Merge branch 'master' into feat/config-request-timeout

Author: gmelodie

CHANGELOG.md

@@ -30,6 +30,20 @@ All notable changes to this project are documented in this file.
   a `"timeout = <ms>"` spec (e.g. `{.ffi: "timeout = 30000".}`), parsed like the
   `abi = ...` spec; runtime-only, codegen ignores it
   ([#93](https://github.com/logos-messaging/nim-ffi/issues/93)).
+- **C binding generator** (`-d:targetLang=c`): emits a header-only C binding
+  (`<lib>.h`) plus a `CMakeLists.txt`, alongside the existing Rust / C++ / CDDL
+  backends. Requests/responses travel as CBOR using the same vendored TinyCBOR
+  the C++ backend uses. C has no generics or overloading, so each `seq[T]` /
+  `Option[T]` is monomorphised into its own struct + encode/decode/free triple.
+  The high-level `<lib>_ctx_*` API is asynchronous: each method/constructor
+  takes a typed result callback and the binding owns and reclaims all reply
+  data and error strings (valid only for the duration of the callback), so the
+  caller never frees anything — there is no blocking wait and no manual-free
+  contract. Shared codegen helpers were extracted
+  into `ffi/codegen/common.nim` (used by both the C and C++ backends). New
+  `nimble genbindings_c` / `genbindings_c_echo` / `check_bindings_c` /
+  `test_c_e2e` tasks, a `tests/e2e/c` ctest harness, and a
+  `tests/unit/test_c_codegen.nim` unit suite.
 - Per-interaction ABI-format annotations: `declareLibrary` now takes an
   optional `defaultABIFormat` (`"cbor"` default, or `"c"`) that every
   `{.ffi.}` / `{.ffiCtor.}` / `{.ffiDtor.}` / `{.ffiRaw.}` / `{.ffiEvent.}`

examples/echo/c_bindings/CMakeLists.txt

@@ -0,0 +1,47 @@
+cmake_minimum_required(VERSION 3.14)
+project(echo_c_bindings C)
+
+set(CMAKE_C_STANDARD 11)
+set(CMAKE_C_STANDARD_REQUIRED ON)
+
+# ── Locate the repository root (contains ffi.nimble) ─────────────────────────
+set(_search_dir "${CMAKE_CURRENT_SOURCE_DIR}")
+set(REPO_ROOT "")
+foreach(_i RANGE 10)
+    if(EXISTS "${_search_dir}/ffi.nimble")
+        set(REPO_ROOT "${_search_dir}")
+        break()
+    endif()
+    get_filename_component(_search_dir "${_search_dir}" DIRECTORY)
+endforeach()
+if("${REPO_ROOT}" STREQUAL "")
+    message(FATAL_ERROR "Cannot find repo root (no ffi.nimble in any ancestor)")
+endif()
+
+# Build the Nim dylib + vendored TinyCBOR (shared with the C++ backend).
+set(NIM_FFI_LIB echo)
+set(NIM_FFI_SRC ../echo.nim)
+include("${REPO_ROOT}/ffi/codegen/templates/nim_ffi_lib.cmake")
+
+find_package(Threads REQUIRED)
+
+add_library(echo_headers INTERFACE)
+target_include_directories(echo_headers INTERFACE "${CMAKE_CURRENT_SOURCE_DIR}")
+target_link_libraries(echo_headers INTERFACE echo tinycbor Threads::Threads)
+# The generated header is async (no blocking helper), but consumer code that
+# waits on a result callback typically uses nanosleep / pthreads, which need a
+# POSIX feature level that strict `-std=c11` hides. Define it for consumers.
+target_compile_definitions(echo_headers INTERFACE _POSIX_C_SOURCE=200809L)
+
+if(EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/main.c")
+    add_executable(echo_example main.c)
+    target_link_libraries(echo_example PRIVATE echo_headers)
+    add_dependencies(echo_example echo_nim_lib)
+    if(CMAKE_SYSTEM_NAME STREQUAL "Windows")
+        add_custom_command(TARGET echo_example POST_BUILD
+            COMMAND "${CMAKE_COMMAND}" -E copy_if_different
+                "${echo_RUNTIME_LIB}"
+                "$<TARGET_FILE_DIR:echo_example>"
+            COMMENT "Staging echo.dll next to echo_example.exe")
+    endif()
+endif()