Auto merge of #2402 - RalfJung:cargo-target, r=RalfJung

cargo-miri: reorder --target to after the user-defined commands

This should help with #2398.

Author: bors

cargo-miri/bin.rs

@@ -609,27 +609,12 @@ fn phase_cargo_miri(mut args: env::Args) {
         MiriCommand::Forward(s) => s,
         MiriCommand::Setup => return, // `cargo miri setup` stops here.
     };
+    let metadata = get_cargo_metadata();
     let mut cmd = cargo();
     cmd.arg(cargo_cmd);
 
-    // Make sure we know the build target, and cargo does, too.
-    // This is needed to make the `CARGO_TARGET_*_RUNNER` env var do something,
-    // and it later helps us detect which crates are proc-macro/build-script
-    // (host crates) and which crates are needed for the program itself.
-    let host = version_info().host;
-    let target = get_arg_flag_value("--target");
-    let target = if let Some(ref target) = target {
-        target
-    } else {
-        // No target given. Pick default and tell cargo about it.
-        cmd.arg("--target");
-        cmd.arg(&host);
-        &host
-    };
-
-    let mut target_dir = None;
-
     // Forward all arguments before `--` other than `--target-dir` and its value to Cargo.
+    let mut target_dir = None;
     for arg in ArgSplitFlagValue::new(&mut args, "--target-dir") {
         match arg {
             Ok(value) => {
@@ -643,16 +628,27 @@ fn phase_cargo_miri(mut args: env::Args) {
             }
         }
     }
-
-    let metadata = get_cargo_metadata();
-
     // Detect the target directory if it's not specified via `--target-dir`.
     let target_dir = target_dir.get_or_insert_with(|| metadata.target_directory.clone());
-
     // Set `--target-dir` to `miri` inside the original target directory.
     target_dir.push("miri");
     cmd.arg("--target-dir").arg(target_dir);
 
+    // Make sure we know the build target, and cargo does, too.
+    // This is needed to make the `CARGO_TARGET_*_RUNNER` env var do something,
+    // and it later helps us detect which crates are proc-macro/build-script
+    // (host crates) and which crates are needed for the program itself.
+    let host = version_info().host;
+    let target = get_arg_flag_value("--target");
+    let target = if let Some(ref target) = target {
+        target
+    } else {
+        // No target given. Pick default and tell cargo about it.
+        cmd.arg("--target");
+        cmd.arg(&host);
+        &host
+    };
+
     // Forward all further arguments after `--` to cargo.
     cmd.arg("--").args(args);