1 files changed, 41 insertions, 0 deletions
diff --git a/vendor/rustc_apfloat/build.rs b/vendor/rustc_apfloat/build.rs
new file mode 100644
index 000000000..a7398a28a
--- /dev/null
+++ b/vendor/rustc_apfloat/build.rs
@@ -0,0 +1,41 @@
+// HACK(eddyb) easier dep-tracking if we let `rustc` do it.
+const SRC_LIB_RS_CONTENTS: &str = include_str!("src/lib.rs");
+
+const EXPECTED_SRC_LIB_RS_PREFIX: &str = "\
+//! Port of LLVM's APFloat software floating-point implementation from the
+//! following C++ sources (please update commit hash when backporting):
+//! https://github.com/llvm/llvm-project/commit/";
+
+fn main() {
+    // HACK(eddyb) disable the default of re-running the build script on *any*
+    // change to *the entire source tree* (i.e. the default is roughly `./`).
+    println!("cargo:rerun-if-changed=build.rs");
+
+    let llvm_commit_hash = SRC_LIB_RS_CONTENTS
+        .strip_prefix(EXPECTED_SRC_LIB_RS_PREFIX)
+        .ok_or(())
+        .map_err(|_| format!("expected `src/lib.rs` to start with:\n\n{EXPECTED_SRC_LIB_RS_PREFIX}"))
+        .and_then(|commit_hash_plus_rest_of_file| {
+            Ok(commit_hash_plus_rest_of_file
+                .split_once('\n')
+                .ok_or("expected `src/lib.rs` to have more than 3 lines")?)
+        })
+        .and_then(|(commit_hash, _)| {
+            if commit_hash.len() != 40 || !commit_hash.chars().all(|c| matches!(c, '0'..='9'|'a'..='f')) {
+                Err(format!("expected `src/lib.rs` to have a valid commit hash, found {commit_hash:?}"))
+            } else {
+                Ok(commit_hash)
+            }
+        })
+        .unwrap_or_else(|e| {
+            eprintln!("\n{e}\n");
+            panic!("failed to validate `src/lib.rs`'s commit hash (see above)")
+        });
+
+    let expected_version_metadata = format!("+llvm-{}", &llvm_commit_hash[..12]);
+    let actual_version = env!("CARGO_PKG_VERSION");
+    if !actual_version.ends_with(&expected_version_metadata) {
+        eprintln!("\nexpected version ending in `{expected_version_metadata}`, found `{actual_version}`\n");
+        panic!("failed to validate Cargo package version (see above)");
+    }
+}