Update dependencies and fix build

Author: ircmaxell

Docker/ubuntu-18.04/Dockerfile

@@ -0,0 +1,11 @@
+FROM ircmaxell/php-compiler:18.04-dev
+
+COPY ./ /compiler
+
+WORKDIR /compiler
+
+RUN composer install --no-ansi --no-dev --no-interaction --no-progress --no-scripts --optimize-autoloader
+
+ENTRYPOINT ["php", "/compiler/bin/jit.php"]
+
+CMD ["-r", "echo \"Hello World\n\";"]

Docker/yaypatch.patch

@@ -14,6 +14,10 @@ composer-update:
 shell:
 	docker run -it --cap-add=SYS_PTRACE --security-opt seccomp=unconfined -v $(shell pwd):/compiler ircmaxell/php-compiler:16.04-dev /bin/bash
 
+.PHONY: shell-18
+shell-18:
+	docker run -it --cap-add=SYS_PTRACE --security-opt seccomp=unconfined -v $(shell pwd):/compiler ircmaxell/php-compiler:18.04-dev /bin/bash
+
 .PHONY: docker-build-clean
 docker-build-clean:
 	docker build --no-cache -t ircmaxell/php-compiler:16.04-dev Docker/dev/ubuntu-16.04
@@ -24,9 +28,15 @@ docker-build:
 	docker build -t ircmaxell/php-compiler:16.04-dev Docker/dev/ubuntu-16.04
 	docker build --no-cache -t ircmaxell/php-compiler:16.04 -f Docker/ubuntu-16.04/Dockerfile .
 
+.PHONY: docker-build-clean-18
+docker-build-clean-18:
+	docker build --no-cache -t ircmaxell/php-compiler:18.04-dev Docker/dev/ubuntu-18.04
+	docker build --no-cache -t ircmaxell/php-compiler:18.04 -f Docker/ubuntu-18.04/Dockerfile .
+
 .PHONY: docker-build-18
 docker-build-18:
 	docker build -t ircmaxell/php-compiler:18.04-dev Docker/dev/ubuntu-18.04
+	docker build --no-cache -t ircmaxell/php-compiler:18.04 -f Docker/ubuntu-18.04/Dockerfile .
 
 .PHONY: benchmark
 benchmark: rebuild-changed
@@ -58,3 +68,7 @@ phan:
 .PHONY: test
 test: rebuild-changed
 	docker run -v $(shell pwd):/compiler ircmaxell/php-compiler:16.04-dev php vendor/bin/phpunit
+
+.PHONY: test-18
+test-18: rebuild-changed
+	docker run -v $(shell pwd):/compiler ircmaxell/php-compiler:18.04-dev php vendor/bin/phpunit

Makefile

@@ -63,7 +63,7 @@ public function iterate(bool $resolveIndirect = false): \Traversable {
         }
     }
 
-    public function findVariable(Variable $index, bool $forWrite): Variable {
+    public function findVariable(Variable $index, bool $forWrite): ?Variable {
         switch ($index->type) {
             case Variable::TYPE_INTEGER:
                 $result = $this->findIndex($index->toInt());