make console optional on Windows

qt/package/Cargo.lock

@@ -17,9 +17,12 @@ version = "0.1.0"
 dependencies = [
  "embed-resource",
  "jemallocator",
+ "libc",
+ "libc-stdhandle",
  "mimalloc",
  "pyembed",
  "snmalloc-rs",
+ "winapi",
 ]
 
 [[package]]
@@ -204,6 +207,16 @@ version = "0.2.105"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "869d572136620d55835903746bcb5cdc54cb2851fd0aeec53220b4bb65ef3013"
 
+[[package]]
+name = "libc-stdhandle"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6dac2473dc28934c5e0b82250dab231c9d3b94160d91fe9ff483323b05797551"
+dependencies = [
+ "cc",
+ "libc",
+]
+
 [[package]]
 name = "libmimalloc-sys"
 version = "0.1.22"

qt/package/Cargo.toml

@@ -4,7 +4,10 @@ version = "0.1.0"
 build = "build.rs"
 edition = "2018"
 
-# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+[target.'cfg(windows)'.dependencies]
+winapi = {version = "0.3", features = ["wincon"]}
+libc = "0.2"
+libc-stdhandle = "=0.1.0"
 
 [dependencies.pyembed]
 git = "https://github.com/ankitects/PyOxidizer.git"

qt/package/rustfmt.toml

@@ -0,0 +1,4 @@
+# this is not supported on stable Rust, and is ignored by the Bazel rules; it is only
+# useful for manual invocation with 'cargo +nightly fmt'
+imports_granularity = "Crate"
+group_imports = "StdExternalCrate"

qt/package/src/anki.rs

@@ -0,0 +1,35 @@
+// Copyright: Ankitects Pty Ltd and contributors
+// License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
+
+pub(super) fn init() {
+    #[cfg(target_os = "windows")]
+    attach_console();
+
+    println!("Anki starting...");
+}
+
+/// If parent process has a console (eg cmd.exe), redirect our output there.
+#[cfg(target_os = "windows")]
+fn attach_console() {
+    use std::ffi::CString;
+
+    use libc_stdhandle::*;
+    use winapi::um::wincon;
+
+    let console_attached = unsafe { wincon::AttachConsole(wincon::ATTACH_PARENT_PROCESS) };
+    if console_attached == 0 {
+        return;
+    }
+
+    let conin = CString::new("CONIN$").unwrap();
+    let conout = CString::new("CONOUT$").unwrap();
+    let r = CString::new("r").unwrap();
+    let w = CString::new("w").unwrap();
+
+    // Python uses the CRT for I/O, and it requires the descriptors are reopened.
+    unsafe {
+        libc::freopen(conin.as_ptr(), r.as_ptr(), stdin());
+        libc::freopen(conout.as_ptr(), w.as_ptr(), stdout());
+        libc::freopen(conout.as_ptr(), w.as_ptr(), stderr());
+    }
+}

qt/package/src/main.rs

@@ -3,7 +3,9 @@
 // License, v. 2.0. If a copy of the MPL was not distributed with this
 // file, You can obtain one at https://mozilla.org/MPL/2.0/.
 
-#![windows_subsystem = "console"]
+#![windows_subsystem = "windows"]
+
+mod anki;
 
 use pyembed::{MainPythonInterpreter, OxidizedPythonInterpreterConfig};
 
@@ -14,7 +16,7 @@ static GLOBAL: jemallocator::Jemalloc = jemallocator::Jemalloc;
 include!(env!("DEFAULT_PYTHON_CONFIG_RS"));
 
 fn main() {
-    println!("Anki starting...");
+    anki::init();
 
     let exit_code = {
         let config: OxidizedPythonInterpreterConfig = default_python_config();

qt/package/win/anki-console.bat

@@ -0,0 +1,5 @@
+@echo off
+anki
+pause
+
+