fix: Host Functions of PHP 7.4 (#23)

Fixes issue #22 that causes host
functions with arguments to not work on PHP 7.4.
See issue for context.

.github/workflows/ci.yaml

@@ -13,7 +13,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest]
-        php: ['8.3']
+        php: ['8.3', '7.4']
     steps:
       - name: Checkout sources
         uses: actions/checkout@v3
@@ -28,4 +28,4 @@ jobs:
           fail-fast: true
       - name: Test PHP SDK
         run: |
-          make test
+          make test

Makefile

@@ -4,4 +4,4 @@ prepare:
 	composer install
 
 test: prepare
-	php vendor/bin/phpunit ./tests --display-deprecations --display-warnings
+	php vendor/bin/phpunit ./tests

composer.json

@@ -49,6 +49,6 @@
   "scripts": {},
   "scripts-descriptions": {},
   "require-dev": {
-    "phpunit/phpunit": "^10"
+    "phpunit/phpunit": "^9"
   }
 }

src/HostFunction.php

@@ -15,6 +15,16 @@ class ExtismValType
     public const V128 = 4;
     public const FUNC_REF = 5;
     public const EXTERN_REF = 6;
+
+    public const VAL_TYPE_MAP = [
+        0 => 'ExtismValType_I32',
+        1 => 'ExtismValType_I64',
+        2 => 'ExtismValType_F32',
+        3 => 'ExtismValType_F64',
+        4 => 'ExtismValType_V128',
+        5 => 'ExtismValType_Func_Ref',
+        6 => 'ExtismValType_Extern_Ref',
+    ];
 }
 
 class HostFunction
@@ -52,13 +62,15 @@ function __construct(string $name, array $inputTypes, array $outputTypes, callab
         $inputs = [];
 
         for ($i = 0; $i < count($inputTypes); $i++) {
-            $inputs[$i] = $this->lib->ffi->cast("ExtismValType", $inputTypes[$i]);
+            $enum = ExtismValType::VAL_TYPE_MAP[$inputTypes[$i]];
+            $inputs[$i] = $this->lib->ffi->$enum;
         }
 
         $outputs = [];
 
         for ($i = 0; $i < count($outputTypes); $i++) {
-            $outputs[$i] = $this->lib->ffi->cast("ExtismValType", $outputTypes[$i]);
+            $enum = ExtismValType::VAL_TYPE_MAP[$outputTypes[$i]];
+            $outputs[$i] = $this->lib->ffi->$enum;
         }
 
         $func = function ($handle, $inputs, $n_inputs, $outputs, $n_outputs, $data) use ($callback, $lib, $arguments, $offset) {