WIP: Basic libclang bindings

This adds all bindings required to translate the `libclang` tutorial to
Haskell.

.gitignore

@@ -2,3 +2,4 @@
 dist-newstyle/
 unversioned
 cabal.project.local
+.vscode/

hs-bindgen/cbits/clang_wrappers.c

@@ -0,0 +1,25 @@
+#include <stdlib.h>
+#include <string.h>
+
+#include <clang-c/Index.h>
+
+#include "clang_wrappers.h"
+
+/**
+ * Cursor manipulations
+ */
+
+CXCursor* wrap_malloc_getTranslationUnitCursor (CXTranslationUnit unit) {
+    CXCursor result = clang_getTranslationUnitCursor(unit);
+    CXCursor *wrapped = malloc(sizeof(CXCursor));
+    memcpy(wrapped, &result, sizeof(CXCursor));
+    return wrapped;
+}
+
+/**
+ * Traversing the AST with cursors
+ */
+
+unsigned wrap_visitChildren(CXCursor* parent, CXCursorVisitor visitor, CXClientData client_data) {
+    return clang_visitChildren(*parent, visitor, client_data);
+}

hs-bindgen/cbits/clang_wrappers.h

@@ -0,0 +1,19 @@
+/**
+ * Wrappers for clang functions that take structs, or return them, by value.
+ *
+ * For functions that return structs by value, we instead allocate memory and
+ * return a pointer. It is the responsibility of the caller to attach a
+ * finalizer to these pointers; to remind the caller to do so, these functions
+ * are prefixed with @wrap_malloc_@; the other functions are prefixed with
+ * @wrap_@ (in both cases this prefixes replaces the @clang_@ prefix).
+ */
+
+#include <clang-c/Index.h>
+
+// Cursor manipulations
+
+CXCursor* wrap_malloc_getTranslationUnitCursor (CXTranslationUnit unit);
+
+// Traversing the AST with cursors
+
+unsigned wrap_visitChildren(CXCursor* parent, CXCursorVisitor visitor, CXClientData);

hs-bindgen/hs-bindgen.cabal

@@ -9,6 +9,8 @@ category:           Development
 build-type:         Simple
 synopsis:           Generate Haskell bindings from C headers
 extra-doc-files:    CHANGELOG.md
+extra-source-files: cbits/*.c
+                    cbits/*.h
 tested-with:      , GHC==9.2.8
                   , GHC==9.4.8
                   , GHC==9.6.6
@@ -29,10 +31,14 @@ common lang
   default-extensions:
       DerivingStrategies
       DisambiguateRecordFields
+      RoleAnnotations
+      TypeFamilies
 
 library
   import:
       lang
+  other-extensions:
+      CApiFFI
   exposed-modules:
       HsBindgen
       HsBindgen.Preprocessor
@@ -42,6 +48,9 @@ library
       HsBindgen.Annotation
       HsBindgen.C
       HsBindgen.Clang
+      HsBindgen.Clang.LowLevel
+      HsBindgen.Clang.Tutorial
+      HsBindgen.Clang.Util
       HsBindgen.Spec.Resolved
   hs-source-dirs:
       src
@@ -50,10 +59,19 @@ library
     , haskell-src-meta >= 0.8  && < 0.9
     , template-haskell >= 2.18 && < 2.23
 
+  -- @libclang@
+  --
   -- TODO: <https://github.com/llvm/llvm-project/issues/9777>
   -- It seems @libclang@ does not support @pkg-config@.
+
   extra-libraries:
       clang
+  c-sources:
+      cbits/clang_wrappers.c
+  include-dirs:
+      cbits
+  cc-options:
+      -Wall
 
 executable hs-bindgen
   import:

hs-bindgen/src/HsBindgen/Annotation.hs

@@ -21,6 +21,13 @@ module HsBindgen.Annotation (
 -------------------------------------------------------------------------------}
 
 -- | Syntax tree annotation
+--
+-- TODO: <https://github.com/well-typed/hs-bindgen/issues/23>
+-- We should use this explain tool decisions (when generating high-level API).
+--
+-- TODO: <https://github.com/well-typed/hs-bindgen/issues/74>
+-- We should reference the relevant part of the C header here (including line
+-- numbers).
 data Ann = Ann {
     }
 

hs-bindgen/src/HsBindgen/Clang.hs

@@ -1,7 +1,4 @@
--- | Bindings to @libclang@
---
--- The goal of this module is not to be a complete set of bindings for all of
--- @libclang@, but rather only to the parts that we need.
+-- | High-level bindings to @libclang@
 --
 -- Intended for qualified import.
 --