auto merge of #11185 : huonw/rust/doc-ignore, r=cmr

Currently any line starting with `#` is filtered from the output,
including line like `#[deriving]`; this patch makes it so lines are only
filtered when followed by a space similar to the current behaviour of
the tutorial/manual tester.

src/test/run-make/rustdoc-hidden-line/Makefile

@@ -0,0 +1,7 @@
+-include ../tools.mk
+
+all:
+	$(RUSTDOC) --test foo.rs
+	$(RUSTDOC) -w html -o $(TMPDIR)/doc foo.rs
+	cp verify.sh $(TMPDIR)
+	$(call RUN,verify.sh) $(TMPDIR)

src/test/run-make/rustdoc-hidden-line/foo.rs

@@ -0,0 +1,22 @@
+#[crate_id="foo#0.1"];
+
+/// The '# ' lines should be removed from the output, but the #[deriving] should be
+/// retained.
+///
+/// ```rust
+/// mod to_make_deriving_work { // FIXME #4913
+///
+/// # #[deriving(Eq)] // invisible
+/// # struct Foo; // invisible
+///
+/// #[deriving(Eq)] // Bar
+/// struct Bar(Foo);
+///
+/// fn test() {
+///     let x = Bar(Foo);
+///     assert!(x == x); // check that the derivings worked
+/// }
+///
+/// }
+/// ```
+pub fn foo() {}

src/test/run-make/rustdoc-hidden-line/verify.sh

@@ -0,0 +1,8 @@
+#!/bin/sh
+
+file="$1/doc/foo/fn.foo.html"
+
+grep -v 'invisible' $file &&
+grep '#\[deriving(Eq)\] // Bar' $file
+
+exit $?