From 3154bf89a712e1ea20255b5f56d8fb7d3b7d2ca1 Mon Sep 17 00:00:00 2001
From: Daniel Eades <danieleades@hotmail.com>
Date: Sun, 12 Jul 2026 07:12:48 +0100
Subject: [PATCH] Report malformed schema JSON as a compile error instead of
 panicking

Previously, import_types! unwrapped the serde_json parse result, so a
syntax error in the schema file surfaced as an opaque "proc macro
panicked" error. Map the parse error to a spanned syn::Error, matching
the existing handling of file-open failures and preserving serde_json's
line/column information.
---
 typify-macro/src/lib.rs                       | 21 ++++++++++++-------
 typify/tests/compile-fail/malformed-schema.rs |  6 ++++++
 .../compile-fail/malformed-schema.stderr      |  5 +++++
 typify/tests/compile_fail.rs                  |  6 ++++++
 4 files changed, 30 insertions(+), 8 deletions(-)
 create mode 100644 typify/tests/compile-fail/malformed-schema.rs
 create mode 100644 typify/tests/compile-fail/malformed-schema.stderr
 create mode 100644 typify/tests/compile_fail.rs

diff --git a/typify-macro/src/lib.rs b/typify-macro/src/lib.rs
index 69b74026..fd3a2dbf 100644
--- a/typify-macro/src/lib.rs
+++ b/typify-macro/src/lib.rs
@@ -252,14 +252,19 @@ fn do_import_types(item: TokenStream) -> Result<TokenStream, syn::Error> {
 
     let path = dir.join(schema.value());
 
-    let root_schema: schemars::schema::RootSchema =
-        serde_json::from_reader(std::fs::File::open(&path).map_err(|e| {
-            syn::Error::new(
-                schema.span(),
-                format!("couldn't read file {}: {}", schema.value(), e),
-            )
-        })?)
-        .unwrap();
+    let file = std::fs::File::open(&path).map_err(|e| {
+        syn::Error::new(
+            schema.span(),
+            format!("couldn't read file {}: {}", schema.value(), e),
+        )
+    })?;
+
+    let root_schema: schemars::schema::RootSchema = serde_json::from_reader(file).map_err(|e| {
+        syn::Error::new(
+            schema.span(),
+            format!("couldn't parse file {}: {}", schema.value(), e),
+        )
+    })?;
 
     let mut type_space = TypeSpace::new(&settings);
     type_space
diff --git a/typify/tests/compile-fail/malformed-schema.rs b/typify/tests/compile-fail/malformed-schema.rs
new file mode 100644
index 00000000..b7a31fdb
--- /dev/null
+++ b/typify/tests/compile-fail/malformed-schema.rs
@@ -0,0 +1,6 @@
+use typify::import_types;
+
+// Cargo.toml exists in trybuild's generated crate but is not valid JSON.
+import_types!("Cargo.toml");
+
+fn main() {}
diff --git a/typify/tests/compile-fail/malformed-schema.stderr b/typify/tests/compile-fail/malformed-schema.stderr
new file mode 100644
index 00000000..14eaee79
--- /dev/null
+++ b/typify/tests/compile-fail/malformed-schema.stderr
@@ -0,0 +1,5 @@
+error: couldn't parse file Cargo.toml: invalid type: sequence, expected struct RootSchema at line 1 column 1
+ --> tests/compile-fail/malformed-schema.rs:4:15
+  |
+4 | import_types!("Cargo.toml");
+  |               ^^^^^^^^^^^^
diff --git a/typify/tests/compile_fail.rs b/typify/tests/compile_fail.rs
new file mode 100644
index 00000000..1c61f8af
--- /dev/null
+++ b/typify/tests/compile_fail.rs
@@ -0,0 +1,6 @@
+// Copyright 2026 Oxide Computer Company
+
+#[test]
+fn test_compile_fail() {
+    trybuild::TestCases::new().compile_fail("tests/compile-fail/*.rs");
+}