Fix issue #20427

src/test/auxiliary/i8.rs

@@ -0,0 +1,13 @@
+// Copyright 2015 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.
+
+// A crate named after a built-in type.
+
+pub struct Test;

src/test/compile-fail/issue-20427.rs

@@ -0,0 +1,66 @@
+// Copyright 2015 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.
+
+// aux-build:i8.rs
+extern crate i8;
+use std::string as i16;
+static i32: i32 = 0;
+const i64: i64 = 0;
+fn u8(f32: f32) {}
+fn f<f64>(f64: f64) {}
+//~^ ERROR user-defined types or type parameters cannot shadow the primitive types
+type u16 = u16; //~ ERROR user-defined types or type parameters cannot shadow the primitive types
+enum u32 {} //~ ERROR user-defined types or type parameters cannot shadow the primitive types
+struct u64; //~ ERROR user-defined types or type parameters cannot shadow the primitive types
+trait bool {} //~ ERROR user-defined types or type parameters cannot shadow the primitive types
+
+mod char {
+    extern crate i8;
+    static i32_: i32 = 0;
+    const i64_: i64 = 0;
+    fn u8_(f32: f32) {}
+    fn f_<f64_>(f64: f64_) {}
+    type u16_ = u16;
+    enum u32_ {}
+    struct u64_;
+    trait bool_ {}
+    mod char_ {}
+
+    mod str {
+        use super::i8 as i8;
+        use super::i32_ as i32;
+        use super::i64_ as i64;
+        use super::u8_ as u8;
+        use super::f_ as f64;
+        use super::u16_ as u16;
+        //~^ ERROR user-defined types or type parameters cannot shadow the primitive types
+        use super::u32_ as u32;
+        //~^ ERROR user-defined types or type parameters cannot shadow the primitive types
+        use super::u64_ as u64;
+        //~^ ERROR user-defined types or type parameters cannot shadow the primitive types
+        use super::bool_ as bool;
+        //~^ ERROR user-defined types or type parameters cannot shadow the primitive types
+        use super::char_ as char;
+    }
+}
+
+trait isize_ {
+    type isize; //~ ERROR user-defined types or type parameters cannot shadow the primitive types
+}
+
+fn usize<'usize>(usize: &'usize usize) -> &'usize usize { usize }
+
+fn main() {
+    let bool = true;
+    match bool {
+        str @ true => if str { i32 as i64 } else { 0 },
+        false => i64,
+    }
+}