Check if merged attributes list is empty in expr Fixes #139373 In the example code, an [`UnrecognizedReprHint`](https://github.com/rust-lang/rust/blob/6b5ccfc87f59ab017032e430d4d358b4989735da/compiler/rustc_attr_parsing/src/attributes/repr.rs#L155) error is output, and the list of merged attributes becomes empty. This causes a [panic](https://github.com/rust-lang/rust/blob/6b5ccfc87f59ab017032e430d4d358b4989735da/compiler/rustc_ast_lowering/src/lib.rs#L618) to occur. So, it's necessary to check if merged attributes list is empty as other functions do. ref: https://github.com/rust-lang/rust/blob/6b5ccfc87f59ab017032e430d4d358b4989735da/compiler/rustc_ast_lowering/src/lib.rs#L896
UI Tests
This folder contains rustc's
UI tests.
Test Directives (Headers)
Typically, a UI test will have some test directives / headers which are special comments that tell compiletest how to build and interpret a test.
As part of an ongoing effort to rewrite compiletest
(see https://github.com/rust-lang/compiler-team/issues/536), a major
change proposal to change legacy compiletest-style headers // <directive>
to ui_test-style headers
//@ <directive> was accepted (see
https://github.com/rust-lang/compiler-team/issues/512.
An example directive is ignore-test. In legacy compiletest style, the header
would be written as
// ignore-test
but in ui_test style, the header would be written as
//@ ignore-test
compiletest is changed to accept only //@ directives for UI tests
(currently), and will reject and report an error if it encounters any
comments // <content> that may be parsed as a legacy compiletest-style
test header. To fix this, you should migrate to the ui_test-style header
//@ <content>.