fix: use manual FFI declarations for pm_line_column_t and pm_newline_list_line_column

Bindgen cannot generate bindings for these symbols on the WASM target,
causing CI failures. Replace the bindgen allowlist entries with hand-
written repr(C) struct and extern C declarations so they work on all
targets (native and WASM).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: sei40kr

rust/ruby-prism-sys/build/main.rs

@@ -116,7 +116,6 @@ fn generate_bindings(ruby_include_path: &Path) -> bindgen::Bindings {
         // Structs
         .allowlist_type("pm_comment_t")
         .allowlist_type("pm_diagnostic_t")
-        .allowlist_type("pm_line_column_t")
         .allowlist_type("pm_list_t")
         .allowlist_type("pm_magic_comment_t")
         .allowlist_type("pm_node_t")
@@ -141,8 +140,6 @@ fn generate_bindings(ruby_include_path: &Path) -> bindgen::Bindings {
         // Functions
         .allowlist_function("pm_list_empty_p")
         .allowlist_function("pm_list_free")
-        .allowlist_function("pm_newline_list_line")
-        .allowlist_function("pm_newline_list_line_column")
         .allowlist_function("pm_node_destroy")
         .allowlist_function("pm_pack_parse")
         .allowlist_function("pm_parse")

rust/ruby-prism-sys/src/lib.rs

@@ -35,3 +35,25 @@ mod bindings {
 }
 
 pub use self::bindings::*;
+
+/// Line and column information for a given byte offset relative to the
+/// beginning of the source.
+#[repr(C)]
+#[derive(Debug, Clone, Copy)]
+pub struct pm_line_column_t {
+    /// The 1-indexed line number relative to the start line configured on the
+    /// parser.
+    pub line: i32,
+    /// The 0-indexed column number in bytes.
+    pub column: u32,
+}
+
+extern "C" {
+    /// Return the line and column number for the given byte offset relative to
+    /// the beginning of the source.
+    pub fn pm_newline_list_line_column(
+        list: *const pm_newline_list_t,
+        cursor: u32,
+        start_line: i32,
+    ) -> pm_line_column_t;
+}

rust/ruby-prism/src/parse_result/mod.rs

@@ -104,22 +104,19 @@ impl<'pr> Location<'pr> {
         }
     }
 
-    fn line_column_at(&self, offset: u32) -> LineColumn {
+    fn line_column_at(&self, offset: u32) -> ruby_prism_sys::pm_line_column_t {
+        // SAFETY: `self.parser` is a valid pointer to a `pm_parser_t` that
+        // outlives `self`, and `pm_newline_list_line_column` only reads from
+        // the newline list.
         unsafe {
             let parser = self.parser.as_ptr();
             let newline_list = &(*parser).newline_list;
             let start_line = (*parser).start_line;
-            let result = pm_newline_list_line_column(newline_list, offset, start_line);
-            LineColumn { line: result.line, column: result.column }
+            pm_newline_list_line_column(newline_list, offset, start_line)
         }
     }
 }
 
-struct LineColumn {
-    line: i32,
-    column: u32,
-}
-
 impl std::fmt::Debug for Location<'_> {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         let slice: &[u8] = self.as_slice();