Make stdio a feature (#5420)

Cargo.toml

@@ -10,9 +10,10 @@ repository.workspace = true
 license.workspace = true
 
 [features]
-default = ["threading", "stdlib", "importlib"]
+default = ["threading", "stdlib", "stdio", "importlib"]
 importlib = ["rustpython-vm/importlib"]
 encodings = ["rustpython-vm/encodings"]
+stdio = ["rustpython-vm/stdio"]
 stdlib = ["rustpython-stdlib", "rustpython-pylib", "encodings"]
 flame-it = ["rustpython-vm/flame-it", "flame", "flamescope"]
 freeze-stdlib = ["stdlib", "rustpython-vm/freeze-stdlib", "rustpython-pylib?/freeze-stdlib"]

vm/Cargo.toml

@@ -10,7 +10,8 @@ repository.workspace = true
 license.workspace = true
 
 [features]
-default = ["compiler", "wasmbind"]
+default = ["compiler", "wasmbind", "stdio"]
+stdio = []
 importlib = []
 encodings = ["importlib"]
 vm-tracing-logging = []

vm/src/vm/mod.rs

@@ -14,6 +14,8 @@ mod vm_new;
 mod vm_object;
 mod vm_ops;
 
+#[cfg(not(feature = "stdio"))]
+use crate::builtins::PyNone;
 use crate::{
     AsObject, Py, PyObject, PyObjectRef, PyPayload, PyRef, PyResult,
     builtins::{
@@ -301,7 +303,8 @@ impl VirtualMachine {
             #[cfg(any(not(target_arch = "wasm32"), target_os = "wasi"))]
             {
                 let io = import::import_builtin(self, "_io")?;
-                let set_stdio = |name, fd, write| {
+                #[cfg(feature = "stdio")]
+                let make_stdio = |name, fd, write| {
                     let buffered_stdio = self.state.settings.buffered_stdio;
                     let unbuffered = write && !buffered_stdio;
                     let buf = crate::stdlib::io::open(
@@ -332,7 +335,13 @@ impl VirtualMachine {
                     )?;
                     let mode = if write { "w" } else { "r" };
                     stdio.set_attr("mode", self.ctx.new_str(mode), self)?;
+                    Ok(stdio)
+                };
+                #[cfg(not(feature = "stdio"))]
+                let make_stdio = |_name, _fd, _write| Ok(PyNone.into_pyobject(self));
 
+                let set_stdio = |name, fd, write| {
+                    let stdio = make_stdio(name, fd, write)?;
                     let dunder_name = self.ctx.intern_str(format!("__{name}__"));
                     self.sys_module.set_attr(
                         dunder_name, // e.g. __stdin__