Stop passing around Option<&substs> in trans and just pass &substs, making the code more regular

Author: nikomatsakis

src/librustc/middle/subst.rs

@@ -63,6 +63,14 @@ impl Substs {
         }
     }
 
+    pub fn trans_empty() -> Substs {
+        Substs {
+            self_ty: None,
+            tps: Vec::new(),
+            regions: ErasedRegions
+        }
+    }
+
     pub fn is_noop(&self) -> bool {
         let regions_is_noop = match self.regions {
             ErasedRegions => false, // may be used to canonicalize

src/librustc/middle/trans/base.rs

@@ -1098,19 +1098,19 @@ pub fn new_fn_ctxt<'a>(ccx: &'a CrateContext,
                        id: ast::NodeId,
                        has_env: bool,
                        output_type: ty::t,
-                       param_substs: Option<&'a param_substs>,
+                       param_substs: &'a param_substs,
                        sp: Option<Span>,
                        block_arena: &'a TypedArena<Block<'a>>)
                        -> FunctionContext<'a> {
-    for p in param_substs.iter() { p.validate(); }
+    param_substs.validate();
 
     debug!("new_fn_ctxt(path={}, id={}, param_substs={})",
            if id == -1 {
                "".to_string()
            } else {
                ccx.tcx.map.path_to_str(id).to_string()
            },
-           id, param_substs.map(|s| s.repr(ccx.tcx())));
+           id, param_substs.repr(ccx.tcx()));
 
     let substd_output_type = output_type.substp(ccx.tcx(), param_substs);
     let uses_outptr = type_of::return_uses_outptr(ccx, substd_output_type);
@@ -1303,7 +1303,7 @@ pub fn trans_closure(ccx: &CrateContext,
                      decl: &ast::FnDecl,
                      body: &ast::Block,
                      llfndecl: ValueRef,
-                     param_substs: Option<&param_substs>,
+                     param_substs: &param_substs,
                      id: ast::NodeId,
                      _attributes: &[ast::Attribute],
                      output_type: ty::t,
@@ -1314,7 +1314,7 @@ pub fn trans_closure(ccx: &CrateContext,
     set_uwtable(llfndecl);
 
     debug!("trans_closure(..., param_substs={})",
-           param_substs.map(|s| s.repr(ccx.tcx())));
+           param_substs.repr(ccx.tcx()));
 
     let has_env = match ty::get(ty::node_id_to_type(ccx.tcx(), id)).sty {
         ty::ty_closure(_) => true,
@@ -1327,7 +1327,7 @@ pub fn trans_closure(ccx: &CrateContext,
                           id,
                           has_env,
                           output_type,
-                          param_substs.map(|s| &*s),
+                          param_substs,
                           Some(body.span),
                           &arena);
     init_function(&fcx, false, output_type);
@@ -1403,11 +1403,11 @@ pub fn trans_fn(ccx: &CrateContext,
                 decl: &ast::FnDecl,
                 body: &ast::Block,
                 llfndecl: ValueRef,
-                param_substs: Option<&param_substs>,
+                param_substs: &param_substs,
                 id: ast::NodeId,
                 attrs: &[ast::Attribute]) {
     let _s = StatRecorder::new(ccx, ccx.tcx.map.path_to_str(id).to_string());
-    debug!("trans_fn(param_substs={})", param_substs.map(|s| s.repr(ccx.tcx())));
+    debug!("trans_fn(param_substs={})", param_substs.repr(ccx.tcx()));
     let _icx = push_ctxt("trans_fn");
     let output_type = ty::ty_fn_ret(ty::node_id_to_type(ccx.tcx(), id));
     trans_closure(ccx, decl, body, llfndecl,
@@ -1419,7 +1419,7 @@ pub fn trans_enum_variant(ccx: &CrateContext,
                           variant: &ast::Variant,
                           _args: &[ast::VariantArg],
                           disr: ty::Disr,
-                          param_substs: Option<&param_substs>,
+                          param_substs: &param_substs,
                           llfndecl: ValueRef) {
     let _icx = push_ctxt("trans_enum_variant");
 
@@ -1434,7 +1434,7 @@ pub fn trans_enum_variant(ccx: &CrateContext,
 pub fn trans_tuple_struct(ccx: &CrateContext,
                           _fields: &[ast::StructField],
                           ctor_id: ast::NodeId,
-                          param_substs: Option<&param_substs>,
+                          param_substs: &param_substs,
                           llfndecl: ValueRef) {
     let _icx = push_ctxt("trans_tuple_struct");
 
@@ -1449,7 +1449,7 @@ pub fn trans_tuple_struct(ccx: &CrateContext,
 fn trans_enum_variant_or_tuple_like_struct(ccx: &CrateContext,
                                            ctor_id: ast::NodeId,
                                            disr: ty::Disr,
-                                           param_substs: Option<&param_substs>,
+                                           param_substs: &param_substs,
                                            llfndecl: ValueRef) {
     let ctor_ty = ty::node_id_to_type(ccx.tcx(), ctor_id);
     let ctor_ty = ctor_ty.substp(ccx.tcx(), param_substs);
@@ -1464,7 +1464,7 @@ fn trans_enum_variant_or_tuple_like_struct(ccx: &CrateContext,
 
     let arena = TypedArena::new();
     let fcx = new_fn_ctxt(ccx, llfndecl, ctor_id, false, result_ty,
-                          param_substs.map(|s| &*s), None, &arena);
+                          param_substs, None, &arena);
     init_function(&fcx, false, result_ty);
 
     let arg_tys = ty::ty_fn_args(ctor_ty);
@@ -1500,7 +1500,7 @@ fn trans_enum_def(ccx: &CrateContext, enum_definition: &ast::EnumDef,
             ast::TupleVariantKind(ref args) if args.len() > 0 => {
                 let llfn = get_item_val(ccx, variant.node.id);
                 trans_enum_variant(ccx, id, variant, args.as_slice(),
-                                   disr_val, None, llfn);
+                                   disr_val, &param_substs::empty(), llfn);
             }
             ast::TupleVariantKind(_) => {
                 // Nothing to do.
@@ -1587,7 +1587,7 @@ pub fn trans_item(ccx: &CrateContext, item: &ast::Item) {
                      decl,
                      body,
                      llfn,
-                     None,
+                     &param_substs::empty(),
                      item.id,
                      item.attrs.as_slice());
         } else {
@@ -1660,7 +1660,7 @@ pub fn trans_struct_def(ccx: &CrateContext, struct_def: @ast::StructDef) {
         Some(ctor_id) if struct_def.fields.len() > 0 => {
             let llfndecl = get_item_val(ccx, ctor_id);
             trans_tuple_struct(ccx, struct_def.fields.as_slice(),
-                               ctor_id, None, llfndecl);
+                               ctor_id, &param_substs::empty(), llfndecl);
         }
         Some(_) | None => {}
     }

src/librustc/middle/trans/callee.rs

@@ -187,7 +187,7 @@ fn trans_fn_ref_with_vtables_to_callee<'a>(bcx: &'a Block<'a>,
                                            def_id: ast::DefId,
                                            ref_id: ast::NodeId,
                                            substs: subst::Substs,
-                                           vtables: Option<typeck::vtable_res>)
+                                           vtables: typeck::vtable_res)
                                            -> Callee<'a> {
     Callee {bcx: bcx,
             data: Fn(trans_fn_ref_with_vtables(bcx, def_id, ExprId(ref_id),
@@ -198,8 +198,9 @@ fn resolve_default_method_vtables(bcx: &Block,
                                   impl_id: ast::DefId,
                                   method: &ty::Method,
                                   substs: &subst::Substs,
-                                  impl_vtables: Option<typeck::vtable_res>)
-                          -> (typeck::vtable_res, typeck::vtable_param_res) {
+                                  impl_vtables: typeck::vtable_res)
+                          -> (typeck::vtable_res, typeck::vtable_param_res)
+{
 
     // Get the vtables that the impl implements the trait at
     let impl_res = ty::lookup_impl_vtables(bcx.tcx(), impl_id);
@@ -213,27 +214,15 @@ fn resolve_default_method_vtables(bcx: &Block,
     };
 
     let mut param_vtables = resolve_vtables_under_param_substs(
-        bcx.tcx(), Some(&param_substs), impl_res.trait_vtables.as_slice());
+        bcx.tcx(), &param_substs, impl_res.trait_vtables.as_slice());
 
     // Now we pull any vtables for parameters on the actual method.
     let num_method_vtables = method.generics.type_param_defs().len();
-    match impl_vtables {
-        Some(ref vtables) => {
-            let num_impl_type_parameters =
-                vtables.len() - num_method_vtables;
-            param_vtables.push_all(vtables.tailn(num_impl_type_parameters))
-        },
-        None => {
-            param_vtables.extend(range(0, num_method_vtables).map(
-                |_| -> typeck::vtable_param_res {
-                    Vec::new()
-                }
-            ))
-        }
-    }
+    let num_impl_type_parameters = impl_vtables.len() - num_method_vtables;
+    param_vtables.push_all(impl_vtables.tailn(num_impl_type_parameters));
 
     let self_vtables = resolve_param_vtables_under_param_substs(
-        bcx.tcx(), Some(&param_substs), impl_res.self_vtables.as_slice());
+        bcx.tcx(), &param_substs, impl_res.self_vtables.as_slice());
 
     (param_vtables, self_vtables)
 }
@@ -244,7 +233,7 @@ pub fn trans_fn_ref_with_vtables(
         def_id: ast::DefId,   // def id of fn
         node: ExprOrMethodCall,  // node id of use of fn; may be zero if N/A
         substs: subst::Substs, // values for fn's ty params
-        vtables: Option<typeck::vtable_res>) // vtables for the call
+        vtables: typeck::vtable_res) // vtables for the call
      -> ValueRef {
     /*!
      * Translates a reference to a fn/method item, monomorphizing and
@@ -336,7 +325,7 @@ pub fn trans_fn_ref_with_vtables(
                    self_vtables.repr(tcx), param_vtables.repr(tcx));
 
             (true, source_id,
-             new_substs, Some(self_vtables), Some(param_vtables))
+             new_substs, Some(self_vtables), param_vtables)
         }
     };
 
@@ -507,7 +496,7 @@ pub fn trans_lang_call<'a>(
                                                                     did,
                                                                     0,
                                                                     subst::Substs::empty(),
-                                                                    None)
+                                                                    Vec::new())
                              },
                              ArgVals(args),
                              dest)

src/librustc/middle/trans/closure.rs

@@ -421,7 +421,9 @@ pub fn get_wrapper_for_bare_fn(ccx: &CrateContext,
     let _icx = push_ctxt("closure::get_wrapper_for_bare_fn");
 
     let arena = TypedArena::new();
-    let fcx = new_fn_ctxt(ccx, llfn, -1, true, f.sig.output, None, None, &arena);
+    let empty_param_substs = param_substs::empty();
+    let fcx = new_fn_ctxt(ccx, llfn, -1, true, f.sig.output,
+                          &empty_param_substs, None, &arena);
     init_function(&fcx, true, f.sig.output);
     let bcx = fcx.entry_bcx.borrow().clone().unwrap();
 

src/librustc/middle/trans/common.rs

@@ -180,11 +180,19 @@ pub type ExternMap = HashMap<String, ValueRef>;
 // will only be set in the case of default methods.
 pub struct param_substs {
     pub substs: subst::Substs,
-    pub vtables: Option<typeck::vtable_res>,
+    pub vtables: typeck::vtable_res,
     pub self_vtables: Option<typeck::vtable_param_res>
 }
 
 impl param_substs {
+    pub fn empty() -> param_substs {
+        param_substs {
+            substs: subst::Substs::trans_empty(),
+            vtables: Vec::new(),
+            self_vtables: None
+        }
+    }
+
     pub fn validate(&self) {
         for t in self.substs.tps.iter() {
             assert!(!ty::type_needs_infer(*t));
@@ -206,21 +214,13 @@ impl Repr for param_substs {
 }
 
 pub trait SubstP {
-    fn substp(&self, tcx: &ty::ctxt, param_substs: Option<&param_substs>)
+    fn substp(&self, tcx: &ty::ctxt, param_substs: &param_substs)
               -> Self;
 }
 
 impl<T:Subst+Clone> SubstP for T {
-    fn substp(&self, tcx: &ty::ctxt, param_substs: Option<&param_substs>)
-              -> T {
-        match param_substs {
-            Some(substs) => {
-                self.subst(tcx, &substs.substs)
-            }
-            None => {
-                (*self).clone()
-            }
-        }
+    fn substp(&self, tcx: &ty::ctxt, substs: &param_substs) -> T {
+        self.subst(tcx, &substs.substs)
     }
 }
 
@@ -281,7 +281,7 @@ pub struct FunctionContext<'a> {
 
     // If this function is being monomorphized, this contains the type
     // substitutions used.
-    pub param_substs: Option<&'a param_substs>,
+    pub param_substs: &'a param_substs,
 
     // The source span and nesting context where this function comes from, for
     // error reporting and symbol generation.
@@ -697,16 +697,7 @@ pub fn is_null(val: ValueRef) -> bool {
 }
 
 pub fn monomorphize_type(bcx: &Block, t: ty::t) -> ty::t {
-    match bcx.fcx.param_substs {
-        Some(ref substs) => {
-            t.subst(bcx.tcx(), &substs.substs)
-        }
-        _ => {
-            assert!(!ty::type_has_params(t));
-            assert!(!ty::type_has_self(t));
-            t
-        }
-    }
+    t.subst(bcx.tcx(), &bcx.fcx.param_substs.substs)
 }
 
 pub fn node_id_type(bcx: &Block, id: ast::NodeId) -> ty::t {
@@ -759,10 +750,10 @@ pub fn node_id_substs(bcx: &Block,
 }
 
 pub fn node_vtables(bcx: &Block, id: typeck::MethodCall)
-                 -> Option<typeck::vtable_res> {
+                 -> typeck::vtable_res {
     bcx.tcx().vtable_map.borrow().find(&id).map(|vts| {
         resolve_vtables_in_fn_ctxt(bcx.fcx, vts.as_slice())
-    })
+    }).unwrap_or_else(|| Vec::new())
 }
 
 // Apply the typaram substitutions in the FunctionContext to some
@@ -776,7 +767,7 @@ pub fn resolve_vtables_in_fn_ctxt(fcx: &FunctionContext,
 }
 
 pub fn resolve_vtables_under_param_substs(tcx: &ty::ctxt,
-                                          param_substs: Option<&param_substs>,
+                                          param_substs: &param_substs,
                                           vts: &[typeck::vtable_param_res])
                                           -> typeck::vtable_res {
     vts.iter().map(|ds| {
@@ -788,7 +779,7 @@ pub fn resolve_vtables_under_param_substs(tcx: &ty::ctxt,
 
 pub fn resolve_param_vtables_under_param_substs(
     tcx: &ty::ctxt,
-    param_substs: Option<&param_substs>,
+    param_substs: &param_substs,
     ds: &[typeck::vtable_origin])
     -> typeck::vtable_param_res {
     ds.iter().map(|d| {
@@ -801,7 +792,7 @@ pub fn resolve_param_vtables_under_param_substs(
 
 
 pub fn resolve_vtable_under_param_substs(tcx: &ty::ctxt,
-                                         param_substs: Option<&param_substs>,
+                                         param_substs: &param_substs,
                                          vt: &typeck::vtable_origin)
                                          -> typeck::vtable_origin {
     match *vt {
@@ -812,16 +803,7 @@ pub fn resolve_vtable_under_param_substs(tcx: &ty::ctxt,
                 resolve_vtables_under_param_substs(tcx, param_substs, sub.as_slice()))
         }
         typeck::vtable_param(n_param, n_bound) => {
-            match param_substs {
-                Some(substs) => {
-                    find_vtable(tcx, substs, n_param, n_bound)
-                }
-                _ => {
-                    tcx.sess.bug(format!(
-                        "resolve_vtable_under_param_substs: asked to lookup \
-                         but no vtables in the fn_ctxt!").as_slice())
-                }
-            }
+            find_vtable(tcx, param_substs, n_param, n_bound)
         }
     }
 }
@@ -837,9 +819,7 @@ pub fn find_vtable(tcx: &ty::ctxt,
     let param_bounds = match n_param {
         typeck::param_self => ps.self_vtables.as_ref().expect("self vtables missing"),
         typeck::param_numbered(n) => {
-            let tables = ps.vtables.as_ref()
-                .expect("vtables missing where they are needed");
-            tables.get(n)
+            ps.vtables.get(n)
         }
     };
     param_bounds.get(n_bound).clone()