Bump MSRV to 1.49 as required by tokio. (#561)

.github/workflows/ci.yaml

@@ -16,7 +16,7 @@ jobs:
         rust:
           - stable
           - beta
-          - 1.46.0  # MSRV
+          - 1.49.0  # MSRV
 
     steps:
       - uses: actions/checkout@v2

CHANGELOG.md

@@ -5,6 +5,8 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Changed
+- MSRV bumped to 1.49
 
 ## [0.3.5] - 2021-07-26
 ### Fixed

README.md

@@ -119,7 +119,7 @@ For more details, see the [CONTRIBUTING.md file](https://github.com/bheisler/cri
 Criterion.<span></span>rs supports the last three stable minor releases of Rust. At time of
 writing, this means Rust 1.50 or later. Older versions may work, but are not guaranteed.
 
-Currently, the oldest version of Rust believed to work is 1.46. Future versions of Criterion.<span></span>rs may
+Currently, the oldest version of Rust believed to work is 1.49. Future versions of Criterion.<span></span>rs may
 break support for such old versions, and this will not be considered a breaking change. If you
 require Criterion.<span></span>rs to work on old versions of Rust, you will need to stick to a
 specific patch version of Criterion.<span></span>rs.

plot/src/lib.rs

@@ -443,7 +443,7 @@ impl Figure {
 
         s.push_str(&format!(
             "set output '{}'\n",
-            self.output.display().to_string().replace("'", "''")
+            self.output.display().to_string().replace('\'', "''")
         ));
 
         if let Some(width) = self.box_width {

src/connection.rs

@@ -71,8 +71,9 @@ impl InnerConnection {
         // read the runner-hello
         let mut hello_buf = [0u8; RUNNER_HELLO_SIZE];
         socket.read_exact(&mut hello_buf)?;
-        assert!(
-            !(&hello_buf[0..RUNNER_MAGIC_NUMBER.len()] != RUNNER_MAGIC_NUMBER.as_bytes()),
+        assert_eq!(
+            &hello_buf[0..RUNNER_MAGIC_NUMBER.len()],
+            RUNNER_MAGIC_NUMBER.as_bytes(),
             "Not connected to cargo-criterion."
         );
 

src/plot/gnuplot_backend/mod.rs

@@ -26,7 +26,7 @@ use super::{PlotContext, PlotData, Plotter};
 use crate::format;
 
 fn gnuplot_escape(string: &str) -> String {
-    string.replace("_", "\\_").replace("'", "''")
+    string.replace('_', "\\_").replace('\'', "''")
 }
 
 static DEFAULT_FONT: &str = "Helvetica";

src/plot/plotters_backend/summary.rs

@@ -31,9 +31,9 @@ pub fn line_comparison(
     let (unit, series_data) = line_comparison_series_data(formatter, all_curves);
 
     let x_range =
-        plotters::data::fitting_range(series_data.iter().map(|(_, xs, _)| xs.iter()).flatten());
+        plotters::data::fitting_range(series_data.iter().flat_map(|(_, xs, _)| xs.iter()));
     let y_range =
-        plotters::data::fitting_range(series_data.iter().map(|(_, _, ys)| ys.iter()).flatten());
+        plotters::data::fitting_range(series_data.iter().flat_map(|(_, _, ys)| ys.iter()));
     let root_area = SVGBackend::new(&path, SIZE)
         .into_drawing_area()
         .titled(&format!("{}: Comparison", title), (DEFAULT_FONT, 20))
@@ -196,8 +196,7 @@ pub fn violin(
         formatter.scale_values(max, xs);
     });
 
-    let mut x_range =
-        plotters::data::fitting_range(kdes.iter().map(|(_, xs, _)| xs.iter()).flatten());
+    let mut x_range = plotters::data::fitting_range(kdes.iter().flat_map(|(_, xs, _)| xs.iter()));
     x_range.start = 0.0;
     let y_range = -0.5..all_curves.len() as f64 - 0.5;