Remove regex dependency from build to improve compile time

Cargo.toml

@@ -40,7 +40,6 @@ serde_json = "1.0.68"
 tempfile = "3.2.0"
 url = { version = "2.2.2", features = ["serde"] }
 impl-serde = "0.3.1"
-regex = "1.4"
 
 # dependencies for optional extrinsics feature
 async-std = { version = "1.10.0", optional = true }
@@ -62,6 +61,7 @@ platforms = "1.1"
 [dev-dependencies]
 assert_matches = "1.5.0"
 pretty_assertions = "0.7.2"
+regex = "1.4"
 wabt = "0.10.0"
 
 [features]

src/cmd/build.rs

@@ -24,7 +24,6 @@ use crate::{
 use anyhow::{Context, Result};
 use colored::Colorize;
 use parity_wasm::elements::{External, Internal, MemoryType, Module, Section};
-use regex::Regex;
 use semver::Version;
 use std::{
     convert::TryFrom,
@@ -531,24 +530,17 @@ fn check_wasm_opt_version_compatibility(wasm_opt_path: &Path) -> Result<()> {
     let version_stdout = str::from_utf8(&cmd.stdout)
         .expect("Cannot convert stdout output of wasm-opt to string")
         .trim();
-    let re = Regex::new(r"wasm-opt version (\d+)").expect("invalid regex");
-    let captures = re.captures(version_stdout).ok_or_else(|| {
-        anyhow::anyhow!(
+    let parts = version_stdout.split(" ").collect::<Vec<_>>();
+
+    if parts.len() < 3 || parts[0] != "wasm-opt" || parts[1] != "version" {
+        return Err(anyhow::anyhow!(
             "Unable to extract version information from '{}'.\n\
             Your wasm-opt version is most probably too old. Make sure you use a version >= 99.{}",
             version_stdout,
             github_note,
-        )
-    })?;
-    let version_number: u32 = captures
-        .get(1) // first capture group is at index 1
-        .ok_or_else(|| {
-            anyhow::anyhow!(
-                "Unable to extract version number from '{:?}'",
-                version_stdout
-            )
-        })?
-        .as_str()
+        ))
+    };
+    let version_number: u32 = parts[2]
         .parse()
         .map_err(|err| {
             anyhow::anyhow!(