From ac15a10b55580065320e48b29b6ff0ea36d8093a Mon Sep 17 00:00:00 2001
From: Michael Howell <michael@notriddle.com>
Date: Thu, 6 Feb 2025 15:38:28 -0700
Subject: [PATCH] just_underscores_and_digits: ignore empty ident

Empty idents come from error recovery, and should imply that a
better error has already been emitted.
---
 clippy_dev/src/fmt.rs                               |  9 +++++++--
 clippy_lints/src/non_expressive_names.rs            |  3 ++-
 .../non_expressive_names_error_recovery.fixed       |  8 ++++++++
 .../non_expressive_names_error_recovery.rs          |  8 ++++++++
 .../non_expressive_names_error_recovery.stderr      | 13 +++++++++++++
 5 files changed, 38 insertions(+), 3 deletions(-)
 create mode 100644 tests/ui/syntax-error-recovery/non_expressive_names_error_recovery.fixed
 create mode 100644 tests/ui/syntax-error-recovery/non_expressive_names_error_recovery.rs
 create mode 100644 tests/ui/syntax-error-recovery/non_expressive_names_error_recovery.stderr

diff --git a/clippy_dev/src/fmt.rs b/clippy_dev/src/fmt.rs
index 790dafa811f9..bdddf46a2cb1 100644
--- a/clippy_dev/src/fmt.rs
+++ b/clippy_dev/src/fmt.rs
@@ -290,8 +290,13 @@ fn run_rustfmt(context: &FmtContext) -> Result<(), Error> {
         .filter_map(|entry| {
             let entry = entry.expect("failed to find tests");
             let path = entry.path();
-
-            if path.extension() != Some("rs".as_ref()) || entry.file_name() == "ice-3891.rs" {
+            if path.extension() != Some("rs".as_ref())
+                || path
+                    .components()
+                    .nth_back(1)
+                    .is_some_and(|c| c.as_os_str() == "syntax-error-recovery")
+                || entry.file_name() == "ice-3891.rs"
+            {
                 None
             } else {
                 Some(entry.into_path().into_os_string())
diff --git a/clippy_lints/src/non_expressive_names.rs b/clippy_lints/src/non_expressive_names.rs
index 1a3b43cbb10a..c5873589b26f 100644
--- a/clippy_lints/src/non_expressive_names.rs
+++ b/clippy_lints/src/non_expressive_names.rs
@@ -208,7 +208,8 @@ impl SimilarNamesNameVisitor<'_, '_, '_> {
 
     fn check_ident(&mut self, ident: Ident) {
         let interned_name = ident.name.as_str();
-        if interned_name.chars().any(char::is_uppercase) {
+        // name can be empty if it comes from recovery
+        if interned_name.chars().any(char::is_uppercase) || interned_name.is_empty() {
             return;
         }
         if interned_name.chars().all(|c| c.is_ascii_digit() || c == '_') {
diff --git a/tests/ui/syntax-error-recovery/non_expressive_names_error_recovery.fixed b/tests/ui/syntax-error-recovery/non_expressive_names_error_recovery.fixed
new file mode 100644
index 000000000000..5e5821a140de
--- /dev/null
+++ b/tests/ui/syntax-error-recovery/non_expressive_names_error_recovery.fixed
@@ -0,0 +1,8 @@
+// https://github.com/rust-lang/rust-clippy/issues/12302
+use std::marker::PhantomData;
+
+pub struct Aa<T>(PhantomData<T>);
+
+fn aa(a: Aa<String>) {
+
+}
diff --git a/tests/ui/syntax-error-recovery/non_expressive_names_error_recovery.rs b/tests/ui/syntax-error-recovery/non_expressive_names_error_recovery.rs
new file mode 100644
index 000000000000..d6e1da0e0898
--- /dev/null
+++ b/tests/ui/syntax-error-recovery/non_expressive_names_error_recovery.rs
@@ -0,0 +1,8 @@
+// https://github.com/rust-lang/rust-clippy/issues/12302
+use std::marker::PhantomData;
+
+pub struct Aa<T>(PhantomData<T>);
+
+fn aa(a: Aa<String) {
+
+}
diff --git a/tests/ui/syntax-error-recovery/non_expressive_names_error_recovery.stderr b/tests/ui/syntax-error-recovery/non_expressive_names_error_recovery.stderr
new file mode 100644
index 000000000000..e334ca5241eb
--- /dev/null
+++ b/tests/ui/syntax-error-recovery/non_expressive_names_error_recovery.stderr
@@ -0,0 +1,13 @@
+error: expected one of `!`, `(`, `+`, `,`, `::`, `<`, or `>`, found `)`
+  --> tests/ui/syntax-error-recovery/non_expressive_names_error_recovery.rs:6:19
+   |
+LL | fn aa(a: Aa<String) {
+   |                   ^ expected one of 7 possible tokens
+   |
+help: you might have meant to end the type parameters here
+   |
+LL | fn aa(a: Aa<String>) {
+   |                   +
+
+error: aborting due to 1 previous error
+