Add new `useless_concat` lint (#13829)

Fixes #13793.

Interestingly enough, to actually check that the macro call has at least
two arguments, we need to use the rust lexer after getting the original
source code snippet.

changelog: Add new `useless_concat` lint

1 files changed, 1 insertions, 0 deletions

diff --git a/clippy_utils/src/paths.rs b/clippy_utils/src/paths.rs
index e5179e479cc..9d7f3086b05 100644
--- a/clippy_utils/src/paths.rs
+++ b/clippy_utils/src/paths.rs
@@ -129,6 +129,7 @@ path_macros! {
 // Paths in `core`/`alloc`/`std`. This should be avoided and cleaned up by adding diagnostic items.
 pub static ALIGN_OF: PathLookup = value_path!(core::mem::align_of);
 pub static CHAR_TO_DIGIT: PathLookup = value_path!(char::to_digit);
+pub static CONCAT: PathLookup = macro_path!(core::concat);
 pub static IO_ERROR_NEW: PathLookup = value_path!(std::io::Error::new);
 pub static IO_ERRORKIND_OTHER_CTOR: PathLookup = value_path!(std::io::ErrorKind::Other);
 pub static ITER_STEP: PathLookup = type_path!(core::iter::Step);