Add E0744 for control flow in consts

[rust.git] / src / librustc_passes / error_codes.rs

diff --git a/src/librustc_passes/error_codes.rs b/src/librustc_passes/error_codes.rs
index a2626617afec33f880c11b431a50a54d5d40e730..3f5b0dcab74e0a67271ad76c6040bc6c0020ff83 100644 (file)
--- a/src/librustc_passes/error_codes.rs
+++ b/src/librustc_passes/error_codes.rs
@@ -552,6 +552,30 @@ trait Foo {
 ```
 "##,
 
+E0666: r##"
+`impl Trait` types cannot appear nested in the
+generic arguments of other `impl Trait` types.
+
+Example of erroneous code:
+
+```compile_fail,E0666
+trait MyGenericTrait<T> {}
+trait MyInnerTrait {}
+
+fn foo(bar: impl MyGenericTrait<impl MyInnerTrait>) {}
+```
+
+Type parameters for `impl Trait` types must be
+explicitly defined as named generic parameters:
+
+```
+trait MyGenericTrait<T> {}
+trait MyInnerTrait {}
+
+fn foo<T: MyInnerTrait>(bar: impl MyGenericTrait<T>) {}
+```
+"##,
+
 E0695: r##"
 A `break` statement without a label appeared inside a labeled block.
 
@@ -602,10 +626,31 @@ async fn foo() {}
 Switch to the Rust 2018 edition to use `async fn`.
 "##,
 
+E0744: r##"
+Control-flow expressions are not allowed inside a const context.
+
+At the moment, `if` and `match`, as well as the looping constructs `for`,
+`while`, and `loop`, are forbidden inside a `const`, `static`, or `const fn`.
+
+```compile_fail,E0744
+const _: {
+    let mut x = 0;
+    loop {
+        x += 1;
+        if x == 4 {
+            break;
+        }
+    }
+
+    x
+};
+```
+
+"##,
+
 ;
     E0226, // only a single explicit lifetime bound is permitted
     E0472, // asm! is unsupported on this target
-    E0666, // nested `impl Trait` is illegal
     E0667, // `impl Trait` in projections
     E0696, // `continue` pointing to a labeled block
     E0706, // `async fn` in trait