Minor logging tweaks

Some things I noticed from bytecodealliance#7239 which are very much not critical but I
figure might be nice-to-haves:

* Move the logging configuration to the `wasmtime-cli-flags` crate with
  the other logging configuration to keep it in one place.
* Remove `pretty_env_logger` since `tracing-subscriber` probably
  supplants it.
* Don't explicitly inherit env vars in tests since that happens
  automatically with `Command`.

Cargo.toml

@@ -39,7 +39,6 @@ wasmtime-runtime = { workspace = true }
 clap = { workspace = true, features = ["color", "suggestions", "derive"] }
 anyhow = { workspace = true }
 target-lexicon = { workspace = true }
-tracing-subscriber = { workspace = true }
 once_cell = { workspace = true }
 listenfd = "1.0.0"
 wat = { workspace = true }

crates/cli-flags/Cargo.toml

@@ -12,7 +12,7 @@ edition.workspace = true
 anyhow = { workspace = true }
 clap = { workspace = true }
 file-per-thread-logger = { workspace = true }
-pretty_env_logger = { workspace = true }
+tracing-subscriber = { workspace = true }
 rayon = "1.5.0"
 wasmtime = { workspace = true }
 humantime = "2.0.0"

crates/cli-flags/src/lib.rs

@@ -5,7 +5,9 @@
 
 use anyhow::Result;
 use clap::Parser;
+use std::io::IsTerminal;
 use std::time::Duration;
+use tracing_subscriber::{EnvFilter, FmtSubscriber};
 use wasmtime::Config;
 
 pub mod opt;
@@ -328,7 +330,13 @@ impl CommonOptions {
             let prefix = "wasmtime.dbg.";
             init_file_per_thread_logger(prefix);
         } else {
-            pretty_env_logger::init();
+            let mut b = FmtSubscriber::builder()
+                .with_writer(std::io::stderr)
+                .with_env_filter(EnvFilter::from_env("WASMTIME_LOG"));
+            if std::io::stderr().is_terminal() {
+                b = b.with_ansi(true);
+            }
+            b.init();
         }
     }
 

src/bin/wasmtime.rs

@@ -82,16 +82,6 @@ impl Wasmtime {
 }
 
 fn main() -> Result<()> {
-    use std::io::IsTerminal;
-    use tracing_subscriber::{EnvFilter, FmtSubscriber};
-
-    let mut b = FmtSubscriber::builder()
-        .with_writer(std::io::stderr)
-        .with_env_filter(EnvFilter::from_env("WASMTIME_LOG"));
-    if std::io::stderr().is_terminal() {
-        b = b.with_ansi(true);
-    }
-    b.init();
     Wasmtime::parse().execute()
 }
 

tests/all/cli_tests.rs

@@ -32,7 +32,7 @@ pub fn get_wasmtime_command() -> Result<Command> {
     // If we're running tests with a "runner" then we might be doing something
     // like cross-emulation, so spin up the emulator rather than the tests
     // itself, which may not be natively executable.
-    let mut cmd = if let Some((_, runner)) = runner {
+    let cmd = if let Some((_, runner)) = runner {
         let mut parts = runner.split_whitespace();
         let mut cmd = Command::new(parts.next().unwrap());
         for arg in parts {
@@ -44,10 +44,6 @@ pub fn get_wasmtime_command() -> Result<Command> {
         Command::new(&me)
     };
 
-    if let Ok(val) = std::env::var("WASMTIME_LOG") {
-        cmd.env("WASMTIME_LOG", val);
-    }
-
     Ok(cmd)
 }