wasi example: theres lots of useful tracing messages for debugging

Cargo.lock

@@ -2419,6 +2419,8 @@ dependencies = [
  "target-lexicon",
  "tempfile",
  "test-programs",
+ "tracing",
+ "tracing-subscriber",
  "wasi-common",
  "wasmtime",
  "wasmtime-cache",

Cargo.toml

@@ -51,6 +51,8 @@ tempfile = "3.1.0"
 test-programs = { path = "crates/test-programs" }
 wasmtime-fuzzing = { path = "crates/fuzzing" }
 wasmtime-runtime = { path = "crates/runtime" }
+tracing = "0.1.12"
+tracing-subscriber = "0.2.0"
 
 [build-dependencies]
 anyhow = "1.0.19"

examples/wasi/main.rs

@@ -8,6 +8,11 @@ use wasmtime::*;
 use wasmtime_wasi::{Wasi, WasiCtx};
 
 fn main() -> Result<()> {
+    tracing_subscriber::FmtSubscriber::builder()
+        .with_env_filter(tracing_subscriber::EnvFilter::from_default_env())
+        .with_ansi(true)
+        .init();
+
     let store = Store::default();
     let mut linker = Linker::new(&store);