Add a regression test for issue-75801

Author: JohnTitor

src/test/ui/proc-macro/auxiliary/issue-75801.rs

@@ -0,0 +1,13 @@
+// force-host
+// no-prefer-dynamic
+
+#![crate_type = "proc-macro"]
+
+extern crate proc_macro;
+
+use proc_macro::TokenStream;
+
+#[proc_macro_attribute]
+pub fn foo(_args: TokenStream, item: TokenStream) -> TokenStream {
+    item
+}

src/test/ui/proc-macro/issue-75801.rs

@@ -0,0 +1,19 @@
+// aux-build: issue-75801.rs
+
+// Regression test for #75801.
+
+#[macro_use]
+extern crate issue_75801;
+
+macro_rules! foo {
+    ($arg:expr) => {
+        #[foo]
+        fn bar() {
+            let _bar: u32 = $arg;
+        }
+    };
+}
+
+foo!("baz"); //~ ERROR: mismatched types [E0308]
+
+fn main() {}

src/test/ui/proc-macro/issue-75801.stderr

@@ -0,0 +1,12 @@
+error[E0308]: mismatched types
+  --> $DIR/issue-75801.rs:17:6
+   |
+LL |             let _bar: u32 = $arg;
+   |                       --- expected due to this
+...
+LL | foo!("baz");
+   |      ^^^^^ expected `u32`, found `&str`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.