From 09db7ead50ad86c2738f4006735a0dab9b97fbb8 Mon Sep 17 00:00:00 2001
From: Ayke van Laethem <aykevanlaethem@gmail.com>
Date: Sat, 20 Apr 2019 02:42:13 +0200
Subject: [PATCH] cgo: better error message when using an undefined CGo
 function pointer

---
 compiler/compiler.go | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/compiler/compiler.go b/compiler/compiler.go
index e863508d..4c686556 100644
--- a/compiler/compiler.go
+++ b/compiler/compiler.go
@@ -2576,6 +2576,9 @@ func (c *Compiler) parseUnOp(frame *Frame, unop *ssa.UnOp) (llvm.Value, error) {
 			global := c.ir.GetGlobal(unop.X.(*ssa.Global))
 			name := global.LinkName()[:len(global.LinkName())-len("$funcaddr")]
 			fn := c.mod.NamedFunction(name)
+			if fn.IsNil() {
+				return llvm.Value{}, c.makeError(unop.Pos(), "cgo function not found: "+name)
+			}
 			return c.builder.CreateBitCast(fn, c.i8ptrType, ""), nil
 		} else {
 			c.emitNilCheck(frame, x, "deref")