Update MSRV and fix clippy warnings

azure-pipelines.yml

@@ -2,7 +2,7 @@ jobs:
  - template: default.yml@templates
    parameters:
      codecov_token: $(CODECOV_TOKEN_SECRET)
-     minrust: 1.46.0
+     minrust: 1.52.0
      env:
        RUST_BACKTRACE: 1
      setup:

src/bin/flamegraph.rs

@@ -261,7 +261,7 @@ impl<'a> Opt {
     #[cfg(feature = "nameattr")]
     fn set_func_frameattrs(&self, options: &mut Options) {
         if let Some(file) = &self.nameattr {
-            match FuncFrameAttrsMap::from_file(&file) {
+            match FuncFrameAttrsMap::from_file(file) {
                 Ok(m) => {
                     options.func_frameattrs = m;
                 }

src/collapse/perf.rs

@@ -586,15 +586,13 @@ fn with_module_fallback(module: &str, func: &str, pc: &str, include_addrs: bool)
     // output string is a bit longer than rawfunc but not much
     let mut res = String::with_capacity(func.len() + 12);
 
+    res.push('[');
+    res.push_str(func);
     if include_addrs {
-        res.push('[');
-        res.push_str(func);
         res.push_str(" <");
         res.push_str(pc);
         res.push_str(">]");
     } else {
-        res.push('[');
-        res.push_str(func);
         res.push(']');
     }
 

src/collapse/vtune.rs

@@ -122,9 +122,9 @@ impl From<Options> for Folder {
 
 impl Folder {
     fn line_parts<'a>(&self, line: &'a str) -> Option<(&'a str, &'a str, &'a str)> {
-        let mut line = if line.starts_with('"') {
+        let mut line = if let Some(line) = line.strip_prefix('"') {
             // The function name will be in quotes if it contains spaces.
-            line[1..].splitn(2, "\",")
+            line.splitn(2, "\",")
         } else {
             // We split on a string because we need to match the type of the other if branch.
             #[allow(clippy::single_char_pattern)]

src/flamegraph/attrs.rs

@@ -1,6 +1,6 @@
 use std::fs::File;
 use std::io::{self, BufRead, BufReader};
-use std::path::PathBuf;
+use std::path::Path;
 
 use ahash::AHashMap;
 use indexmap::map::Entry;
@@ -27,7 +27,7 @@ impl FuncFrameAttrsMap {
     ///
     /// Each line should consist of a function name, a tab (`\t`), and then a sequence of
     /// tab-separated `name=value` pairs.
-    pub fn from_file(path: &PathBuf) -> io::Result<FuncFrameAttrsMap> {
+    pub fn from_file(path: &Path) -> io::Result<FuncFrameAttrsMap> {
         let file = BufReader::new(File::open(path)?);
         FuncFrameAttrsMap::from_reader(file)
     }
@@ -158,8 +158,8 @@ impl<'a> Iterator for AttrIter<'a> {
             warn!("no value after \"=\" for extra attribute {}", name);
         }
 
-        let (value, rest) = if rest.starts_with('"') {
-            if let Some(eq) = rest[1..].find('"') {
+        let (value, rest) = if let Some(stripped_rest) = rest.strip_prefix('"') {
+            if let Some(eq) = stripped_rest.find('"') {
                 (&rest[1..=eq], &rest[eq + 1..])
             } else {
                 warn!("no end quote found for extra attribute {}", name);

src/flamegraph/color/palettes.rs

@@ -22,11 +22,7 @@ pub(super) mod java {
             }
         }
 
-        let java_prefix = if name.starts_with('L') {
-            &name[1..]
-        } else {
-            name
-        };
+        let java_prefix = name.strip_prefix('L').unwrap_or(name);
 
         if name.contains("::") || name.starts_with("-[") || name.starts_with("+[") {
             // C++ or Objective C

src/flamegraph/mod.rs

@@ -456,7 +456,7 @@ where
         error!("No stack counts found");
         // emit an error message SVG, for tools automating flamegraph use
         let imageheight = opt.font_size * 5;
-        svg::write_header(&mut svg, imageheight, &opt)?;
+        svg::write_header(&mut svg, imageheight, opt)?;
         svg::write_str(
             &mut svg,
             &mut buffer,
@@ -493,7 +493,7 @@ where
 
     // draw canvas, and embed interactive JavaScript program
     let imageheight = ((depthmax + 1) * opt.frame_height) + opt.ypad1() + opt.ypad2();
-    svg::write_header(&mut svg, imageheight, &opt)?;
+    svg::write_header(&mut svg, imageheight, opt)?;
 
     let (bgcolor1, bgcolor2) = color::bgcolor_for(opt.bgcolors, opt.colors);
     let style_options = StyleOptions {
@@ -502,7 +502,7 @@ where
         bgcolor2,
     };
 
-    svg::write_prelude(&mut svg, &style_options, &opt)?;
+    svg::write_prelude(&mut svg, &style_options, opt)?;
 
     // Used when picking color parameters at random, when no option determines how to pick these
     // parameters. We instanciate it here because it may be called once for each iteration in the
@@ -573,7 +573,7 @@ where
             write!(buffer, "all ({} {}, 100%)", samples_txt, opt.count_name)
         } else {
             let pct = (100 * samples) as f64 / (timemax as f64 * opt.factor);
-            let function = deannotate(&frame.location.function);
+            let function = deannotate(frame.location.function);
             match frame.delta {
                 None => write!(
                     buffer,
@@ -634,7 +634,7 @@ where
             let colors = opt.colors;
             let hash = opt.hash;
             let deterministic = opt.deterministic;
-            palette_map.find_color_for(&frame.location.function, |name| {
+            palette_map.find_color_for(frame.location.function, |name| {
                 color::color(colors, hash, deterministic, name, &mut thread_rng)
             })
         } else {
@@ -653,7 +653,7 @@ where
             .trunc() as usize;
         let text: svg::TextArgument<'_> = if fitchars >= 3 {
             // room for one char plus two dots
-            let f = deannotate(&frame.location.function);
+            let f = deannotate(frame.location.function);
 
             // TODO: use Unicode grapheme clusters instead
             if f.len() < fitchars {
@@ -718,11 +718,11 @@ fn write_container_start<'a, W: Write>(
     let mut has_href = false;
     if let Some(frame_attributes) = frame_attributes {
         if frame_attributes.attrs.contains_key("xlink:href") {
-            write_container_attributes(cache_a, &frame_attributes);
+            write_container_attributes(cache_a, frame_attributes);
             svg.write_event(&cache_a)?;
             has_href = true;
         } else {
-            write_container_attributes(cache_g, &frame_attributes);
+            write_container_attributes(cache_g, frame_attributes);
             svg.write_event(&cache_g)?;
         }
         if let Some(ref t) = frame_attributes.title {