From 7bb67b1fd0ca56a04778083f1a01583d839be9b1 Mon Sep 17 00:00:00 2001
From: Andrew Kelley <superjoe30@gmail.com>
Date: Wed, 6 Apr 2016 14:08:23 -0700
Subject: [PATCH] ability to compare function pointers at compile time

---
 src/analyze.cpp      | 10 ++++++++++
 test/self_hosted.zig |  9 +++++++++
 2 files changed, 19 insertions(+)

diff --git a/src/analyze.cpp b/src/analyze.cpp
index 99f1dac3c..91fbddf71 100644
--- a/src/analyze.cpp
+++ b/src/analyze.cpp
@@ -2902,6 +2902,16 @@ static TypeTableEntry *analyze_bool_bin_op_expr(CodeGen *g, ImportTableEntry *im
     } else if (resolved_type->id == TypeTableEntryIdPureError) {
         bool are_equal = op1_val->data.x_err.err == op2_val->data.x_err.err;
 
+        if (bin_op_type == BinOpTypeCmpEq) {
+            answer = are_equal;
+        } else if (bin_op_type == BinOpTypeCmpNotEq) {
+            answer = !are_equal;
+        } else {
+            zig_unreachable();
+        }
+    } else if (resolved_type->id == TypeTableEntryIdFn) {
+        bool are_equal = (op1_val->data.x_fn == op2_val->data.x_fn);
+
         if (bin_op_type == BinOpTypeCmpEq) {
             answer = are_equal;
         } else if (bin_op_type == BinOpTypeCmpNotEq) {
diff --git a/test/self_hosted.zig b/test/self_hosted.zig
index af3c26e8f..5dffbf9a1 100644
--- a/test/self_hosted.zig
+++ b/test/self_hosted.zig
@@ -522,6 +522,15 @@ fn max(T: type)(a: T, b: T) -> T {
 }
 
 
+#attribute("test")
+fn constant_equal_function_pointers() {
+    const alias = empty_fn;
+    assert(@const_eval(empty_fn == alias));
+}
+
+fn empty_fn() {}
+
+
 fn assert(b: bool) {
     if (!b) unreachable{}
 }