Forbid use of generics with foreign functions. Closes #10353.

src/librustc/middle/typeck/collect.rs

@@ -552,6 +552,17 @@ pub fn ensure_no_ty_param_bounds(ccx: &CrateCtxt,
     }
 }
 
+fn ensure_generics_abi(ccx: &CrateCtxt,
+                       span: Span,
+                       abis: AbiSet,
+                       generics: &ast::Generics) {
+    if generics.ty_params.len() > 0 &&
+       !(abis.is_rust() || abis.is_intrinsic()) {
+        ccx.tcx.sess.span_err(span,
+                              "foreign functions may not use type parameters");
+    }
+}
+
 pub fn convert(ccx: &CrateCtxt, it: &ast::Item) {
     let tcx = ccx.tcx;
     debug!("convert: item {} with id {}", token::get_ident(it.ident), it.id);
@@ -566,7 +577,7 @@ pub fn convert(ccx: &CrateCtxt, it: &ast::Item) {
                                    tpt.ty,
                                    enum_definition.variants,
                                    generics);
-      }
+        },
         ast::ItemImpl(ref generics, ref opt_trait_ref, selfty, ref ms) => {
             let i_ty_generics = ty_generics(ccx, generics, 0);
             let selfty = ccx.to_ty(&ExplicitRscope, selfty);
@@ -609,7 +620,7 @@ pub fn convert(ccx: &CrateCtxt, it: &ast::Item) {
                          for a builtin kind");
                 }
             }
-      }
+        },
         ast::ItemTrait(ref generics, _, ref trait_methods) => {
             let trait_def = trait_def_of_item(ccx, it);
 
@@ -629,7 +640,7 @@ pub fn convert(ccx: &CrateCtxt, it: &ast::Item) {
             // convert_methods produces a tcache entry that is wrong for
             // static trait methods. This is somewhat unfortunate.
             ensure_trait_methods(ccx, it.id);
-      }
+        },
         ast::ItemStruct(struct_def, ref generics) => {
             ensure_no_ty_param_bounds(ccx, it.span, generics, "structure");
 
@@ -643,19 +654,24 @@ pub fn convert(ccx: &CrateCtxt, it: &ast::Item) {
             }
 
             convert_struct(ccx, struct_def, tpt, it.id);
-      }
+        },
         ast::ItemTy(_, ref generics) => {
             ensure_no_ty_param_bounds(ccx, it.span, generics, "type");
             let tpt = ty_of_item(ccx, it);
             write_ty_to_tcx(tcx, it.id, tpt.ty);
-      }
+        },
+        ast::ItemFn(_, _, abi, ref generics, _) => {
+            ensure_generics_abi(ccx, it.span, abi, generics);
+            let tpt = ty_of_item(ccx, it);
+            write_ty_to_tcx(tcx, it.id, tpt.ty);
+        },
         _ => {
             // This call populates the type cache with the converted type
             // of the item in passing. All we have to do here is to write
             // it into the node type table.
             let tpt = ty_of_item(ccx, it);
             write_ty_to_tcx(tcx, it.id, tpt.ty);
-      }
+        },
     }
 }
 

src/test/compile-fail/generic-extern.rs

@@ -0,0 +1,15 @@
+// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+extern "C" fn foo<T>() {}  //~ERROR foreign functions may not use type parameters
+
+fn main() {
+    let _ = foo::<int>;
+}