3 files changed, 20 insertions, 0 deletions
diff --git a/src/test/ui/parser/issue-100197-mut-let.fixed b/src/test/ui/parser/issue-100197-mut-let.fixed
new file mode 100644
index 00000000000..5a895622200
--- /dev/null
+++ b/src/test/ui/parser/issue-100197-mut-let.fixed
@@ -0,0 +1,6 @@
+// run-rustfix
+
+fn main() {
+    let mut _x = 123;
+    //~^ ERROR invalid variable declaration
+}
diff --git a/src/test/ui/parser/issue-100197-mut-let.rs b/src/test/ui/parser/issue-100197-mut-let.rs
new file mode 100644
index 00000000000..71103813a6e
--- /dev/null
+++ b/src/test/ui/parser/issue-100197-mut-let.rs
@@ -0,0 +1,6 @@
+// run-rustfix
+
+fn main() {
+    mut let _x = 123;
+    //~^ ERROR invalid variable declaration
+}
diff --git a/src/test/ui/parser/issue-100197-mut-let.stderr b/src/test/ui/parser/issue-100197-mut-let.stderr
new file mode 100644
index 00000000000..86658e4f39f
--- /dev/null
+++ b/src/test/ui/parser/issue-100197-mut-let.stderr
@@ -0,0 +1,8 @@
+error: invalid variable declaration
+  --> $DIR/issue-100197-mut-let.rs:4:5
+   |
+LL |     mut let _x = 123;
+   |     ^^^^^^^ help: switch the order of `mut` and `let`: `let mut`
+
+error: aborting due to previous error
+