Fix false positives for implicit_return and empty_loop on macro expansion.

[daxpedda]

This PR only fixes implicit_return and empty_loop.
But I suspect this bug may affect a lot of other lints.

[flip1995]

LGTM! We already have a convenience function to check for macro expansions:

rust-clippy/clippy_lints/src/utils/mod.rs

Lines 73 to 76 in fc24fce

	/// Returns true if this `expn_info` was expanded by any macro.
	pub fn in_macro(span: Span) -> bool {
	span.ctxt().outer().expn_info().is_some()
	}

Please use this function instead of the macro_backtrace function.

[daxpedda]

Done.

[flip1995]

Thanks! There's currently something wrong with travis. I'll merge this as soon as travis works again.

[daxpedda]

Yeah: rust-lang/rust#57111.
Hopefully nightly will work tomorrow again.

[flip1995]

@bors r+

[bors]

📌 Commit 1979144 has been approved by flip1995

[bors]

⌛ Testing commit 1979144 with merge 71c5a0d...

[bors]

💔 Test failed - status-appveyor

[daxpedda]

😕 that's not me is it?
https://ci.appveyor.com/project/rust-lang-libs/rust-clippy/builds/21236656#L766

+error: type parameter `u32` should have a camel case name such as `U32`
+  --> $DIR/builtin-type-shadow.rs:12:8
+   |
+12 | fn foo<u32>(a: u32) -> u32 {
+   |        ^^^
+   |
+   = note: `-D non-camel-case-types` implied by `-D warnings`
+

[flip1995]

Oh yeah this is fixed in #3581

[flip1995]

@bors rollup

[flip1995]

Please run rustfmt

[daxpedda]

And here I was sure I didn't forget anything this time.
Thanks for being so meticulous.

[flip1995]

Thanks for being so meticulous.

That's not me, that's our CI 😄

@bors r+ Thanks!

[bors]

📌 Commit 2d96ef1 has been approved by flip1995

[bors]

⌛ Testing commit 2d96ef1 with merge 721f688...

[bors]

☀️ Test successful - status-appveyor, status-travis
Approved by: flip1995
Pushing 721f688 to master...