cargo sqlx prepare: fix to consistently trigger recompile

sqlx-cli/src/lib.rs

@@ -37,7 +37,8 @@ pub enum Command {
         #[structopt(long)]
         check: bool,
 
-        /// Any arguments to pass to `cargo check`.
+        /// Any arguments to pass to `cargo rustc`;
+        /// Cargo args (preceding `--` in `cargo rustc ... -- ...`) only.
         #[structopt(name = "Cargo args", last = true)]
         cargo_args: Vec<String>,
     },

sqlx-cli/src/prepare.rs

@@ -76,13 +76,17 @@ fn run_prepare_step(cargo_args: Vec<String>) -> anyhow::Result<QueryData> {
         .context("`prepare` subcommand may only be invoked as `cargo sqlx prepare``")?;
 
     let check_status = Command::new(&cargo)
-        .arg("check")
+        .arg("rustc")
         .args(cargo_args)
-        // set an always-changing env var that the macros depend on via `env!()`
-        .env(
-            "__SQLX_RECOMPILE_TRIGGER",
-            SystemTime::UNIX_EPOCH.elapsed()?.as_millis().to_string(),
-        )
+        .arg("--")
+        .arg("--emit")
+        .arg("dep-info,metadata")
+        // set an always-changing cfg so we can consistently trigger recompile
+        .arg("--cfg")
+        .arg(format!(
+            "__sqlx_recompile_trigger=\"{}\"",
+            SystemTime::UNIX_EPOCH.elapsed()?.as_millis()
+        ))
         .status()?;
 
     if !check_status.success() {

sqlx-macros/src/query/mod.rs

@@ -222,9 +222,6 @@ where
             (#($#arg_names:expr),*) => {{
                 use sqlx::arguments::Arguments as _;
 
-                // lets `cargo sqlx prepare` ensure that we can always trigger a recompile
-                const _: Option<&'static str> = option_env!("__SQLX_RECOMPILE_TRIGGER");
-
                 #args_tokens
 
                 #output