fix non-idiomatic rust, arg.len error handling

taskchampion/xtask/src/main.rs

@@ -6,20 +6,23 @@
 use regex::Regex;
 use std::env;
 use std::fs::File;
-use std::io::{BufRead, BufReader};
-use std::io::{Seek, Write};
+use std::io::{BufRead, BufReader, Seek, Write};
 use std::path::{Path, PathBuf};
 
-/// The const MSRV_PATHS_REGEX in /xtask/main.rs is an array of tuples
-///  of the form (PATH, REGEX) where PATH and REGEX are literals where
-///  PATH is a file that updates the Minimum Supported Rust Version
-///  and REGEX is the pattern to find the appropriate line in the file
-
-// Increment length of array when adding tuples of (PATH, REGEX).
-const MSRV_PATH_REGEX: [(&str, &str); 1] = [(
-    "xtask/Cargo.toml",
-    r#"rust-version = "[0-9]+("|\.|[0-9])+""#,
-)];
+/// Tuples of the form (PATH, REGEX) where PATH and REGEX are literals where PATH is a file that
+/// conains the Minimum Supported Rust Version and REGEX is the pattern to find the appropriate
+/// line in the file. PATH is relative to the `taskchampion/` directory in the repo.
+const MSRV_PATH_REGEX: &[(&str, &str)] = &[
+    (
+        "../.github/workflows/checks.yml",
+        r#"toolchain: "[0-9.]+*" # MSRV"#,
+    ),
+    ("../.github/workflows/rust-tests.yml", r#""[0-9.]+" # MSRV"#),
+    (
+        "taskchampion/src/lib.rs",
+        r#"Rust version [0-9.]* and higher"#,
+    ),
+];
 
 pub fn main() -> anyhow::Result<()> {
     let manifest_dir = PathBuf::from(env::var("CARGO_MANIFEST_DIR")?);
@@ -54,9 +57,10 @@ fn codegen(workspace_dir: &Path) -> anyhow::Result<()> {
 /// Each line where the regex matches will have all values of the form `#.##` replaced with the given MSRV.
 fn msrv(args: Vec<String>, workspace_dir: &Path) -> anyhow::Result<()> {
     // check that (X.Y) argument is (mostly) valid:
-    if !args[2].chars().all(|c| c.is_numeric() || c == '.') {
+    if args.len() < 3 || !args[2].chars().all(|c| c.is_numeric() || c == '.') {
         anyhow::bail!("xtask: Invalid argument format. Xtask MSRV argument takes the form \"X.Y(y)\", where XYy are numbers. eg: `cargo run xtask MSRV 1.68`");
     }
+    let version_replacement_string = &args[2];
 
     // set regex for replacing version number only within the pattern found within a line
     let re_msrv_version = Regex::new(r"([0-9]+(\.|[0-9]+|))+")?;
@@ -65,28 +69,27 @@ fn msrv(args: Vec<String>, workspace_dir: &Path) -> anyhow::Result<()> {
     for msrv_file in MSRV_PATH_REGEX {
         let mut is_pattern_in_file = false;
 
-        let file_path = workspace_dir.join(msrv_file.0);
-        let path: &Path = Path::new(&file_path);
-        if !&path.exists() {
+        let path = workspace_dir.join(msrv_file.0);
+        let path = Path::new(&path);
+        if !path.exists() {
             anyhow::bail!("xtask: path does not exist {}", &path.display());
         };
 
-        let mut file: File = File::options().read(true).write(true).open(path)?;
+        let mut file = File::options().read(true).write(true).open(path)?;
         let reader = BufReader::new(&file);
 
         // set search string and the replacement string for version number content
         let re_msrv_pattern = Regex::new(msrv_file.1)?;
-        let version_replacement_string = &args[2];
 
         // for each line in file
         let mut file_string = String::new();
         for line in reader.lines() {
-            let line_ref = &line?;
+            let line = &line?;
 
             // if rust version pattern is found and is different, update it
-            if let Some(pattern_offset) = re_msrv_pattern.find(line_ref) {
+            if let Some(pattern_offset) = re_msrv_pattern.find(line) {
                 if !pattern_offset.as_str().contains(version_replacement_string) {
-                    file_string += &re_msrv_version.replace(line_ref, version_replacement_string);
+                    file_string += &re_msrv_version.replace(line, version_replacement_string);
 
                     file_string += "\n";
 
@@ -95,23 +98,18 @@ fn msrv(args: Vec<String>, workspace_dir: &Path) -> anyhow::Result<()> {
                 }
             }
 
-            file_string += line_ref;
+            file_string += line;
             file_string += "\n";
         }
 
         // if pattern was found and updated, write to disk
         if is_pattern_in_file {
             //  Set the file length to the file_string length
-            let _ = file.set_len(file_string.len() as u64);
+            file.set_len(file_string.len() as u64)?;
 
             //  set the cursor to the beginning of the file and write
-            let _ = file.seek(std::io::SeekFrom::Start(0));
-            let file_write_result = file.write(file_string.as_bytes());
-
-            // if error, print error messege and exit
-            if file_write_result.is_err() {
-                anyhow::bail!("xtask: unable to write file to disk: {}", &path.display());
-            }
+            file.seek(std::io::SeekFrom::Start(0))?;
+            file.write_all(file_string.as_bytes())?;
 
             // notify user this file was updated
             println!(