Allow let bindings in const fn and constants

src/test/run-pass/ctfe/const-block-non-item-statement-3.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.
+
+#![feature(const_let)]
+
+type Array = [u32; {  let x = 2; 5 }];
+
+pub fn main() {}

src/test/run-pass/ctfe/const-block-non-item-statement.rs

@@ -0,0 +1,17 @@
+// 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.
+
+#![feature(const_let)]
+
+enum Foo {
+    Bar = { let x = 1; 3 }
+}
+
+pub fn main() {}

src/test/run-pass/ctfe/const-fn-destructuring-arg.rs

@@ -0,0 +1,23 @@
+// 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.
+
+// test that certain things are disallowed in const fn signatures
+
+#![feature(const_fn, const_let)]
+
+// no destructuring
+const fn i((
+            a,
+            b
+           ): (u32, u32)) -> u32 {
+    a + b
+}
+
+fn main() {}

src/test/run-pass/ctfe/issue-37550.rs

@@ -0,0 +1,18 @@
+// Copyright 2017 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.
+
+#![feature(const_fn, const_let)]
+
+const fn x() {
+    let t = true;
+    let x = || t;
+}
+
+fn main() {}

src/test/run-pass/ctfe/locals-in-const-fn.rs

@@ -0,0 +1,45 @@
+// Copyright 2018 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.
+
+// https://github.com/rust-lang/rust/issues/48821
+
+#![feature(const_fn, const_let)]
+
+const fn foo(i: usize) -> usize {
+    let x = i;
+    x
+}
+
+static FOO: usize = foo(42);
+
+const fn bar(mut i: usize) -> usize {
+    i += 8;
+    let x = &i;
+    *x
+}
+
+static BAR: usize = bar(42);
+
+const fn boo(mut i: usize) -> usize {
+    {
+        let mut x = i;
+        x += 10;
+        i = x;
+    }
+    i
+}
+
+static BOO: usize = boo(42);
+
+fn main() {
+    assert!(FOO == 42);
+    assert!(BAR == 50);
+    assert!(BOO == 52);
+}

src/test/ui/feature-gate-const_let.rs

@@ -0,0 +1,20 @@
+// Copyright 2018 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.
+
+// Test use of const let without feature gate.
+
+#![feature(const_fn)]
+
+const fn foo() -> usize {
+    let x = 42; //~ ERROR blocks in constant functions are limited to items and tail expressions
+    42
+}
+
+fn main() {}

src/test/ui/feature-gate-const_let.stderr

@@ -0,0 +1,9 @@
+error[E0016]: blocks in constant functions are limited to items and tail expressions
+  --> $DIR/feature-gate-const_let.rs:16:13
+   |
+LL |     let x = 42; //~ ERROR blocks in constant functions are limited to items and tail expressions
+   |             ^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0016`.