From 212449bc231047571ab27af0d1ae112ed0ffea47 Mon Sep 17 00:00:00 2001
From: Marc Tiehuis <marctiehuis@gmail.com>
Date: Wed, 6 Jun 2018 22:41:55 +1200
Subject: [PATCH] Fix Log2Int type construction

The following case for example, would previously fail:

    const a = u24(1) << Log2Int(u24)(22);
---
 std/math/index.zig | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/std/math/index.zig b/std/math/index.zig
index 33bc1082f7..a118f3ed47 100644
--- a/std/math/index.zig
+++ b/std/math/index.zig
@@ -306,7 +306,14 @@ test "math.rotl" {
 }
 
 pub fn Log2Int(comptime T: type) type {
-    return @IntType(false, log2(T.bit_count));
+    // comptime ceil log2
+    comptime var count: usize = 0;
+    comptime var s = T.bit_count - 1;
+    inline while (s != 0) : (s >>= 1) {
+        count += 1;
+    }
+
+    return @IntType(false, count);
 }
 
 test "math overflow functions" {