Lint against non-camelCase trait alias names

Type aliases are linted as such, so (unstable) trait aliases should be
treated the same way.

2 files changed, 18 insertions, 0 deletions

diff --git a/src/test/ui/traits/alias/style_lint.rs b/src/test/ui/traits/alias/style_lint.rs
new file mode 100644
index 00000000000..33be20054b5
--- /dev/null
+++ b/src/test/ui/traits/alias/style_lint.rs
@@ -0,0 +1,8 @@
+// check-pass
+
+#![feature(trait_alias)]
+
+trait Foo = std::fmt::Display + std::fmt::Debug;
+trait bar = std::fmt::Display + std::fmt::Debug; //~WARN trait alias `bar` should have an upper camel case name
+
+fn main() {}
diff --git a/src/test/ui/traits/alias/style_lint.stderr b/src/test/ui/traits/alias/style_lint.stderr
new file mode 100644
index 00000000000..91e2ea90eb9
--- /dev/null
+++ b/src/test/ui/traits/alias/style_lint.stderr
@@ -0,0 +1,10 @@
+warning: trait alias `bar` should have an upper camel case name
+  --> $DIR/style_lint.rs:6:7
+   |
+LL | trait bar = std::fmt::Display + std::fmt::Debug;
+   |       ^^^ help: convert the identifier to upper camel case: `Bar`
+   |
+   = note: `#[warn(non_camel_case_types)]` on by default
+
+warning: 1 warning emitted
+