feat(solc): support rustup-like version specifiers (+x.y.z) (#125)

crates/svm-rs/src/bin/solc/main.rs

@@ -1,4 +1,4 @@
-//! Simple Solc wrapper that delegates everything to the global [`svm`] version.
+//! Simple Solc wrapper that delegates everything to a specified or the global [`svm`] Solc version.
 
 #![doc(
     html_logo_url = "https://raw.githubusercontent.com/alloy-rs/core/main/assets/alloy.jpg",
@@ -8,17 +8,57 @@
 #![deny(unused_must_use, rust_2018_idioms)]
 #![cfg_attr(docsrs, feature(doc_cfg, doc_auto_cfg))]
 
+use anyhow::Context;
 use std::process::{Command, Stdio};
 
-fn main() -> anyhow::Result<()> {
-    let version = svm::get_global_version()?.ok_or(svm::SvmError::GlobalVersionNotSet)?;
-    let program = svm::version_binary(&version.to_string());
-    let status = Command::new(program)
-        .args(std::env::args_os().skip(1))
+fn main() {
+    let code = match main_() {
+        Ok(code) => code,
+        Err(err) => {
+            eprintln!("svm: error: {err:?}");
+            1
+        }
+    };
+    std::process::exit(code);
+}
+
+fn main_() -> anyhow::Result<i32> {
+    let mut args = std::env::args_os().skip(1).peekable();
+    let version = 'v: {
+        // Try to parse the first argument as a version specifier `+x.y.z`.
+        if let Some(arg) = args.peek() {
+            if let Some(arg) = arg.to_str() {
+                if let Some(stripped) = arg.strip_prefix('+') {
+                    let version = stripped
+                        .parse::<semver::Version>()
+                        .context("failed to parse version specifier")?;
+                    if !version.build.is_empty() || !version.pre.is_empty() {
+                        anyhow::bail!(
+                            "version specifier must not have pre-release or build metadata"
+                        );
+                    }
+                    args.next();
+                    break 'v version;
+                }
+            }
+        }
+        // Fallback to the global version if one is not specified.
+        svm::get_global_version()?.ok_or(svm::SvmError::GlobalVersionNotSet)?
+    };
+
+    let bin = svm::version_binary(&version.to_string());
+    if !bin.exists() {
+        anyhow::bail!(
+            "Solc version {version} is not installed or does not exist; looked at {}",
+            bin.display()
+        );
+    }
+
+    let status = Command::new(bin)
+        .args(args)
         .stdin(Stdio::inherit())
         .stdout(Stdio::inherit())
         .stderr(Stdio::inherit())
         .status()?;
-    let code = status.code().unwrap_or(-1);
-    std::process::exit(code);
+    Ok(status.code().unwrap_or(-1))
 }