eh: improve error and warning glyphs; move logger to new crate

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: I563b37a9f38f8dcec6dda7693ae45e826a6a6964

Cargo.lock

@@ -81,6 +81,7 @@ name = "eh"
 version = "0.1.3"
 dependencies = [
  "clap",
+ "eh-log",
  "regex",
  "tempfile",
  "thiserror",
@@ -88,6 +89,13 @@ dependencies = [
  "yansi",
 ]
 
+[[package]]
+name = "eh-log"
+version = "0.1.3"
+dependencies = [
+ "yansi",
+]
+
 [[package]]
 name = "errno"
 version = "0.3.14"

Cargo.toml

@@ -21,7 +21,8 @@ thiserror          = "2.0.17"
 walkdir            = "2.5.0"
 yansi              = "1.0.1"
 
-eh = { path = "./eh" }
+eh     = { path = "./eh" }
+eh-log = { path = "./crates/eh-log" }
 
 [profile.release]
 codegen-units = 1

crates/eh-log/Cargo.toml

@@ -0,0 +1,10 @@
+[package]
+name                   = "eh-log"
+description            = "Styled logging for eh"
+version.workspace      = true
+edition.workspace      = true
+authors.workspace      = true
+rust-version.workspace = true
+
+[dependencies]
+yansi.workspace = true

crates/eh-log/src/lib.rs

@@ -0,0 +1,31 @@
+use std::fmt;
+
+use yansi::Paint;
+
+pub fn info(args: fmt::Arguments) {
+  eprintln!("  {} {args}", "->".green().bold());
+}
+
+pub fn warn(args: fmt::Arguments) {
+  eprintln!("  {} {args}", "->".yellow().bold());
+}
+
+pub fn error(args: fmt::Arguments) {
+  eprintln!("  {} {args}", "!".red().bold());
+}
+
+pub fn hint(args: fmt::Arguments) {
+  eprintln!("  {} {args}", "~".yellow().dim());
+}
+
+#[macro_export]
+macro_rules! log_info  { ($($t:tt)*) => { $crate::info(format_args!($($t)*)) } }
+
+#[macro_export]
+macro_rules! log_warn  { ($($t:tt)*) => { $crate::warn(format_args!($($t)*)) } }
+
+#[macro_export]
+macro_rules! log_error { ($($t:tt)*) => { $crate::error(format_args!($($t)*)) } }
+
+#[macro_export]
+macro_rules! log_hint  { ($($t:tt)*) => { $crate::hint(format_args!($($t)*)) } }

eh/Cargo.toml

@@ -12,6 +12,7 @@ name       = "eh"
 
 [dependencies]
 clap.workspace               = true
+eh-log.workspace             = true
 regex.workspace              = true
 tempfile.workspace           = true
 thiserror.workspace          = true

eh/src/error.rs

@@ -4,46 +4,46 @@ use thiserror::Error;
 
 #[derive(Error, Debug)]
 pub enum EhError {
-  #[error("Nix command 'nix {command}' failed")]
+  #[error("nix {command} failed")]
   NixCommandFailed { command: String },
 
-  #[error("IO error: {0}")]
+  #[error("io: {0}")]
   Io(#[from] std::io::Error),
 
-  #[error("Regex error: {0}")]
+  #[error("regex: {0}")]
   Regex(#[from] regex::Error),
 
-  #[error("UTF-8 conversion error: {0}")]
+  #[error("utf-8 conversion: {0}")]
   Utf8(#[from] std::string::FromUtf8Error),
 
-  #[error("Hash extraction failed: could not parse hash from nix output")]
+  #[error("could not extract hash from nix output")]
   HashExtractionFailed { stderr: String },
 
-  #[error("No Nix files found in the current directory")]
+  #[error("no .nix files found in the current directory")]
   NoNixFilesFound,
 
-  #[error("Failed to fix hash in file: {path}")]
+  #[error("could not update hash in {path}")]
   HashFixFailed { path: String },
 
-  #[error("Process exited with code: {code}")]
+  #[error("process exited with code {code}")]
   ProcessExit { code: i32 },
 
-  #[error("Command execution failed: {command}")]
+  #[error("command '{command}' failed")]
   CommandFailed { command: String },
 
-  #[error("Command '{command}' timed out after {} seconds", duration.as_secs())]
+  #[error("nix {command} timed out after {} seconds", duration.as_secs())]
   Timeout {
     command:  String,
     duration: Duration,
   },
 
-  #[error("Pre-evaluation of '{expression}' failed: {stderr}")]
+  #[error("'{expression}' failed to evaluate: {stderr}")]
   PreEvalFailed {
     expression: String,
     stderr:     String,
   },
 
-  #[error("Invalid input: {input} - {reason}")]
+  #[error("invalid input '{input}': {reason}")]
   InvalidInput { input: String, reason: String },
 }
 
@@ -72,31 +72,25 @@ impl EhError {
   pub fn hint(&self) -> Option<&str> {
     match self {
       Self::NixCommandFailed { .. } => {
-        Some("Run with --show-trace for more details from nix")
+        Some("run with --show-trace for more details")
       },
       Self::PreEvalFailed { .. } => {
-        Some(
+        Some("check that the expression exists and is spelled correctly")
-          "Check that the expression exists in the flake and is spelled \
-           correctly",
-        )
       },
       Self::HashExtractionFailed { .. } => {
-        Some(
+        Some("nix reported a hash mismatch but the hash could not be parsed")
-          "The nix output contained a hash mismatch but the hash could not be \
-           parsed",
-        )
       },
       Self::NoNixFilesFound => {
-        Some("Run this command from a directory containing .nix files")
+        Some("run this command from a directory containing .nix files")
       },
       Self::Timeout { .. } => {
         Some(
-          "The command took too long; try a faster network or a smaller \
+          "the command took too long; try a faster network or a smaller \
            derivation",
         )
       },
       Self::InvalidInput { .. } => {
-        Some("Avoid shell metacharacters in nix arguments")
+        Some("avoid shell metacharacters in nix arguments")
       },
       Self::Io(_)
       | Self::Regex(_)
@@ -170,10 +164,7 @@ mod tests {
       command:  "build".into(),
       duration: Duration::from_secs(300),
     };
-    assert_eq!(
+    assert_eq!(err.to_string(), "nix build timed out after 300 seconds");
-      err.to_string(),
-      "Command 'build' timed out after 300 seconds"
-    );
 
     let err = EhError::PreEvalFailed {
       expression: "nixpkgs#hello".into(),
@@ -185,7 +176,7 @@ mod tests {
     let err = EhError::HashExtractionFailed {
       stderr: "some output".into(),
     };
-    assert!(err.to_string().contains("could not parse hash"));
+    assert!(err.to_string().contains("could not extract hash"));
   }
 
   #[test]

eh/src/main.rs

@@ -2,6 +2,7 @@ use std::{env, path::Path};
 
 use eh::{Cli, Command, CommandFactory, Parser};
 use error::Result;
+use yansi::Paint;
 
 mod build;
 mod command;
@@ -16,9 +17,9 @@ fn main() {
   match result {
     Ok(code) => std::process::exit(code),
     Err(e) => {
-      eprintln!("Error: {e}");
+      eh_log::log_error!("{e}");
       if let Some(hint) = e.hint() {
-        eprintln!("Hint: {hint}");
+        eh_log::log_hint!("{hint}");
       }
       std::process::exit(e.exit_code());
     },
@@ -41,14 +42,21 @@ fn dispatch_multicall(
 
   // Handle --help/-h/--version before forwarding to nix
   if rest.iter().any(|a| a == "--help" || a == "-h") {
-    eprintln!("{app_name}: shorthand for 'eh {subcommand}'");
+    eprintln!(
-    eprintln!("Usage: {app_name} [args...]");
+      "{}: shorthand for '{}'",
-    eprintln!("All arguments are forwarded to 'nix {subcommand}'.");
+      app_name.bold(),
+      format!("eh {subcommand}").bold()
+    );
+    eprintln!("  {} {app_name} [args...]", "usage:".green().bold());
+    eprintln!(
+      "  All arguments are forwarded to '{}'.",
+      format!("nix {subcommand}").dim()
+    );
     return Some(Ok(0));
   }
 
   if rest.iter().any(|a| a == "--version") {
-    eprintln!("{app_name} (eh {})", env!("CARGO_PKG_VERSION"));
+    eprintln!("{} (eh {})", app_name.bold(), env!("CARGO_PKG_VERSION"));
     return Some(Ok(0));
   }
 

eh/src/util.rs

@@ -4,6 +4,7 @@ use std::{
   sync::LazyLock,
 };
 
+use eh_log::{log_info, log_warn};
 use regex::Regex;
 use tempfile::NamedTempFile;
 use walkdir::WalkDir;
@@ -92,7 +93,7 @@ impl NixFileFixer for DefaultNixFileFixer {
     let mut fixed = false;
     for file_path in nix_files {
       if self.fix_hash_in_file(&file_path, old_hash, new_hash)? {
-        println!("Updated hash in {}", file_path.display());
+        log_info!("updated hash in {}", file_path.display().bold());
         fixed = true;
       }
     }
@@ -251,12 +252,11 @@ fn package_name(args: &[String]) -> &str {
 /// Print a retry message with consistent formatting.
 /// Format: `  -> <pkg>: <reason>, setting <ENV>=1`
 fn print_retry_msg(pkg: &str, reason: &str, env_var: &str) {
-  eprintln!(
+  log_warn!(
-    "  {} {}: {}, setting {}",
+    "{}: {}, setting {}",
-    "->".yellow().bold(),
     pkg.bold(),
     reason,
-    format!("{env_var}=1").bold(),
+    format!("{env_var}=1").bold()
   );
 }
 
@@ -316,14 +316,17 @@ fn pre_evaluate(args: &[String]) -> Result<RetryAction> {
     return Ok(action);
   }
 
-  // For other eval failures, warn but let the actual command handle the
+  // Non-retryable eval failure — fail fast with a clear message
-  // error with full streaming output rather than halting here.
+  // rather than running the full command and showing the same error again.
-  let err = EhError::PreEvalFailed {
+  let stderr_clean = stderr
+    .trim()
+    .strip_prefix("error:")
+    .unwrap_or(stderr.trim())
+    .trim();
+  Err(EhError::PreEvalFailed {
     expression: eval_arg.clone(),
-    stderr:     stderr.trim().to_string(),
+    stderr:     stderr_clean.to_string(),
-  };
+  })
-  eprintln!("  {} {}", "->".yellow().bold(), err,);
-  Ok(RetryAction::None)
 }
 
 pub fn validate_nix_args(args: &[String]) -> Result<()> {
@@ -398,10 +401,9 @@ pub fn handle_nix_with_retry(
     let old_hash = hash_extractor.extract_old_hash(&stderr);
     match fixer.fix_hash_in_files(old_hash.as_deref(), &new_hash) {
       Ok(true) => {
-        eprintln!(
+        log_info!(
-          "  {} {}: hash mismatch corrected in local files, rebuilding",
+          "{}: hash mismatch corrected in local files, rebuilding",
-          "->".green().bold(),
+          pkg.bold()
-          pkg.bold(),
         );
         let mut retry_cmd = NixCommand::new(subcommand)
           .print_build_logs(true)
@@ -416,10 +418,9 @@ pub fn handle_nix_with_retry(
         // No files were fixed, continue with normal error handling
       },
       Err(EhError::NoNixFilesFound) => {
-        eprintln!(
+        log_warn!(
-          "  {} {}: hash mismatch detected but no .nix files found to update",
+          "{}: hash mismatch detected but no .nix files found to update",
-          "->".yellow().bold(),
+          pkg.bold()
-          pkg.bold(),
         );
         // Continue with normal error handling
       },