Refactor: Introduce a constant for iconv errors

There's no universal system for error handling in place yet, but since selene can't parse LuaJIT's ULL syntax extension, might as well move this constant to C++ already.

Runtime/Bindings/FFI/iconv/iconv.lua

@@ -7,9 +7,7 @@ local ffi_string = ffi.string
 local tonumber = tonumber
 local tostring = tostring
 
-local iconv = {
-	ERROR_CONVERSION_FAILED = ffi.cast("size_t", -1ULL),
-}
+local iconv = {}
 
 iconv.cdefs = [[
 typedef void* iconv_t;
@@ -24,6 +22,9 @@ struct static_iconv_exports_table {
 	iconv_t (*iconv_open)(const char* input_encoding, const char* output_encoding);
 	int (*iconv_close)(iconv_t conversion_descriptor);
 	size_t (*iconv)(iconv_t conversion_descriptor, char** input, size_t* input_size, char** output, size_t* output_size);
+
+	// Shared constants
+	size_t CHARACTER_CONVERSION_FAILED;
 };
 
 ]]

Runtime/Bindings/FFI/iconv/iconv_exports.h

@@ -9,4 +9,7 @@ struct static_iconv_exports_table {
 	iconv_t (*iconv_open)(const char* input_encoding, const char* output_encoding);
 	int (*iconv_close)(iconv_t conversion_descriptor);
 	size_t (*iconv)(iconv_t conversion_descriptor, char** input, size_t* input_size, char** output, size_t* output_size);
+
+	// Shared constants
+	size_t CHARACTER_CONVERSION_FAILED;
 };

Runtime/Bindings/FFI/iconv/iconv_ffi.cpp

@@ -18,7 +18,7 @@ iconv_result_t iconv_convert(char* input, size_t input_length, const char* input
 	size_t num_input_bytes_left = input_length;
 
 	iconv_t conversion_descriptor = iconv_open(output_encoding, input_encoding);
-	if(conversion_descriptor == (iconv_t)-1) {
+	if(reinterpret_cast<size_t>(conversion_descriptor) == iconv_ffi::CHARACTER_CONVERSION_FAILED) {
 		result.message = strerror(errno);
 		result.status_code = errno;
 		result.num_bytes_written = 0;
@@ -53,6 +53,9 @@ namespace iconv_ffi {
 			.iconv_open = &iconv_open,
 			.iconv_close = &iconv_close,
 			.iconv = &iconv,
+
+			// Shared constants
+			.CHARACTER_CONVERSION_FAILED = CHARACTER_CONVERSION_FAILED,
 		};
 
 		return &exports;

Runtime/Bindings/FFI/iconv/iconv_ffi.hpp

@@ -7,5 +7,7 @@
 #include "iconv_exports.h"
 
 namespace iconv_ffi {
+	constexpr std::size_t CHARACTER_CONVERSION_FAILED = static_cast<size_t>(-1);
+
 	void* getExportsTable();
 }

Tests/BDD/iconv-library.spec.lua

@@ -88,21 +88,21 @@ describe("iconv", function()
 
 			it("should indicate an error if the requested conversion isn't supported", function()
 				local descriptor = iconv.bindings.iconv_open("Not-a-real-encoding", "UTF-8")
-				assertEquals(ffi.cast("size_t", descriptor), iconv.ERROR_CONVERSION_FAILED)
+				assertEquals(ffi.cast("size_t", descriptor), iconv.bindings.CHARACTER_CONVERSION_FAILED)
 				iconv.bindings.iconv_close(descriptor)
 			end)
 
 			it("should return a valid handle if the conversion is supported", function()
 				local descriptor = iconv.bindings.iconv_open("CP949", "UTF-8")
-				assertFalse(ffi.cast("size_t", descriptor) == iconv.ERROR_CONVERSION_FAILED)
+				assertFalse(ffi.cast("size_t", descriptor) == iconv.bindings.CHARACTER_CONVERSION_FAILED)
 				iconv.bindings.iconv_close(descriptor)
 			end)
 		end)
 
 		describe("iconv", function()
 			it("should be able to convert Windows encodings to UTF-8", function()
 				local descriptor = iconv.bindings.iconv_open("UTF-8", "CP949")
-				assert(descriptor ~= iconv.ERROR_CONVERSION_FAILED, "Failed to create conversion descriptor")
+				assert(descriptor ~= iconv.bindings.CHARACTER_CONVERSION_FAILED, "Failed to create conversion descriptor")
 
 				local input = "\192\175\192\250\192\206\197\205\198\228\192\204\189\186"
 				local inputSize = ffi.new("size_t[1]", #input)
@@ -114,7 +114,7 @@ describe("iconv", function()
 				local outputRef = ffi.new("char*[1]", outputBuffer)
 
 				local result = iconv.bindings.iconv(descriptor, inputRef, inputSize, outputRef, outputSize)
-				assert(result ~= iconv.ERROR_CONVERSION_FAILED, "Conversion failed")
+				assert(result ~= iconv.bindings.CHARACTER_CONVERSION_FAILED, "Conversion failed")
 
 				local convertedSize = 256 - outputSize[0]
 				local converted = ffi.string(outputBuffer, convertedSize)