rustc_public: Add tests for some Serialize impls

Author: aDotInTheVoid

Cargo.lock

@@ -4440,6 +4440,7 @@ dependencies = [
  "rustc_target",
  "scoped-tls",
  "serde",
+ "serde_json",
  "tracing",
 ]
 

compiler/rustc_public/Cargo.toml

@@ -13,10 +13,15 @@ rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
 rustc_target = { path = "../rustc_target" }
 scoped-tls = "1.0"
-serde = { version = "1.0.125", features = [ "derive" ] }
+serde = { version = "1.0.125", features = ["derive"] }
 tracing = "0.1"
 # tidy-alphabetical-end
 
+[dev-dependencies]
+# tidy-alphabetical-start
+serde_json = "1.0.142"
+# tidy-alphabetical-end
+
 [features]
 # tidy-alphabetical-start
 # Provides access to APIs that expose internals of the rust compiler.

compiler/rustc_public/src/lib.rs

@@ -53,6 +53,8 @@ pub mod compiler_interface;
 pub mod error;
 pub mod mir;
 pub mod target;
+#[cfg(test)]
+mod tests;
 pub mod ty;
 pub mod visitor;
 

compiler/rustc_public/src/tests.rs

@@ -0,0 +1,63 @@
+use rustc_public_bridge::IndexedVal;
+
+use crate::abi::Layout;
+use crate::mir::alloc::AllocId;
+use crate::mir::mono::InstanceDef;
+use crate::ty::{MirConstId, TyConstId, VariantIdx};
+use crate::{CrateNum, DefId, Span, ThreadLocalIndex, Ty};
+
+#[track_caller]
+fn check_serialize<T: serde::Serialize>(value: T, expected_json: &str) {
+    let got_json = serde_json::to_string(&value).unwrap();
+    assert_eq!(got_json, expected_json, "didn't get expected json for serializing");
+}
+
+#[test]
+fn serialize_cratenum() {
+    check_serialize(CrateNum(1, ThreadLocalIndex), "1");
+}
+
+#[test]
+fn serialize_defid() {
+    check_serialize(DefId::to_val(2), "2");
+}
+
+#[test]
+fn serialize_layout() {
+    check_serialize(Layout::to_val(3), "3");
+}
+
+#[test]
+fn serialize_allocid() {
+    check_serialize(AllocId::to_val(4), "4");
+}
+
+#[test]
+fn serialize_ty() {
+    check_serialize(Ty::to_val(5), "5");
+}
+
+#[test]
+fn serialize_tyconstid() {
+    check_serialize(TyConstId::to_val(6), "6");
+}
+
+#[test]
+fn serialize_mirconstid() {
+    check_serialize(MirConstId::to_val(7), "7");
+}
+
+#[test]
+fn serialize_span() {
+    check_serialize(Span::to_val(8), "8");
+}
+
+#[test]
+fn serialize_variantidx() {
+    check_serialize(VariantIdx::to_val(9), "9");
+}
+
+#[test]
+fn serialize_instancedef() {
+    check_serialize(InstanceDef::to_val(10), "10");
+}