Merge pull request #20804 from itsjunetime/run_correct_pgo_r-a

Build rust-analyzer with `--target` for install/pgo xtask

xtask/src/install.rs

diff --git a/xtask/src/install.rs b/xtask/src/install.rs
index f0cc445..b794f53 100644
--- a/xtask/src/install.rs
+++ b/xtask/src/install.rs
@@ -145,12 +145,12 @@
     );
 
     if let Some(train_crate) = opts.pgo {
+        let target = detect_target(sh);
         let build_cmd = cmd!(
             sh,
-            "cargo build --manifest-path ./crates/rust-analyzer/Cargo.toml --bin rust-analyzer --profile={profile} --locked --features force-always-assert {features...}"
+            "cargo build --manifest-path ./crates/rust-analyzer/Cargo.toml --bin rust-analyzer --target {target} --profile={profile} --locked --features force-always-assert {features...}"
         );
 
-        let target = detect_target(sh);
         let profile = crate::pgo::gather_pgo_profile(sh, build_cmd, &target, train_crate)?;
         install_cmd = crate::pgo::apply_pgo_to_cmd(install_cmd, &profile);
     }

xtask/src/pgo.rs

diff --git a/xtask/src/pgo.rs b/xtask/src/pgo.rs
index 7f7b331..0c6f499 100644
--- a/xtask/src/pgo.rs
+++ b/xtask/src/pgo.rs
@@ -53,14 +53,23 @@
 
     // Merge profiles into a single file
     let merged_profile = pgo_dir.join("merged.profdata");
-    let profile_files = std::fs::read_dir(pgo_dir)?.filter_map(|entry| {
-        let entry = entry.ok()?;
-        if entry.path().extension() == Some(OsStr::new("profraw")) {
-            Some(entry.path().to_str().unwrap().to_owned())
-        } else {
-            None
-        }
-    });
+    let profile_files = std::fs::read_dir(pgo_dir)?
+        .filter_map(|entry| {
+            let entry = entry.ok()?;
+            if entry.path().extension() == Some(OsStr::new("profraw")) {
+                Some(entry.path().to_str().unwrap().to_owned())
+            } else {
+                None
+            }
+        })
+        .collect::<Vec<_>>();
+
+    if profile_files.is_empty() {
+        anyhow::bail!(
+            "rust-analyzer analysis-stats produced no pgo files. This is a bug in rust-analyzer; please file an issue."
+        );
+    }
+
     cmd!(sh, "{llvm_profdata} merge {profile_files...} -o {merged_profile}").run().context(
         "cannot merge PGO profiles. Do you have the rustup `llvm-tools` component installed?",
     )?;