Refactor `ty_infer` and `re_infer`

4 files changed, 40 insertions, 38 deletions

diff --git a/src/librustc_typeck/astconv.rs b/src/librustc_typeck/astconv.rs
index 349c4e608c2..63d9f0920cc 100644
--- a/src/librustc_typeck/astconv.rs
+++ b/src/librustc_typeck/astconv.rs
@@ -49,19 +49,17 @@ pub trait AstConv<'gcx, 'tcx> {
                                  -> &'tcx ty::GenericPredicates<'tcx>;
 
     /// Returns the lifetime to use when a lifetime is omitted (and not elided).
-    fn re_infer(&self, span: Span, _def: Option<&ty::GenericParamDef>)
+    fn re_infer(
+        &self,
+        param: Option<&ty::GenericParamDef>,
+        span: Span,
+    )
                 -> Option<ty::Region<'tcx>>;
 
     /// Returns the type to use when a type is omitted.
-    fn ty_infer(&self, span: Span) -> Ty<'tcx>;
+    fn ty_infer(&self, param: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx>;
 
-    /// Same as `ty_infer`, but with a known type parameter definition.
-    fn ty_infer_for_def(&self,
-                        _def: &ty::GenericParamDef,
-                        span: Span) -> Ty<'tcx> {
-        self.ty_infer(span)
-    }
-    /// What const should we use when a const is omitted?
+    /// Returns the const to use when a const is omitted.
     fn ct_infer(
         &self,
         ty: Ty<'tcx>,
@@ -163,7 +161,7 @@ impl<'o, 'gcx: 'tcx, 'tcx> dyn AstConv<'gcx, 'tcx> + 'o {
             }
 
             None => {
-                self.re_infer(lifetime.span, def)
+                self.re_infer(def, lifetime.span)
                     .unwrap_or_else(|| {
                         // This indicates an illegal lifetime
                         // elision. `resolve_lifetime` should have
@@ -701,11 +699,12 @@ impl<'o, 'gcx: 'tcx, 'tcx> dyn AstConv<'gcx, 'tcx> + 'o {
                             }
                         } else if infer_args {
                             // No type parameters were provided, we can infer all.
-                            if !default_needs_object_self(param) {
-                                self.ty_infer_for_def(param, span).into()
+                            let param = if !default_needs_object_self(param) {
+                                Some(param)
                             } else {
-                                self.ty_infer(span).into()
-                            }
+                                None
+                            };
+                            self.ty_infer(param, span).into()
                         } else {
                             // We've already errored above about the mismatch.
                             tcx.types.err.into()
@@ -1440,7 +1439,7 @@ impl<'o, 'gcx: 'tcx, 'tcx> dyn AstConv<'gcx, 'tcx> + 'o {
                 if tcx.named_region(lifetime.hir_id).is_some() {
                     self.ast_region_to_region(lifetime, None)
                 } else {
-                    self.re_infer(span, None).unwrap_or_else(|| {
+                    self.re_infer(None, span).unwrap_or_else(|| {
                         span_err!(tcx.sess, span, E0228,
                             "the lifetime bound for this object type cannot be deduced \
                              from context; please supply an explicit bound");
@@ -2134,7 +2133,7 @@ impl<'o, 'gcx: 'tcx, 'tcx> dyn AstConv<'gcx, 'tcx> + 'o {
                 // values in a ExprKind::Closure, or as
                 // the type of local variables. Both of these cases are
                 // handled specially and will not descend into this routine.
-                self.ty_infer(ast_ty.span)
+                self.ty_infer(None, ast_ty.span)
             }
             hir::TyKind::CVarArgs(lt) => {
                 let va_list_did = match tcx.lang_items().va_list() {
diff --git a/src/librustc_typeck/check/closure.rs b/src/librustc_typeck/check/closure.rs
index 4427a83562e..b894fc8c83c 100644
--- a/src/librustc_typeck/check/closure.rs
+++ b/src/librustc_typeck/check/closure.rs
@@ -598,7 +598,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
         let supplied_arguments = decl.inputs.iter().map(|a| astconv.ast_ty_to_ty(a));
         let supplied_return = match decl.output {
             hir::Return(ref output) => astconv.ast_ty_to_ty(&output),
-            hir::DefaultReturn(_) => astconv.ty_infer(decl.output.span()),
+            hir::DefaultReturn(_) => astconv.ty_infer(None, decl.output.span()),
         };
 
         let result = ty::Binder::bind(self.tcx.mk_fn_sig(
diff --git a/src/librustc_typeck/check/mod.rs b/src/librustc_typeck/check/mod.rs
index acb0b73af88..0b558a20ed4 100644
--- a/src/librustc_typeck/check/mod.rs
+++ b/src/librustc_typeck/check/mod.rs
@@ -1939,8 +1939,11 @@ impl<'a, 'gcx, 'tcx> AstConv<'gcx, 'tcx> for FnCtxt<'a, 'gcx, 'tcx> {
         })
     }
 
-    fn re_infer(&self, span: Span, def: Option<&ty::GenericParamDef>)
-                -> Option<ty::Region<'tcx>> {
+    fn re_infer(
+        &self,
+        def: Option<&ty::GenericParamDef>,
+        span: Span,
+    ) -> Option<ty::Region<'tcx>> {
         let v = match def {
             Some(def) => infer::EarlyBoundRegion(span, def.name),
             None => infer::MiscVariable(span)
@@ -1948,18 +1951,20 @@ impl<'a, 'gcx, 'tcx> AstConv<'gcx, 'tcx> for FnCtxt<'a, 'gcx, 'tcx> {
         Some(self.next_region_var(v))
     }
 
-    fn ty_infer(&self, span: Span) -> Ty<'tcx> {
-        self.next_ty_var(TypeVariableOrigin {
-            kind: TypeVariableOriginKind::TypeInference,
-            span,
-        })
+    fn ty_infer(&self, param: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> {
+        if let Some(param) = param {
+            if let UnpackedKind::Type(ty) = self.var_for_def(span, param).unpack() {
+                return ty;
+            }
+            unreachable!()
+        } else {
+            self.next_ty_var(TypeVariableOrigin {
+                kind: TypeVariableOriginKind::TypeInference,
+                span,
+            })
+        }
     }
 
-    fn ty_infer_for_def(&self,
-                        ty_param_def: &ty::GenericParamDef,
-                        span: Span) -> Ty<'tcx> {
-        if let UnpackedKind::Type(ty) = self.var_for_def(span, ty_param_def).unpack() {
-            return ty;
     fn ct_infer(
         &self,
         ty: Ty<'tcx>,
@@ -1977,7 +1982,6 @@ impl<'a, 'gcx, 'tcx> AstConv<'gcx, 'tcx> for FnCtxt<'a, 'gcx, 'tcx> {
                 span,
             })
         }
-        unreachable!()
     }
 
     fn projected_ty_from_poly_trait_ref(&self,
@@ -5463,7 +5467,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
             |substs, param, infer_args| {
                 match param.kind {
                     GenericParamDefKind::Lifetime => {
-                        self.re_infer(span, Some(param)).unwrap().into()
+                        self.re_infer(Some(param), span).unwrap().into()
                     }
                     GenericParamDefKind::Type { has_default, .. } => {
                         if !infer_args && has_default {
diff --git a/src/librustc_typeck/collect.rs b/src/librustc_typeck/collect.rs
index 64b92687cfe..8b770096cad 100644
--- a/src/librustc_typeck/collect.rs
+++ b/src/librustc_typeck/collect.rs
@@ -186,18 +186,17 @@ impl<'a, 'tcx> AstConv<'tcx, 'tcx> for ItemCtxt<'a, 'tcx> {
 
     fn re_infer(
         &self,
-        _span: Span,
-        _def: Option<&ty::GenericParamDef>,
+        _: Option<&ty::GenericParamDef>,
+        _: Span,
     ) -> Option<ty::Region<'tcx>> {
         None
     }
 
-    fn ty_infer(&self, span: Span) -> Ty<'tcx> {
-        struct_span_err!(
-            self.tcx().sess,
+    fn ty_infer(&self, _: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> {
+        self.tcx().sess.struct_span_err_with_code(
             span,
-            E0121,
-            "the type placeholder `_` is not allowed within types on item signatures"
+            "the type placeholder `_` is not allowed within types on item signatures",
+            DiagnosticId::Error("E0121".into()),
         ).span_label(span, "not allowed in type signatures")
          .emit();