try using record dots with TH

cabal.project

@@ -5,10 +5,10 @@ packages: .
 -- so we specify the equivalent commit SHAs manually instead
 source-repository-package
   type: git
-  location: https://github.com/well-typed/hs-bindgen
-  tag: e2a9260678d9fa76dab602a5a07927acada3be4f
+  location: https://github.com/georgefst/hs-bindgen
+  tag: 3693360bcd1f8478932c4944c70baca7c4ecf950
   subdir: c-expr-dsl c-expr-runtime hs-bindgen hs-bindgen-runtime
-  --sha256: 0nrs3iq0l5ha5kxyhqnlmvgi7734pmzyp3zf7p8s1gb21ylh4sy0
+  --sha256: lV2FwS80iHhJU6iie/F24W4dYV+vvmeTu6465NLnOb4=
 source-repository-package
   type: git
   location: https://github.com/well-typed/libclang

generate-bindings

@@ -19,7 +19,7 @@ set -euo pipefail
 SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
 RUST_DIR="$SCRIPT_DIR/rust"
 HEADER_NAME="garnet_rs.h"
-HEADER="$RUST_DIR/target/debug/$HEADER_NAME"
+HEADER="$RUST_DIR/$HEADER_NAME"
 
 # --- Step 1: Build Rust static library ---
 echo "=== Building Rust library ==="
@@ -66,7 +66,7 @@ echo "  Patched header at $HEADER"
 echo "=== Configuring Cabal ==="
 cabal configure \
   --extra-lib-dirs="$RUST_DIR/target/debug" \
-  --extra-include-dirs="$RUST_DIR/target/debug"
+  --extra-include-dirs="$RUST_DIR"
 
 echo "=== Done ==="
 echo "Run 'cabal run' to test."

lib/GarnetRs/Raw.hs

@@ -1,6 +1,7 @@
 {-# LANGUAGE CApiFFI #-}
 {-# LANGUAGE DerivingVia #-}
 {-# LANGUAGE FieldSelectors #-}
+-- {-# LANGUAGE NoFieldSelectors #-}
 {-# LANGUAGE MagicHash #-}
 {-# LANGUAGE PatternSynonyms #-}
 {-# LANGUAGE TemplateHaskell #-}
@@ -40,7 +41,10 @@ do
             <$> runIO (readProcessWithExitCode "cpp" ["-v"] "")
     withHsBindgen
         def
-            { clang = def{extraIncludeDirs = Pkg "rust/target/debug" : systemDirs}
+            { clang = def{extraIncludeDirs = Pkg "rust" : systemDirs}
+            -- hmm, I guess there's a reason this wasn't exported
+            -- , fieldNamingStrategy = EnableRecordDot
+            , fieldNamingStrategy = PrefixedFieldNames
             }
         def
         $ hashInclude "garnet_rs.h"

rust/garnet_rs.h

@@ -0,0 +1,63 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+struct T {
+  bool a;
+  uint8_t b;
+};
+
+enum Shape_Tag {
+  Circle,
+  Rectangle,
+};
+
+struct Circle_Body {
+  double radius;
+};
+
+struct Rectangle_Body {
+  double width;
+  double height;
+};
+
+struct Shape {
+  enum Shape_Tag tag;
+  union {
+    struct Circle_Body circle;
+    struct Rectangle_Body rectangle;
+  } body;
+};
+
+enum BTreeC_Tag {
+  Leaf,
+  Fork,
+};
+
+struct Leaf_Body {
+  int64_t value;
+};
+
+struct Fork_Body {
+  const struct BTreeC *left;
+  const struct BTreeC *right;
+};
+
+struct BTreeC {
+  enum BTreeC_Tag tag;
+  union {
+    struct Leaf_Body leaf;
+    struct Fork_Body fork;
+  } body;
+};
+
+void hello(const char *c);
+
+void hello_struct(struct T t);
+
+void hello_shape(struct Shape s);
+
+__attribute__((const)) int64_t add(int64_t a, int64_t b);
+
+int64_t sum_tree(struct BTreeC t);