Bump Rust toolchain channel from 1.77 to 1.78

Upgrade the version of Rust and related tooling from 1.77.0 to 1.78.0,
which was recently released[1].

The `io_error_more` gate is still applicable (verified based on the
corresponding GitHub issue and running the tests with the related code
removed).

No updates were necessary related to rust-fmt nor clippy.

--
1. https://blog.rust-lang.org/2024/05/02/Rust-1.78.0.html

CONTRIBUTING.md

@@ -110,7 +110,7 @@ To be able to contribute you need the following tooling:
 
 - [git] v2;
 - [Just] v1;
-- [Rust] and [Cargo] v1.77 (edition 2021) with [Clippy], [rustfmt] (see `rust-toolchain.toml`);
+- [Rust] and [Cargo] v1.78 (edition 2021) with [Clippy], [rustfmt] (see `rust-toolchain.toml`);
 - (Optional) [cargo-all-features] v1.7.0 or later;
 - (Optional) [cargo-deny] v0.14.2 or later;
 - (Optional) [cargo-mutants] v23.5.0 or later;

Containerfile.dev

@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: MIT-0
 
-FROM docker.io/rust:1.77.0-alpine3.19
+FROM docker.io/rust:1.78.0-alpine3.19
 
 RUN apk add --no-cache \
 	bash git just libressl-dev musl-dev perl

README.md

@@ -62,7 +62,7 @@ rm -fq file1 file2
 
 ## Build from Source
 
-To build from source you need [Rust] and [Cargo], v1.77 or higher, installed on your system. Then
+To build from source you need [Rust] and [Cargo], v1.78 or higher, installed on your system. Then
 run the command:
 
 ```shell

rust-toolchain.toml

@@ -1,7 +1,7 @@
 # Check out rustup at: https://rust-lang.github.io/rustup/index.html
 
 [toolchain]
-channel = "1.77.0"
+channel = "1.78.0"
 components = [
     "cargo",
     "clippy",

src/main.rs

@@ -2755,7 +2755,7 @@ mod rm {
         trace!("remove {entry}");
 
         if entry.is_dir() && !fs::is_empty(&entry) {
-            // This case is handled explicitly because, as of Rust 1.77, the `io::ErrorKind` variant
+            // This case is handled explicitly because, as of Rust 1.78, the `io::ErrorKind` variant
             // is still experimental (gate "io_error_more") and so would result in an unknown error.
             // This implementation leaves a possibility for a TOCTOU issue, but this will be handled
             // safely as `std::fs::remove_dir` doesn't remove non-empty directories.