From 5d17b2777088a0ffc97e6383b22dd39173319a0e Mon Sep 17 00:00:00 2001
From: Chris Smowton <smowton@github.com>
Date: Mon, 30 Nov 2020 19:10:58 +0000
Subject: [PATCH] Note that `fmt.Errorf` returns non-nil

This enables recognising more guarding functions that return nil/non-nil conditional on a barrier guard.
---
 ql/src/semmle/go/dataflow/internal/DataFlowUtil.qll | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/ql/src/semmle/go/dataflow/internal/DataFlowUtil.qll b/ql/src/semmle/go/dataflow/internal/DataFlowUtil.qll
index a551496cfb5..13c536a7a48 100644
--- a/ql/src/semmle/go/dataflow/internal/DataFlowUtil.qll
+++ b/ql/src/semmle/go/dataflow/internal/DataFlowUtil.qll
@@ -1285,6 +1285,8 @@ private predicate certainlyReturnsNonNil(Function f, FunctionOutput output) {
   (
     f.hasQualifiedName("errors", "New")
     or
+    f.hasQualifiedName("fmt", "Errorf")
+    or
     f in [Builtin::new(), Builtin::make()]
     or
     exists(FuncDecl fd | fd = f.getFuncDecl() |