Fix a bug where user modules couldn't resolve builtin functions

compiler/compiler_module.go

@@ -77,6 +77,10 @@ func (c *Compiler) doCompileModule(moduleName string, src []byte) (*objects.Comp
 	}
 
 	symbolTable := NewSymbolTable()
+	for idx, fn := range objects.Builtins {
+		symbolTable.DefineBuiltin(idx, fn.Name)
+	}
+
 	globals := make(map[string]int)
 
 	moduleCompiler := c.fork(moduleName, symbolTable)

docs/interoperability.md

@@ -145,6 +145,8 @@ s.DisableBuiltinFunction("print")
 _, err := s.Run() // compile error 
 ```
 
+Note that when a script is being added to another script as a module (via `Script.AddModule`), it does not inherit the disabled builtin function list from the main script.  
+
 #### Script.DisableStdModule(name string)
 
 DisableStdModule disables a [standard library](https://github.com/d5/tengo/blob/master/docs/stdlib.md) module. Compile will report a compile-time error if the code tries to import the module with the given name.
@@ -157,6 +159,8 @@ s.DisableStdModule("exec")
 _, err := s.Run() // compile error 
 ```
 
+Note that when a script is being added to another script as a module (via `Script.AddModule`), it does not inherit the disabled standard module list from the main script.
+
 #### Script.SetUserModuleLoader(loader compiler.ModuleLoader)
 
 SetUserModuleLoader replaces the default user-module loader of the compiler, which tries to read the source from a local file.  
@@ -173,6 +177,8 @@ s.SetUserModuleLoader(func(moduleName string) ([]byte, error) {
 })
 ```
 
+Note that when a script is being added to another script as a module (via `Script.AddModule`), it does not inherit the module loader from the main script.
+
 ## Compiler and VM
 
 Although it's not recommended, you can directly create and run the Tengo [Parser](https://godoc.org/github.com/d5/tengo/compiler/parser#Parser), [Compiler](https://godoc.org/github.com/d5/tengo/compiler#Compiler), and [VM](https://godoc.org/github.com/d5/tengo/runtime#VM) for yourself instead of using Scripts and Script Variables. It's a bit more involved as you have to manage the symbol tables and global variables between them, but, basically that's what Script and Script Variable is doing internally.

runtime/vm_module_test.go

@@ -126,4 +126,9 @@ if !is_error(cmd) {
 	expectWithUserModules(t, `m1 := import("mod1"); m1.a.b = 5; out = m1.a.b`, 5, map[string]string{
 		"mod1": `a := {b: 3}`,
 	})
+
+	// make sure module has same builtin functions
+	expectWithUserModules(t, `out = import("mod1").a`, "int", map[string]string{
+		"mod1": `a := func() { return type_name(0) }()`,
+	})
 }