Try without generics, use fn pointers instead

tests/ui/debuginfo/auxiliary/line-tables-only-helper.rs

@@ -1,22 +1,25 @@
 //@ compile-flags: -Cstrip=none -Cdebuginfo=line-tables-only
+use std::backtrace::Backtrace;
 
 #[no_mangle]
-pub fn baz<F>(mut cb: F, data: u32) where F: FnMut(u32) {
-    cb(data);
+pub fn baz(cb: fn(u32) -> Backtrace, data: u32) -> Backtrace {
+    cb(data)
 }
 
 #[no_mangle]
-pub fn bar<F>(cb: F, data: u32) where F: FnMut(u32) {
-    baz(cb, data);
+pub fn bar(cb: fn(u32) -> Backtrace, data: u32) -> Backtrace {
+    baz(cb, data)
 }
 
 #[no_mangle]
-pub fn foo<F>(cb: F, data: u32) where F: FnMut(u32) {
-    bar(cb, data);
+pub fn foo(cb: fn(u32) -> Backtrace, data: u32) -> Backtrace {
+    bar(cb, data)
+}
+
+fn helper(_x: u32) -> Backtrace {
+    Backtrace::capture()
 }
 
 pub fn capture_backtrace() -> std::backtrace::Backtrace {
-    let mut bt = None;
-    foo(|_| bt = Some(std::backtrace::Backtrace::capture()), 42);
-    bt.unwrap()
+    foo(helper, 42)
 }

tests/ui/debuginfo/backtrace-line-tables-only.rs

@@ -38,7 +38,7 @@ fn assert_contains(
 fn main() {
     std::env::set_var("RUST_BACKTRACE", "1");
     let backtrace = line_tables_only_helper::capture_backtrace();
-    assert_contains(&backtrace, "foo", "line-tables-only-helper.rs", 5);
-    assert_contains(&backtrace, "bar", "line-tables-only-helper.rs", 10);
-    assert_contains(&backtrace, "baz", "line-tables-only-helper.rs", 15);
+    assert_contains(&backtrace, "foo", "line-tables-only-helper.rs", 6);
+    assert_contains(&backtrace, "bar", "line-tables-only-helper.rs", 11);
+    assert_contains(&backtrace, "baz", "line-tables-only-helper.rs", 16);
 }