From 25051832b37bab8d945e6284899a4c916ae00ada Mon Sep 17 00:00:00 2001
From: Andrew Kelley <andrew@ziglang.org>
Date: Tue, 31 Dec 2019 13:13:13 -0500
Subject: [PATCH] std.fmt.format: add helpful compile error for non-tuple args

---
 lib/std/fmt.zig | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/lib/std/fmt.zig b/lib/std/fmt.zig
index f1249afa97..1d64468eb8 100644
--- a/lib/std/fmt.zig
+++ b/lib/std/fmt.zig
@@ -94,6 +94,9 @@ pub fn format(
     args: var,
 ) Errors!void {
     const ArgSetType = @IntType(false, 32);
+    if (@typeInfo(@TypeOf(args)) != .Struct) {
+        @compileError("Expected tuple or struct argument, found " ++ @typeName(@TypeOf(args)));
+    }
     if (args.len > ArgSetType.bit_count) {
         @compileError("32 arguments max are supported per format call");
     }