Move checking of whether fields are Sized or not into wf / trait code.

Author: nikomatsakis

mk/crates.mk

@@ -59,6 +59,7 @@ CRATES := $(TARGET_CRATES) $(HOST_CRATES)
 TOOLS := compiletest rustdoc rustc
 
 DEPS_core :=
+DEPS_libc := core
 DEPS_rlibc := core
 DEPS_unicode := core
 DEPS_alloc := core libc native:jemalloc

src/liblibc/lib.rs

@@ -79,6 +79,8 @@
 #![allow(missing_doc)]
 #![allow(non_snake_case)]
 
+extern crate core;
+
 #[cfg(test)] extern crate std;
 #[cfg(test)] extern crate test;
 #[cfg(test)] extern crate native;

src/librustc/diagnostics.rs

@@ -58,8 +58,6 @@ register_diagnostics!(
     E0039,
     E0040,
     E0041,
-    E0042,
-    E0043,
     E0044,
     E0045,
     E0046,
@@ -92,7 +90,6 @@ register_diagnostics!(
     E0075,
     E0076,
     E0077,
-    E0078,
     E0079,
     E0080,
     E0081,

src/librustc/middle/traits/mod.rs

@@ -80,7 +80,10 @@ pub enum ObligationCauseCode {
 
     // Captures of variable the given id by a closure (span is the
     // span of the closure)
-    ClosureCapture(ast::NodeId, Span)
+    ClosureCapture(ast::NodeId, Span),
+
+    // Types of fields (other than the last) in a struct must be sized.
+    FieldSized,
 }
 
 pub type Obligations = subst::VecPerParamSpace<Obligation>;

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

@@ -381,17 +381,6 @@ impl<'a, 'tcx, 'v> Visitor<'v> for CheckItemTypesVisitor<'a, 'tcx> {
     }
 }
 
-struct CheckItemSizedTypesVisitor<'a, 'tcx: 'a> {
-    ccx: &'a CrateCtxt<'a, 'tcx>
-}
-
-impl<'a, 'tcx, 'v> Visitor<'v> for CheckItemSizedTypesVisitor<'a, 'tcx> {
-    fn visit_item(&mut self, i: &ast::Item) {
-        check_item_sized(self.ccx, i);
-        visit::walk_item(self, i);
-    }
-}
-
 pub fn check_item_types(ccx: &CrateCtxt) {
     let krate = ccx.tcx.map.krate();
     let mut visit = wf::CheckTypeWellFormedVisitor::new(ccx);
@@ -405,9 +394,6 @@ pub fn check_item_types(ccx: &CrateCtxt) {
     visit::walk_crate(&mut visit, krate);
 
     ccx.tcx.sess.abort_if_errors();
-
-    let mut visit = CheckItemSizedTypesVisitor { ccx: ccx };
-    visit::walk_crate(&mut visit, krate);
 }
 
 fn check_bare_fn(ccx: &CrateCtxt,
@@ -670,33 +656,6 @@ fn check_for_field_shadowing(tcx: &ty::ctxt,
     }
 }
 
-fn check_fields_sized(tcx: &ty::ctxt,
-                      struct_def: &ast::StructDef) {
-    let len = struct_def.fields.len();
-    if len == 0 {
-        return;
-    }
-    for f in struct_def.fields.slice_to(len - 1).iter() {
-        let t = ty::node_id_to_type(tcx, f.node.id);
-        if !ty::type_is_sized(tcx, t) {
-            match f.node.kind {
-                ast::NamedField(ident, _) => {
-                    span_err!(tcx.sess, f.span, E0042,
-                        "type `{}` is dynamically sized. \
-                         dynamically sized types may only \
-                         appear as the type of the final \
-                         field in a struct",
-                        token::get_ident(ident));
-                }
-                ast::UnnamedField(_) => {
-                    span_err!(tcx.sess, f.span, E0043,
-                        "dynamically sized type in field");
-                }
-            }
-        }
-    }
-}
-
 pub fn check_struct(ccx: &CrateCtxt, id: ast::NodeId, span: Span) {
     let tcx = ccx.tcx;
 
@@ -711,24 +670,6 @@ pub fn check_struct(ccx: &CrateCtxt, id: ast::NodeId, span: Span) {
     }
 }
 
-pub fn check_item_sized(ccx: &CrateCtxt, it: &ast::Item) {
-    debug!("check_item(it.id={}, it.ident={})",
-           it.id,
-           ty::item_path_str(ccx.tcx, local_def(it.id)));
-    let _indenter = indenter();
-
-    match it.node {
-        ast::ItemEnum(ref enum_definition, _) => {
-            check_enum_variants_sized(ccx,
-                                      enum_definition.variants.as_slice());
-        }
-        ast::ItemStruct(..) => {
-            check_fields_sized(ccx.tcx, &*ccx.tcx.map.expect_struct(it.id));
-        }
-        _ => {}
-    }
-}
-
 pub fn check_item(ccx: &CrateCtxt, it: &ast::Item) {
     debug!("check_item(it.id={}, it.ident={})",
            it.id,
@@ -4946,39 +4887,6 @@ pub fn check_simd(tcx: &ty::ctxt, sp: Span, id: ast::NodeId) {
     }
 }
 
-
-pub fn check_enum_variants_sized(ccx: &CrateCtxt,
-                                 vs: &[P<ast::Variant>]) {
-    for v in vs.iter() {
-        match v.node.kind {
-            ast::TupleVariantKind(ref args) if args.len() > 0 => {
-                let ctor_ty = ty::node_id_to_type(ccx.tcx, v.node.id);
-                let arg_tys: Vec<ty::t> = ty::ty_fn_args(ctor_ty).iter().map(|a| *a).collect();
-                let len = arg_tys.len();
-                if len == 0 {
-                    return;
-                }
-                for (i, t) in arg_tys.slice_to(len - 1).iter().enumerate() {
-                    // Allow the last field in an enum to be unsized.
-                    // We want to do this so that we can support smart pointers.
-                    // A struct value with an unsized final field is itself
-                    // unsized and we must track this in the type system.
-                    if !ty::type_is_sized(ccx.tcx, *t) {
-                        span_err!(ccx.tcx.sess, args.get(i).ty.span, E0078,
-                            "type `{}` is dynamically sized. dynamically sized types may only \
-                             appear as the final type in a variant",
-                             ppaux::ty_to_string(ccx.tcx, *t));
-                    }
-                }
-            },
-            ast::StructVariantKind(ref struct_def) => {
-                check_fields_sized(ccx.tcx, &**struct_def)
-            }
-            _ => {}
-        }
-    }
-}
-
 pub fn check_enum_variants(ccx: &CrateCtxt,
                            sp: Span,
                            vs: &[P<ast::Variant>],

src/librustc/middle/typeck/check/vtable2.rs

@@ -406,5 +406,10 @@ fn note_obligation_cause(fcx: &FnCtxt,
                        name,
                        trait_name);
         }
+        traits::FieldSized => {
+            span_note!(tcx.sess, obligation.cause.span,
+                       "only the last field of a struct or enum variant \
+                       may have a dynamically sized type")
+        }
     }
 }

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

@@ -59,7 +59,6 @@ impl<'ccx, 'tcx> CheckTypeWellFormedVisitor<'ccx, 'tcx> {
                item.id,
                ty::item_path_str(ccx.tcx, local_def(item.id)));
 
-        let ccx = self.ccx;
         match item.node {
             ast::ItemImpl(..) => {
                 self.check_impl(item);
@@ -70,26 +69,14 @@ impl<'ccx, 'tcx> CheckTypeWellFormedVisitor<'ccx, 'tcx> {
             ast::ItemStatic(..) => {
                 self.check_item_type(item);
             }
-            ast::ItemStruct(..) => {
+            ast::ItemStruct(ref struct_def, _) => {
                 self.check_type_defn(item, |fcx| {
-                    ty::struct_fields(ccx.tcx, local_def(item.id),
-                                      &fcx.inh.param_env.free_substs)
-                        .iter()
-                        .map(|f| f.mt.ty)
-                        .collect()
+                    vec![struct_variant(fcx, &**struct_def)]
                 });
             }
-            ast::ItemEnum(..) => {
+            ast::ItemEnum(ref enum_def, _) => {
                 self.check_type_defn(item, |fcx| {
-                    ty::substd_enum_variants(ccx.tcx, local_def(item.id),
-                                             &fcx.inh.param_env.free_substs)
-                        .iter()
-                        .flat_map(|variant| {
-                            variant.args
-                                .iter()
-                                .map(|&arg_ty| arg_ty)
-                        })
-                        .collect()
+                    enum_variants(fcx, enum_def)
                 });
             }
             _ => {}
@@ -116,22 +103,39 @@ impl<'ccx, 'tcx> CheckTypeWellFormedVisitor<'ccx, 'tcx> {
 
     fn check_type_defn(&mut self,
                        item: &ast::Item,
-                       lookup_fields: |&FnCtxt| -> Vec<ty::t>)
+                       lookup_fields: |&FnCtxt| -> Vec<AdtVariant>)
     {
         /*!
          * In a type definition, we check that to ensure that the types of the fields are
          * well-formed.
          */
 
         self.with_fcx(self.ccx, item, |this, fcx| {
-            let field_tys = lookup_fields(fcx);
+            let variants = lookup_fields(fcx);
             let mut bounds_checker = BoundsChecker::new(fcx, item.span,
                                                         item.id, Some(&mut this.cache));
-            for &ty in field_tys.iter() {
-                // Regions are checked below.
-                bounds_checker.check_traits_in_ty(ty);
+            for variant in variants.iter() {
+                for field in variant.fields.iter() {
+                    // Regions are checked below.
+                    bounds_checker.check_traits_in_ty(field.ty);
+                }
+
+                // For DST, all intermediate types must be sized.
+                if variant.fields.len() > 0 {
+                    for field in variant.fields.init().iter() {
+                        let cause = traits::ObligationCause::new(field.span, traits::FieldSized);
+                        fcx.register_obligation(
+                            traits::obligation_for_builtin_bound(fcx.tcx(),
+                                                                 cause,
+                                                                 field.ty,
+                                                                 ty::BoundSized));
+                    }
+                }
             }
 
+            let field_tys: Vec<ty::t> =
+                variants.iter().flat_map(|v| v.fields.iter().map(|f| f.ty)).collect();
+
             regionck::regionck_ensure_component_tys_wf(
                 fcx, item.span, field_tys.as_slice());
         });
@@ -381,6 +385,62 @@ impl<'cx,'tcx> TypeFolder<'tcx> for BoundsChecker<'cx,'tcx> {
     }
 }
 
+///////////////////////////////////////////////////////////////////////////
+// ADT
+
+struct AdtVariant {
+    fields: Vec<AdtField>,
+}
+
+struct AdtField {
+    ty: ty::t,
+    span: Span,
+}
+
+fn struct_variant(fcx: &FnCtxt, struct_def: &ast::StructDef) -> AdtVariant {
+    let fields =
+        struct_def.fields
+        .iter()
+        .map(|field| {
+            let field_ty = ty::node_id_to_type(fcx.tcx(), field.node.id);
+            let field_ty = field_ty.subst(fcx.tcx(), &fcx.inh.param_env.free_substs);
+            AdtField { ty: field_ty, span: field.span }
+        })
+        .collect();
+    AdtVariant { fields: fields }
+}
+
+fn enum_variants(fcx: &FnCtxt, enum_def: &ast::EnumDef) -> Vec<AdtVariant> {
+    enum_def.variants.iter()
+        .map(|variant| {
+            match variant.node.kind {
+                ast::TupleVariantKind(ref args) if args.len() > 0 => {
+                    let ctor_ty = ty::node_id_to_type(fcx.tcx(), variant.node.id);
+                    let arg_tys = ty::ty_fn_args(ctor_ty);
+                    AdtVariant {
+                        fields: args.iter().enumerate().map(|(index, arg)| {
+                            let arg_ty = arg_tys[index];
+                            let arg_ty = arg_ty.subst(fcx.tcx(), &fcx.inh.param_env.free_substs);
+                            AdtField {
+                                ty: arg_ty,
+                                span: arg.ty.span
+                            }
+                        }).collect()
+                    }
+                }
+                ast::TupleVariantKind(_) => {
+                    AdtVariant {
+                        fields: Vec::new()
+                    }
+                }
+                ast::StructVariantKind(ref struct_def) => {
+                    struct_variant(fcx, &**struct_def)
+                }
+            }
+        })
+        .collect()
+}
+
 ///////////////////////////////////////////////////////////////////////////
 // Special drop trait checking
 

src/test/compile-fail/regions-enum-not-wf.rs

@@ -10,7 +10,6 @@
 
 // Various examples of structs whose fields are not well-formed.
 
-#![no_std]
 #![allow(dead_code)]
 
 enum Ref1<'a, T> { //~ ERROR the parameter type `T` may not live long enough

src/test/compile-fail/unsized5.rs

@@ -12,25 +12,25 @@
 // Test `Sized?` types not allowed in fields (except the last one).
 
 struct S1<Sized? X> {
-    f1: X, //~ ERROR type `f1` is dynamically sized. dynamically sized types may only appear as the
+    f1: X, //~ ERROR `core::kinds::Sized` is not implemented
     f2: int,
 }
 struct S2<Sized? X> {
     f: int,
-    g: X, //~ ERROR type `g` is dynamically sized. dynamically sized types may only appear as the ty
+    g: X, //~ ERROR `core::kinds::Sized` is not implemented
     h: int,
 }
 struct S3 {
-    f: str, //~ ERROR type `f` is dynamically sized. dynamically sized types may only appear
+    f: str, //~ ERROR `core::kinds::Sized` is not implemented
     g: [uint]
 }
 struct S4 {
-    f: str, //~ ERROR type `f` is dynamically sized. dynamically sized types may only appear
+    f: str, //~ ERROR `core::kinds::Sized` is not implemented
     g: uint
 }
 enum E<Sized? X> {
-    V1(X, int), //~ERROR type `X` is dynamically sized. dynamically sized types may only appear as t
-    V2{f1: X, f: int}, //~ERROR type `f1` is dynamically sized. dynamically sized types may only app
+    V1(X, int), //~ERROR `core::kinds::Sized` is not implemented
+    V2{f1: X, f: int}, //~ERROR `core::kinds::Sized` is not implemented
 }
 
 pub fn main() {