
+            regions: NonerasedRegions(opt_vec::from(all_regions)),
             self_ty: candidate.rcvr_substs.self_ty,
         };
 

src/librustc/middle/typeck/infer/combine.rs

@@ -160,7 +160,7 @@ pub trait Combine {
 
                     assert_eq!(num_region_params, a_rs.len());
                     assert_eq!(num_region_params, b_rs.len());
-                    let mut rs = opt_vec::Empty;
+                    let mut rs = vec!();
                     for i in range(0, num_region_params) {
                         let a_r = *a_rs.get(i);
                         let b_r = *b_rs.get(i);
@@ -176,7 +176,7 @@ pub trait Combine {
                         };
                         rs.push(if_ok!(r));
                     }
-                    Ok(ty::NonerasedRegions(rs))
+                    Ok(ty::NonerasedRegions(opt_vec::from(rs)))
                 }
             }
         }

src/librustc/middle/typeck/infer/error_reporting.rs

@@ -80,8 +80,6 @@ use syntax::ast;
 use syntax::ast_map;
 use syntax::ast_util;
 use syntax::ast_util::name_to_dummy_lifetime;
-use syntax::opt_vec;
-use syntax::opt_vec::OptVec;
 use syntax::parse::token;
 use syntax::print::pprust;
 use util::ppaux::UserString;
@@ -90,10 +88,10 @@ use util::ppaux::note_and_explain_region;
 
 pub trait ErrorReporting {
     fn report_region_errors(&self,
-                            errors: &OptVec<RegionResolutionError>);
+                            errors: &Vec<RegionResolutionError>);
 
-    fn process_errors(&self, errors: &OptVec<RegionResolutionError>)
-                      -> OptVec<RegionResolutionError>;
+    fn process_errors(&self, errors: &Vec<RegionResolutionError>)
+                      -> Vec<RegionResolutionError>;
 
     fn report_type_error(&self, trace: TypeTrace, terr: &ty::type_err);
 
@@ -151,7 +149,7 @@ trait ErrorReportingHelpers {
 
 impl<'a> ErrorReporting for InferCtxt<'a> {
     fn report_region_errors(&self,
-                            errors: &OptVec<RegionResolutionError>) {
+                            errors: &Vec<RegionResolutionError>) {
         let p_errors = self.process_errors(errors);
         let errors = if p_errors.is_empty() { errors } else { &p_errors };
         for error in errors.iter() {
@@ -195,12 +193,12 @@ impl<'a> ErrorReporting for InferCtxt<'a> {
     // complete view of what lifetimes should be the same.
     // If the return value is an empty vector, it means that processing
     // failed (so the return value of this method should not be used)
-    fn process_errors(&self, errors: &OptVec<RegionResolutionError>)
-                      -> OptVec<RegionResolutionError> {
+    fn process_errors(&self, errors: &Vec<RegionResolutionError>)
+                      -> Vec<RegionResolutionError> {
         let mut var_origins = Vec::new();
         let mut trace_origins = Vec::new();
         let mut same_regions = Vec::new();
-        let mut processed_errors = opt_vec::Empty;
+        let mut processed_errors = Vec::new();
         for error in errors.iter() {
             match *error {
                 ConcreteFailure(origin, sub, sup) => {
@@ -239,7 +237,7 @@ impl<'a> ErrorReporting for InferCtxt<'a> {
                 // declaration, we want to make sure that they are, in fact,
                 // from the same scope
                 if sr.scope_id != common_scope_id {
-                    return opt_vec::Empty;
+                    return vec!();
                 }
             }
             let pe = ProcessedErrors(var_origins, trace_origins, same_regions);