From 28f9230b40ee7aa179705c39616aaf2a5f303b73 Mon Sep 17 00:00:00 2001
From: Andrew Kelley <superjoe30@gmail.com>
Date: Tue, 10 Jul 2018 10:12:08 -0400
Subject: [PATCH] fix crash when calling comptime-known undefined function ptr

closes #880
closes #1212
---
 src/ir.cpp              |  2 ++
 test/compile_errors.zig | 13 +++++++++++++
 2 files changed, 15 insertions(+)

diff --git a/src/ir.cpp b/src/ir.cpp
index 2dc6ddad2c69fb0600458db77dec3946ede92f74..10ce3254fd8d65b3593875549b4b0ae1b3f0741d 100644
--- a/src/ir.cpp
+++ b/src/ir.cpp
@@ -13271,6 +13271,8 @@ static TypeTableEntry *ir_analyze_instruction_call(IrAnalyze *ira, IrInstruction
             return ir_finish_anal(ira, cast_instruction->value.type);
         } else if (fn_ref->value.type->id == TypeTableEntryIdFn) {
             FnTableEntry *fn_table_entry = ir_resolve_fn(ira, fn_ref);
+            if (fn_table_entry == nullptr)
+                return ira->codegen->builtin_types.entry_invalid;
             return ir_analyze_fn_call(ira, call_instruction, fn_table_entry, fn_table_entry->type_entry,
                 fn_ref, nullptr, is_comptime, call_instruction->fn_inline);
         } else if (fn_ref->value.type->id == TypeTableEntryIdBoundFn) {
diff --git a/test/compile_errors.zig b/test/compile_errors.zig
index 1b76c01564866b9c0af6a4cb0da4dcc08e2b2ba7..a6db8d50b4bfd4db933bb193addb18535d59ba80 100644
--- a/test/compile_errors.zig
+++ b/test/compile_errors.zig
@@ -1,6 +1,19 @@
 const tests = @import("tests.zig");
 
 pub fn addCases(cases: *tests.CompileErrorContext) void {
+    cases.add(
+        "use of comptime-known undefined function value",
+        \\const Cmd = struct {
+        \\    exec: fn () void,
+        \\};
+        \\export fn entry() void {
+        \\    const command = Cmd{ .exec = undefined };
+        \\    command.exec();
+        \\}
+    ,
+        ".tmp_source.zig:6:12: error: use of undefined value",
+    );
+
     cases.add(
         "bad @alignCast at comptime",
         \\comptime {
-- 
2.54.0