Suggest adding no_main for error[E0601] (#1113)

* Use duct to build/invoke cargo command

* Push command to args

* Ignore cargo tree stdout

* Suggest adding `no_main`

* Read one byte at a time to get the progress bar

* Refactor to separate method

* Update crates/build/src/lib.rs

Co-authored-by: Michael Müller <[email protected]>

* Detect term size

* Update suggestion and exit on error

* Update message

* Hardcode term size

* Hardcode term size

* Only detect term size on non windows OS

* Red

* Use term_size for windows

* use term_size as _;

---------

Co-authored-by: Michael Müller <[email protected]>

crates/build/Cargo.toml

@@ -19,6 +19,7 @@ blake2 = "0.10.6"
 cargo_metadata = "0.15.4"
 colored = "2.0.0"
 clap = { version = "4.2.7", features = ["derive", "env"] }
+duct = "0.13.6"
 heck = "0.4.0"
 hex = "0.4.3"
 impl-serde = "0.4.0"
@@ -31,6 +32,7 @@ semver = { version = "1.0.17", features = ["serde"] }
 serde = { version = "1", default-features = false, features = ["derive"] }
 serde_json = "1.0.96"
 tempfile = "3.5.0"
+term_size = "0.3.2"
 url = { version = "2.3.1", features = ["serde"] }
 wasm-opt = "0.112.0"
 which = "4.4.0"

crates/build/src/lib.rs

@@ -83,7 +83,9 @@ use parity_wasm::elements::{
 };
 use semver::Version;
 use std::{
+    collections::VecDeque,
     fs,
+    io,
     path::{
         Path,
         PathBuf,
@@ -291,9 +293,10 @@ fn exec_cargo_for_onchain_target(
             None
         };
 
-        util::invoke_cargo(command, &args, manifest_path.directory(), verbosity, env)?;
+        let cargo =
+            util::cargo_cmd(command, &args, manifest_path.directory(), verbosity, env);
 
-        Ok(())
+        invoke_cargo_and_scan_for_error(cargo)
     };
 
     if unstable_flags.original_manifest {
@@ -320,6 +323,51 @@ fn exec_cargo_for_onchain_target(
     Ok(())
 }
 
+/// Executes the supplied cargo command, reading the output and scanning for known errors.
+/// Writes the captured stderr back to stderr and maintains the cargo tty progress bar.
+fn invoke_cargo_and_scan_for_error(cargo: duct::Expression) -> Result<()> {
+    macro_rules! eprintln_red {
+        ($value:expr) => {{
+            use colored::Colorize as _;
+            ::std::eprintln!("{}", $value.bright_red().bold());
+        }};
+    }
+
+    let cargo = util::cargo_tty_output(cargo);
+
+    let missing_main_err = "error[E0601]".as_bytes();
+    let mut err_buf = VecDeque::with_capacity(missing_main_err.len());
+
+    let mut reader = cargo.stderr_to_stdout().reader()?;
+    let mut buffer = [0u8; 1];
+
+    loop {
+        let bytes_read = io::Read::read(&mut reader, &mut buffer)?;
+        for byte in buffer[0..bytes_read].iter() {
+            err_buf.push_back(*byte);
+            if err_buf.len() > missing_main_err.len() {
+                let byte = err_buf.pop_front().expect("buffer is not empty");
+                io::Write::write(&mut io::stderr(), &[byte])?;
+            }
+        }
+        if missing_main_err == err_buf.make_contiguous() {
+            eprintln_red!("\nExited with error: [E0601]");
+            eprintln_red!(
+                "Your contract must be annotated with the `no_main` attribute.\n"
+            );
+            eprintln_red!("Examples how to do this:");
+            eprintln_red!("   - `#![cfg_attr(not(feature = \"std\"), no_std, no_main)]`");
+            eprintln_red!("   - `#[no_main]`\n");
+            return Err(anyhow::anyhow!("missing `no_main` attribute"))
+        }
+        if bytes_read == 0 {
+            break
+        }
+        buffer = [0u8; 1];
+    }
+    Ok(())
+}
+
 /// Executes `cargo dylint` with the ink! linting driver that is built during
 /// the `build.rs`.
 ///
@@ -357,8 +405,15 @@ fn exec_cargo_dylint(crate_metadata: &CrateMetadata, verbosity: Verbosity) -> Re
             Ok(())
         })?
         .using_temp(|manifest_path| {
-            util::invoke_cargo("dylint", &args, manifest_path.directory(), verbosity, env)
-                .map(|_| ())
+            let cargo = util::cargo_cmd(
+                "dylint",
+                &args,
+                manifest_path.directory(),
+                verbosity,
+                env,
+            );
+            cargo.run()?;
+            Ok(())
         })?;
 
     Ok(())
@@ -548,7 +603,11 @@ fn assert_compatible_ink_dependencies(
 ) -> Result<()> {
     for dependency in ["parity-scale-codec", "scale-info"].iter() {
         let args = ["-i", dependency, "--duplicates"];
-        let _ = util::invoke_cargo("tree", args, manifest_path.directory(), verbosity, vec![])
+        let cargo =
+            util::cargo_cmd("tree", args, manifest_path.directory(), verbosity, vec![]);
+        cargo
+            .stdout_null()
+            .run()
             .with_context(|| {
                 format!(
                     "Mismatching versions of `{dependency}` were found!\n\

crates/build/src/metadata.rs

@@ -149,16 +149,17 @@ pub(crate) fn execute(
         network.append_to_args(&mut args);
         features.append_to_args(&mut args);
 
-        let stdout = util::invoke_cargo(
+        let cmd = util::cargo_cmd(
             "run",
             args,
             crate_metadata.manifest_path.directory(),
             verbosity,
             vec![],
-        )?;
+        );
+        let output = cmd.stdout_capture().run()?;
 
         let ink_meta: serde_json::Map<String, serde_json::Value> =
-            serde_json::from_slice(&stdout)?;
+            serde_json::from_slice(&output.stdout)?;
         let metadata = ContractMetadata::new(source, contract, user, ink_meta);
         {
             let mut metadata = metadata.clone();

crates/build/src/util/mod.rs

@@ -18,15 +18,13 @@
 pub mod tests;
 
 use crate::Verbosity;
-use anyhow::{
-    Context,
-    Result,
-};
+use anyhow::Result;
+use duct::Expression;
 use std::{
-    ffi::OsStr,
+    ffi::OsString,
     path::Path,
-    process::Command,
 };
+use term_size as _;
 
 // Returns the current Rust toolchain formatted by `<channel>-<target-triple>`.
 pub(crate) fn rust_toolchain() -> Result<String> {
@@ -36,75 +34,77 @@ pub(crate) fn rust_toolchain() -> Result<String> {
     Ok(toolchain)
 }
 
-/// Invokes `cargo` with the subcommand `command` and the supplied `args`.
+/// Builds an [`Expression`] for invoking `cargo`.
 ///
 /// In case `working_dir` is set, the command will be invoked with that folder
 /// as the working directory.
 ///
 /// In case `env` is given environment variables can be either set or unset:
 ///   * To _set_ push an item a la `("VAR_NAME", Some("VAR_VALUE"))` to the `env` vector.
 ///   * To _unset_ push an item a la `("VAR_NAME", None)` to the `env` vector.
-///
-/// If successful, returns the stdout bytes.
-pub fn invoke_cargo<I, S, P>(
+pub fn cargo_cmd<I, S, P>(
     command: &str,
     args: I,
     working_dir: Option<P>,
     verbosity: Verbosity,
     env: Vec<(&str, Option<String>)>,
-) -> Result<Vec<u8>>
+) -> Expression
 where
     I: IntoIterator<Item = S> + std::fmt::Debug,
-    S: AsRef<OsStr>,
+    S: Into<OsString>,
     P: AsRef<Path>,
 {
     let cargo = std::env::var("CARGO").unwrap_or_else(|_| "cargo".to_string());
-    let mut cmd = Command::new(cargo);
+    let mut cmd_args = Vec::new();
+
+    cmd_args.push(command);
+    cmd_args.push("--color=always");
+
+    match verbosity {
+        Verbosity::Quiet => cmd_args.push("--quiet"),
+        Verbosity::Verbose => {
+            if command != "dylint" {
+                cmd_args.push("--verbose")
+            }
+        }
+        Verbosity::Default => (),
+    };
+
+    let mut cmd_args: Vec<OsString> = cmd_args.iter().map(Into::into).collect();
+    for arg in args {
+        cmd_args.push(arg.into());
+    }
+
+    let mut cmd = duct::cmd(cargo, &cmd_args);
 
     env.iter().for_each(|(env_key, maybe_env_val)| {
         match maybe_env_val {
-            Some(env_val) => cmd.env(env_key, env_val),
-            None => cmd.env_remove(env_key),
+            Some(env_val) => cmd = cmd.env(env_key, env_val),
+            None => cmd = cmd.env_remove(env_key),
         };
     });
 
     if let Some(path) = working_dir {
         tracing::debug!("Setting cargo working dir to '{}'", path.as_ref().display());
-        cmd.current_dir(path);
+        cmd = cmd.dir(path.as_ref());
     }
 
-    cmd.arg(command);
-    cmd.args(args);
-    match verbosity {
-        Verbosity::Quiet => cmd.arg("--quiet"),
-        Verbosity::Verbose => {
-            if command != "dylint" {
-                cmd.arg("--verbose")
-            } else {
-                &mut cmd
-            }
-        }
-        Verbosity::Default => &mut cmd,
-    };
+    cmd
+}
 
-    tracing::debug!("Invoking cargo: {:?}", cmd);
-
-    let child = cmd
-        // capture the stdout to return from this function as bytes
-        .stdout(std::process::Stdio::piped())
-        .spawn()
-        .context(format!("Error executing `{cmd:?}`"))?;
-    let output = child.wait_with_output()?;
-
-    if output.status.success() {
-        Ok(output.stdout)
-    } else {
-        anyhow::bail!(
-            "`{:?}` failed with exit code: {:?}",
-            cmd,
-            output.status.code()
-        );
-    }
+/// Configures the cargo command to output colour and the progress bar.
+pub fn cargo_tty_output(cmd: Expression) -> Expression {
+    #[cfg(windows)]
+    let term_size = "100";
+
+    #[cfg(not(windows))]
+    let term_size = term_size::dimensions_stderr()
+        .map(|(width, _)| width.to_string())
+        .unwrap_or_else(|| "100".to_string());
+
+    cmd.env("CARGO_TERM_COLOR", "always")
+        .env("CARGO_TERM_PROGRESS_WIDTH", term_size)
+        .env("CARGO_TERM_PROGRESS_WHEN", "always")
 }
 
 /// Returns the base name of the path.