From 7b938767bb18535a870d0460c9f4d9e3d93ab053 Mon Sep 17 00:00:00 2001
From: ominitay <37453713+ominitay@users.noreply.github.com>
Date: Sun, 30 Jan 2022 13:22:49 +0000
Subject: [PATCH] std.os: throw compile error for `argv` on Windows

On Windows, `argv` is not populated by start code, and instead left as undefined. This is problematic, and can lead to incorrect programs compiling, but panicking when trying to access `argv`. This change causes these programs to produce a compile error on Windows instead, which is far preferable to a runtime panic.
---
 lib/std/os.zig | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/lib/std/os.zig b/lib/std/os.zig
index 16a32766dc..d7f60c1e1a 100644
--- a/lib/std/os.zig
+++ b/lib/std/os.zig
@@ -218,9 +218,13 @@ pub const socket_t = if (builtin.os.tag == .windows) windows.ws2_32.SOCKET else
 pub var environ: [][*:0]u8 = undefined;
 
 /// Populated by startup code before main().
-/// Not available on Windows. See `std.process.args`
-/// for obtaining the process arguments.
-pub var argv: [][*:0]u8 = undefined;
+/// Not available on WASI or Windows without libc. See `std.process.argsAlloc`
+/// or `std.process.argsWithAllocator` for a cross-platform alternative.
+pub var argv: [][*:0]u8 = if (builtin.link_libc) undefined else switch (builtin.os.tag) {
+    .windows => @compileError("argv isn't supported on Windows: use std.process.argsAlloc instead"),
+    .wasi => @compileError("argv isn't supported on WASI: use std.process.argsAlloc instead"),
+    else => undefined,
+};
 
 /// To obtain errno, call this function with the return value of the
 /// system function call. For some systems this will obtain the value directly