Add test for the issue

tests/ui/proc-macro/auxiliary/issue-118809.rs

@@ -0,0 +1,20 @@
+// force-host
+// no-prefer-dynamic
+
+#![crate_type = "proc-macro"]
+
+extern crate proc_macro;
+use proc_macro::TokenStream;
+
+#[proc_macro_derive(Deserialize)]
+pub fn deserialize_derive(input: TokenStream) -> TokenStream {
+    "impl Build {
+        fn deserialize() -> Option<u64> {
+            let x: Option<u32> = Some(0);
+            Some(x? + 1)
+        }
+    }
+    "
+    .parse()
+    .unwrap()
+}

tests/ui/proc-macro/issue-118809.rs

@@ -0,0 +1,10 @@
+// aux-build: issue-118809.rs
+
+#[macro_use]
+extern crate issue_118809;
+
+#[derive(Deserialize)] //~ ERROR mismatched types [E0308]
+pub struct Build {
+}
+
+fn main() {}

tests/ui/proc-macro/issue-118809.stderr

@@ -0,0 +1,21 @@
+error[E0308]: mismatched types
+  --> $DIR/issue-118809.rs:6:10
+   |
+LL | #[derive(Deserialize)]
+   |          ^^^^^^^^^^^
+   |          |
+   |          expected `u64`, found `u32`
+   |          arguments to this enum variant are incorrect
+   |
+help: the type constructed contains `u32` due to the type of the argument passed
+  --> $DIR/issue-118809.rs:6:10
+   |
+LL | #[derive(Deserialize)]
+   |          ^^^^^^^^^^^ this argument influences the type of `Some`
+note: tuple variant defined here
+  --> $SRC_DIR/core/src/option.rs:LL:COL
+   = note: this error originates in the derive macro `Deserialize` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0308`.