[egui] Enable a bunch of clippy warnings

egui/src/containers/area.rs

@@ -160,6 +160,7 @@ impl Prepared {
         )
     }
 
+    #[allow(clippy::needless_pass_by_value)] // intentional to swallow up `content_ui`.
     pub(crate) fn end(self, ctx: &Arc<Context>, content_ui: Ui) -> Response {
         let Prepared {
             layer_id,

egui/src/containers/window.rs

@@ -295,7 +295,7 @@ impl<'open> Window<'open> {
             title_bar.ui(
                 &mut area_content_ui,
                 outer_rect,
-                content_response,
+                &content_response,
                 open,
                 &mut collapsing,
                 collapsible,
@@ -659,7 +659,7 @@ impl TitleBar {
         mut self,
         ui: &mut Ui,
         outer_rect: Rect,
-        content_response: Option<Response>,
+        content_response: &Option<Response>,
         open: Option<&mut bool>,
         collapsing: &mut collapsing_header::State,
         collapsible: bool,

egui/src/lib.rs

@@ -38,20 +38,34 @@
 #![cfg_attr(not(debug_assertions), deny(warnings))] // Forbid warnings in release builds
 #![warn(
     clippy::all,
+    clippy::await_holding_lock,
     clippy::dbg_macro,
     clippy::doc_markdown,
     clippy::empty_enum,
     clippy::enum_glob_use,
+    clippy::exit,
     clippy::filter_map_next,
     clippy::fn_params_excessive_bools,
+    clippy::if_let_mutex,
     clippy::imprecise_flops,
+    clippy::inefficient_to_string,
+    clippy::linkedlist,
     clippy::lossy_float_literal,
+    clippy::macro_use_imports,
+    clippy::match_on_vec_items,
+    clippy::match_wildcard_for_single_variants,
     clippy::mem_forget,
+    clippy::mismatched_target_os,
     clippy::needless_borrow,
     clippy::needless_continue,
+    clippy::needless_pass_by_value,
+    clippy::option_option,
     clippy::pub_enum_variant_names,
     clippy::rest_pat_in_fully_bound_structs,
     clippy::todo,
+    clippy::unimplemented,
+    clippy::unnested_or_patterns,
+    clippy::verbose_file_reads,
     future_incompatible,
     nonstandard_style,
     rust_2018_idioms

egui/src/widgets/drag_value.rs

@@ -1,3 +1,5 @@
+#![allow(clippy::needless_pass_by_value)] // False positives with `impl ToString`
+
 use std::ops::RangeInclusive;
 
 use crate::{paint::*, *};

example_web/src/example_app.rs

@@ -51,7 +51,6 @@ impl egui::app::App for ExampleApp {
             if let Ok(result) = receiver.try_recv() {
                 self.in_progress = None;
                 self.result = Some(result.map(Resource::from_response));
-            } else {
             }
         }