rustdoc: When view source, macro-expanded items are not shown at when macro is called

[tesuji]

Try this: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_parse/parser/struct.Restrictions.html
(Note: The link of rustc API may die).

Click to view source [src] button, it will lead you to bitflag doc.

I expected to see this happen: The button should lead me to source code at call site:

rust/src/librustc_parse/parser/mod.rs

Lines 33 to 38 in 1841fb9

	bitflags::bitflags! {
	struct Restrictions: u8 {
	const STMT_EXPR = 1 << 0;
	const NO_STRUCT_LITERAL = 1 << 1;
	}
	}

[jyn514]

Duplicate of #39726