Try to clean up some lints and enable more

I came across the unused_extern_crates lint, which is allow-by-default.
It is however part of the rust_2018_idioms lint group, which we are
already denying.

Anyway, this discovery led me down a linting rabbit hole.

There is the unused_import_braces lint which arguable lints against
something that rustfmt already deals with. Both the lint and rustfmt
deal with the braces in  "use test::{A};". Thus, this lint can just be
dropped.

The "unused" lint group includes "unused_must_use" and some other things
that sound helpful, so let's just switch to the more generic lint. This
found some unused_macro_rules in x11rb/src/tracing.rs, which need to be
allowed, so this lint can just be denied and not forbidden. But some of
the lints that we forbid are part of the "unused" group and #[deny]ing
something that was previously #[forbid]en is an error. Thus, I am
switching the order of these and move all the #[deny]s up.

Next, I thought that "unused_qualifications" should be part of "unused",
but it actually is not. The following code warns about the allows for
unused_extern_crates and unused_must_use, but not unused_qualifications,
so this is not part of the unused group. Same for unused_results.

    #![forbid(unused)]
    #![allow(unused_extern_crates)]
    #![allow(unused_must_use)]
    #![allow(unused_qualifications)]
    #![allow(unused_results)]

Signed-off-by: Uli Schlachter <[email protected]>

extract-generated-code-doc/src/main.rs

@@ -3,8 +3,7 @@
     trivial_numeric_casts,
     unsafe_code,
     unreachable_pub,
-    unused_import_braces,
-    unused_must_use,
+    unused,
     unused_qualifications
 )]
 #![forbid(unsafe_code)]

generator/src/main.rs

@@ -3,8 +3,7 @@
     trivial_numeric_casts,
     unsafe_code,
     unreachable_pub,
-    unused_import_braces,
-    unused_must_use,
+    unused,
     unused_qualifications
 )]
 #![forbid(unsafe_code)]

x11rb-async/src/lib.rs

@@ -41,6 +41,17 @@
 //! * `extra-traits`: Implement extra traits for X11 types. This improves the output of the `Debug`
 //!   impl and adds `PartialEq`, `Eq`, `PartialOrd`, `Ord`, and `Hash` where possible.
 
+// A list of lints that are only #![deny] and not the stronger #![forbid]. Each one has a comment
+// explaining why it gets the weaker treatment.
+#![deny(
+    // Contains unreachable_code and "?" generates an #[allow] for this
+    unused,
+    // #[derive] generates an #[allow] for this; not part of "unused"
+    unused_qualifications,
+    // Not everything in x11rb::protocol has doc comments
+    missing_docs,
+)]
+
 #![forbid(
     missing_copy_implementations,
     missing_debug_implementations,
@@ -50,20 +61,11 @@
     trivial_casts,
     trivial_numeric_casts,
     unreachable_pub,
-    unused_import_braces,
     unused_must_use,
     unused_results,
     clippy::cast_lossless,
     clippy::needless_pass_by_value,
 )]
-// A list of lints that are only #![deny] and not the stronger #![forbid]. Each one has a comment
-// explaining why it gets the weaker treatment.
-#![deny(
-    // #[derive] generates an #[allow] for this
-    unused_qualifications,
-    // Not everything in x11rb::protocol has doc comments
-    missing_docs,
-)]
 #![cfg_attr(not(feature = "allow-unsafe-code"), forbid(unsafe_code))]
 
 // -- Public Modules --

x11rb-protocol/src/lib.rs

@@ -40,6 +40,19 @@
 //! * `extra-traits`: Implement extra traits for types. This improves the output of the `Debug`
 //!   impl and adds `PartialEq`, `Eq`, `PartialOrd`, `Ord`, and `Hash` where possible.
 
+// A list of lints that are only #![deny] and not the stronger #![forbid]. Each one has a comment
+// explaining why it gets the weaker treatment.
+#![deny(
+    // Contains unreachable_code and "?" generates an #[allow] for this
+    unused,
+    // #[derive] generates an #[allow] for this; not part of "unused"
+    unused_qualifications,
+    // serde's Deserialize/Serialize impls add allows for this
+    rust_2018_idioms,
+    // Not everything in x11rb_protocol::protocol has doc comments
+    missing_docs,
+)]
+
 #![forbid(
     missing_copy_implementations,
     missing_debug_implementations,
@@ -49,22 +62,11 @@
     trivial_numeric_casts,
     unreachable_pub,
     unsafe_code,
-    unused_import_braces,
     unused_must_use,
     unused_results,
     clippy::cast_lossless,
     clippy::needless_pass_by_value,
 )]
-// A list of lints that are only #![deny] and not the stronger #![forbid]. Each one has a comment
-// explaining why it gets the weaker treatment.
-#![deny(
-    // #[derive] generates an #[allow] for this
-    unused_qualifications,
-    // serde's Deserialize/Serialize impls add allows for this
-    rust_2018_idioms,
-    // Not everything in x11rb_protocol::protocol has doc comments
-    missing_docs,
-)]
 #![no_std]
 
 // std crate imports

x11rb/src/lib.rs

@@ -120,6 +120,17 @@
 //! The [event_loop_integration](event_loop_integration/index.html) module contains some hints for
 //! integrating x11rb with an event loop as doc comments.
 
+// A list of lints that are only #![deny] and not the stronger #![forbid]. Each one has a comment
+// explaining why it gets the weaker treatment.
+#![deny(
+    // Contains unreachable_code and "?" generates an #[allow] for this
+    unused,
+    // #[derive] generates an #[allow] for this; not part of "unused"
+    unused_qualifications,
+    // Not everything in x11rb::protocol has doc comments
+    missing_docs,
+)]
+
 #![forbid(
     missing_copy_implementations,
     missing_debug_implementations,
@@ -129,20 +140,11 @@
     trivial_casts,
     trivial_numeric_casts,
     unreachable_pub,
-    unused_import_braces,
     unused_must_use,
     unused_results,
     clippy::cast_lossless,
     clippy::needless_pass_by_value,
 )]
-// A list of lints that are only #![deny] and not the stronger #![forbid]. Each one has a comment
-// explaining why it gets the weaker treatment.
-#![deny(
-    // #[derive] generates an #[allow] for this
-    unused_qualifications,
-    // Not everything in x11rb::protocol has doc comments
-    missing_docs,
-)]
 #![cfg_attr(not(feature = "allow-unsafe-code"), forbid(unsafe_code))]
 
 // Only contains documentation, but no "actual rust"

x11rb/src/tracing.rs

@@ -102,6 +102,7 @@ macro_rules! warning_span {
     ( $name:expr ) => { $crate::tracing::implementation::span!($crate::tracing::Level::Warn, $name, ) };
     ( $name:expr, $($fields:tt)* ) => { $crate::tracing::implementation::span!($crate::tracing::Level::Warn, $name, $($fields)*) };
 }
+#[allow(unused_macro_rules)]
 macro_rules! info_span {
     ( $name:expr ) => { $crate::tracing::implementation::span!($crate::tracing::Level::Info, $name, ) };
     ( $name:expr, $($fields:tt)* ) => { $crate::tracing::implementation::span!($crate::tracing::Level::Info, $name, $($fields)*) };
@@ -110,6 +111,7 @@ macro_rules! debug_span {
     ( $name:expr ) => { $crate::tracing::implementation::span!($crate::tracing::Level::Debug, $name, ) };
     ( $name:expr, $($fields:tt)* ) => { $crate::tracing::implementation::span!($crate::tracing::Level::Debug, $name, $($fields)*) };
 }
+#[allow(unused_macro_rules)]
 macro_rules! trace_span {
     ( $name:expr ) => { $crate::tracing::implementation::span!($crate::tracing::Level::Trace, $name, ) };
     ( $name:expr, $($fields:tt)* ) => { $crate::tracing::implementation::span!($crate::tracing::Level::Trace, $name, $($fields)*) };

xcbgen-rs/src/lib.rs

@@ -11,8 +11,7 @@
     trivial_numeric_casts,
     unsafe_code,
     unreachable_pub,
-    unused_import_braces,
-    unused_must_use,
+    unused,
     unused_qualifications,
     missing_copy_implementations,
     missing_debug_implementations,

xtrace-example/src/main.rs

@@ -36,17 +36,19 @@
 //! The code in `connection_inner` then handles decoding X11 packets, updating the state of the
 //! connection, and generating output via `println!`.
 
+#![deny(
+    // Contains unreachable_code and "?" generates an #[allow] for this
+    unused,
+    // #[derive] generates an #[allow] for this; not part of "unused"
+    unused_qualifications,
+)]
+
 #![forbid(
     missing_docs,
     rust_2018_idioms,
     trivial_casts,
     trivial_numeric_casts,
-    unused_import_braces,
-    unused_results
-)]
-#![deny(
-    // #[derive] generates an #[allow] for this
-    unused_qualifications,
+    unused_results,
 )]
 
 use smol::Async;