From 3465fe3e50a6e8ee0cfd399f33ff80c6ecfe0cc7 Mon Sep 17 00:00:00 2001
From: Seth Hillbrand <seth@kipro-pcb.com>
Date: Fri, 20 Jan 2023 16:43:47 -0800
Subject: [PATCH] Allow variable recursion

Simple recursion of variable expansion allows for multiple use cases in
portability of designs.  This also includes basic prevention of
recursion loops

Fixes https://gitlab.com/kicad/code/kicad/issues/10398
---
 common/common.cpp | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/common/common.cpp b/common/common.cpp
index f553986d53..5d2c923c49 100644
--- a/common/common.cpp
+++ b/common/common.cpp
@@ -115,8 +115,15 @@ wxString ExpandTextVars( const wxString& aSource,
 //
 // Stolen from wxExpandEnvVars and then heavily optimized
 //
-wxString KIwxExpandEnvVars( const wxString& str, const PROJECT* aProject )
+wxString KIwxExpandEnvVars( const wxString& str, const PROJECT* aProject, std::set<wxString>* aSet = nullptr )
 {
+    // If the same string is inserted twice, we have a loop
+    if( aSet )
+    {
+        if( auto [ _, result ] = aSet->insert( str ); !result )
+            return str;
+    }
+
     size_t strlen = str.length();
 
     wxString strResult;
@@ -278,6 +285,13 @@ wxString KIwxExpandEnvVars( const wxString& str, const PROJECT* aProject )
         }
     }
 
+    std::set<wxString> loop_check;
+    auto first_pos = strResult.find_first_of( wxS( "{(%" ) );
+    auto last_pos = strResult.find_last_of( wxS( "})%" ) );
+
+    if( first_pos != strResult.npos && last_pos != strResult.npos && first_pos != last_pos )
+        strResult = KIwxExpandEnvVars( strResult, aProject, aSet ? aSet : &loop_check );
+
     return strResult;
 }