feat(compiler): Allow compilation of empty programs (#1336)

Author: ospencer

compiler/src/parsing/parser.mly

@@ -712,3 +712,4 @@ toplevel_stmts:
 
 program:
   | opt_eols toplevel_stmts EOF { make_program $2 }
+  | opt_eols EOF { make_program [] }

compiler/test/__snapshots__/basic_functionality.d124f931.0.snapshot

@@ -0,0 +1,39 @@
+basic functionality › nil
+(module
+ (type $none_=>_i32 (func (result i32)))
+ (type $none_=>_none (func))
+ (import \"_grainEnv\" \"mem\" (memory $0 0))
+ (import \"_grainEnv\" \"tbl\" (table $tbl 0 funcref))
+ (import \"_grainEnv\" \"relocBase\" (global $relocBase_0 i32))
+ (import \"_grainEnv\" \"moduleRuntimeId\" (global $moduleRuntimeId_0 i32))
+ (global $GRAIN$TABLE_SIZE i32 (i32.const 0))
+ (elem $elem (global.get $relocBase_0))
+ (export \"memory\" (memory $0))
+ (export \"_gmain\" (func $_gmain))
+ (export \"_start\" (func $_start))
+ (export \"GRAIN$TABLE_SIZE\" (global $GRAIN$TABLE_SIZE))
+ (func $_gmain (result i32)
+  (local $0 i32)
+  (local $1 i32)
+  (local $2 i32)
+  (local $3 i64)
+  (local $4 f32)
+  (local $5 f64)
+  (return
+   (block $cleanup_locals.2 (result i32)
+    (local.set $0
+     (block $compile_block.1 (result i32)
+      (i32.const 1879048190)
+     )
+    )
+    (local.get $0)
+   )
+  )
+ )
+ (func $_start
+  (drop
+   (call $_gmain)
+  )
+ )
+ ;; custom section \"cmi\", size 235
+)

compiler/test/suites/basic_functionality.re

@@ -10,6 +10,7 @@ describe("basic functionality", ({test, testSkip}) => {
   let assertCompileError = makeCompileErrorRunner(test);
   let assertRunError = makeErrorRunner(test_or_skip);
 
+  assertSnapshot("nil", "");
   assertSnapshot("forty", "let x = 40; x");
   assertSnapshot("neg", "-40");
   assertSnapshot("simple_min", "-1073741824");