Fix tests not using appropriate target data

crates/project-model/src/target_data_layout.rs

@@ -0,0 +1,40 @@
+//! Runs `rustc --print target-spec-json` to get the target_data_layout.
+use std::process::Command;
+
+use rustc_hash::FxHashMap;
+
+use crate::{utf8_stdout, ManifestPath};
+
+pub(super) fn get(
+    cargo_toml: Option<&ManifestPath>,
+    target: Option<&str>,
+    extra_env: &FxHashMap<String, String>,
+) -> Option<String> {
+    let output = (|| {
+        if let Some(cargo_toml) = cargo_toml {
+            let mut cmd = Command::new(toolchain::rustc());
+            cmd.envs(extra_env);
+            cmd.current_dir(cargo_toml.parent())
+                .args(&["-Z", "unstable-options", "rustc", "--print", "target-spec-json"])
+                .env("RUSTC_BOOTSTRAP", "1");
+            if let Some(target) = target {
+                cmd.args(&["--target", target]);
+            }
+            match utf8_stdout(cmd) {
+                Ok(it) => return Ok(it),
+                Err(e) => tracing::debug!("{e:?}: falling back to querying rustc for cfgs"),
+            }
+        }
+        // using unstable cargo features failed, fall back to using plain rustc
+        let mut cmd = Command::new(toolchain::rustc());
+        cmd.envs(extra_env)
+            .args(&["-Z", "unstable-options", "rustc", "--print", "target-spec-json"])
+            .env("RUSTC_BOOTSTRAP", "1");
+        if let Some(target) = target {
+            cmd.args(&["--target", target]);
+        }
+        utf8_stdout(cmd)
+    })()
+    .ok()?;
+    Some(output.split_once(r#""data-layout": ""#)?.1.split_once('"')?.0.to_owned())
+}