Rollup merge of #69802 - matthiaskrgr:cl1ppy, r=Dylan-DPC

fix more clippy findings

* reduce references on match patterns (clippy::match_ref_pats)
* Use writeln!(fmt, "word") instead of write!(fmt, "word\n") (clippy::write_with_newline)
* libtest: remove redundant argument to writeln!() (clippy::writeln_empty_string)
* remove unneeded mutable references (cippy::unnecessary_mut_passed)
* libtest: declare variables as floats instead of casting them (clippy::unnecessary_cast)
* rustdoc: remove redundant static lifetimes (clippy::redundant_static_lifetimes)
* call .as_deref() instead of .as_ref().map(Deref::deref) (clippy::option_as_ref_deref)
* iterate over a maps values directly. (clippy::for_kv_map)
* rustdoc: simplify boolean condition (clippy::nonminimal_bool)
* Use ?-operator in more places (clippy::question_mark, had some false negatives fixed recently)
* rustdoc: Use .any(p) instead of find(p).is_some(). (clippy::search_is_some)
* rustdoc: don't call into_iter() on iterator. (clippy::identity_conversion)

Author: Centril

src/libcore/str/pattern.rs

@@ -365,11 +365,7 @@ unsafe impl<'a> ReverseSearcher<'a> for CharSearcher<'a> {
         let haystack = self.haystack.as_bytes();
         loop {
             // get the haystack up to but not including the last character searched
-            let bytes = if let Some(slice) = haystack.get(self.finger..self.finger_back) {
-                slice
-            } else {
-                return None;
-            };
+            let bytes = haystack.get(self.finger..self.finger_back)?;
             // the last byte of the utf8 encoded needle
             // SAFETY: we have an invariant that `utf8_size < 5`
             let last_byte = unsafe { *self.utf8_encoded.get_unchecked(self.utf8_size - 1) };
@@ -575,11 +571,12 @@ macro_rules! pattern_methods {
 
         #[inline]
         fn is_suffix_of(self, haystack: &'a str) -> bool
-            where $t: ReverseSearcher<'a>
+        where
+            $t: ReverseSearcher<'a>,
         {
             ($pmap)(self).is_suffix_of(haystack)
         }
-    }
+    };
 }
 
 macro_rules! searcher_methods {
@@ -614,7 +611,7 @@ macro_rules! searcher_methods {
         fn next_reject_back(&mut self) -> Option<(usize, usize)> {
             self.0.next_reject_back()
         }
-    }
+    };
 }
 
 /////////////////////////////////////////////////////////////////////////////

src/librustc/hir/map/mod.rs

@@ -298,7 +298,7 @@ impl<'hir> Map<'hir> {
     }
 
     pub fn def_kind(&self, hir_id: HirId) -> Option<DefKind> {
-        let node = if let Some(node) = self.find(hir_id) { node } else { return None };
+        let node = self.find(hir_id)?;
 
         Some(match node {
             Node::Item(item) => match item.kind {

src/librustc/ty/util.rs

@@ -346,12 +346,7 @@ impl<'tcx> TyCtxt<'tcx> {
         adt_did: DefId,
         validate: &mut dyn FnMut(Self, DefId) -> Result<(), ErrorReported>,
     ) -> Option<ty::Destructor> {
-        let drop_trait = if let Some(def_id) = self.lang_items().drop_trait() {
-            def_id
-        } else {
-            return None;
-        };
-
+        let drop_trait = self.lang_items().drop_trait()?;
         self.ensure().coherent_trait(drop_trait);
 
         let mut dtor_did = None;

src/librustc_driver/lib.rs

@@ -1124,12 +1124,7 @@ fn extra_compiler_flags() -> Option<(Vec<String>, bool)> {
         return None;
     }
 
-    let matches = if let Some(matches) = handle_options(&args) {
-        matches
-    } else {
-        return None;
-    };
-
+    let matches = handle_options(&args)?;
     let mut result = Vec::new();
     let mut excluded_cargo_defaults = false;
     for flag in ICE_REPORT_COMPILER_FLAGS {

src/librustc_infer/traits/auto_trait.rs

@@ -113,7 +113,7 @@ impl<'tcx> AutoTraitFinder<'tcx> {
             return AutoTraitResult::ExplicitImpl;
         }
 
-        return tcx.infer_ctxt().enter(|mut infcx| {
+        return tcx.infer_ctxt().enter(|infcx| {
             let mut fresh_preds = FxHashSet::default();
 
             // Due to the way projections are handled by SelectionContext, we need to run
@@ -164,7 +164,7 @@ impl<'tcx> AutoTraitFinder<'tcx> {
 
             let (full_env, full_user_env) = self
                 .evaluate_predicates(
-                    &mut infcx,
+                    &infcx,
                     trait_did,
                     ty,
                     new_env,

src/librustc_infer/traits/specialize/mod.rs

@@ -413,12 +413,7 @@ pub(super) fn specialization_graph_provider(
 fn to_pretty_impl_header(tcx: TyCtxt<'_>, impl_def_id: DefId) -> Option<String> {
     use std::fmt::Write;
 
-    let trait_ref = if let Some(tr) = tcx.impl_trait_ref(impl_def_id) {
-        tr
-    } else {
-        return None;
-    };
-
+    let trait_ref = tcx.impl_trait_ref(impl_def_id)?;
     let mut w = "impl".to_owned();
 
     let substs = InternalSubsts::identity_for_item(tcx, impl_def_id);

src/librustc_mir/transform/generator.rs

@@ -944,7 +944,7 @@ fn create_generator_drop_shim<'tcx>(
     // unrelated code from the resume part of the function
     simplify::remove_dead_blocks(&mut body);
 
-    dump_mir(tcx, None, "generator_drop", &0, source, &mut body, |_, _| Ok(()));
+    dump_mir(tcx, None, "generator_drop", &0, source, &body, |_, _| Ok(()));
 
     body
 }

src/librustc_mir/util/liveness.rs

@@ -293,7 +293,7 @@ fn dump_matched_mir_node<'tcx>(
         writeln!(file, "// MIR local liveness analysis for `{}`", node_path)?;
         writeln!(file, "// source = {:?}", source)?;
         writeln!(file, "// pass_name = {}", pass_name)?;
-        writeln!(file, "")?;
+        writeln!(file)?;
         write_mir_fn(tcx, source, body, &mut file, result)?;
         Ok(())
     });
@@ -316,7 +316,7 @@ pub fn write_mir_fn<'tcx>(
         write_basic_block(tcx, block, body, &mut |_, _| Ok(()), w)?;
         print(w, "   ", &result.outs)?;
         if block.index() + 1 != body.basic_blocks().len() {
-            writeln!(w, "")?;
+            writeln!(w)?;
         }
     }
 

src/librustc_mir/util/pretty.rs

@@ -134,7 +134,7 @@ fn dump_matched_mir_node<'tcx, F>(
         if let Some(ref layout) = body.generator_layout {
             writeln!(file, "// generator_layout = {:?}", layout)?;
         }
-        writeln!(file, "")?;
+        writeln!(file)?;
         extra_data(PassWhere::BeforeCFG, &mut file)?;
         write_user_type_annotations(body, &mut file)?;
         write_mir_fn(tcx, source, body, &mut extra_data, &mut file)?;
@@ -242,13 +242,13 @@ pub fn write_mir_pretty<'tcx>(
             first = false;
         } else {
             // Put empty lines between all items
-            writeln!(w, "")?;
+            writeln!(w)?;
         }
 
         write_mir_fn(tcx, MirSource::item(def_id), body, &mut |_, _| Ok(()), w)?;
 
         for (i, body) in tcx.promoted_mir(def_id).iter_enumerated() {
-            writeln!(w, "")?;
+            writeln!(w)?;
             let src = MirSource { instance: ty::InstanceDef::Item(def_id), promoted: Some(i) };
             write_mir_fn(tcx, src, body, &mut |_, _| Ok(()), w)?;
         }
@@ -271,7 +271,7 @@ where
         extra_data(PassWhere::BeforeBlock(block), w)?;
         write_basic_block(tcx, block, body, extra_data, w)?;
         if block.index() + 1 != body.basic_blocks().len() {
-            writeln!(w, "")?;
+            writeln!(w)?;
         }
     }
 
@@ -529,7 +529,7 @@ pub fn write_mir_intro<'tcx>(
     write_scope_tree(tcx, body, &scope_tree, w, OUTERMOST_SOURCE_SCOPE, 1)?;
 
     // Add an empty line before the first block is printed.
-    writeln!(w, "")?;
+    writeln!(w)?;
 
     Ok(())
 }

src/librustc_resolve/late/diagnostics.rs

@@ -1107,11 +1107,7 @@ impl<'tcx> LifetimeContext<'_, 'tcx> {
                 }
             };
 
-            match (
-                lifetime_names.len(),
-                lifetime_names.iter().next(),
-                snippet.as_ref().map(|s| s.as_str()),
-            ) {
+            match (lifetime_names.len(), lifetime_names.iter().next(), snippet.as_deref()) {
                 (1, Some(name), Some("&")) => {
                     suggest_existing(err, format!("&{} ", name));
                 }