From 11193d2cdad1bde150586c458bacf65fa3f39fc0 Mon Sep 17 00:00:00 2001
From: Jeff Young <jeff@rokeby.ie>
Date: Sat, 1 Jun 2024 11:37:01 +0100
Subject: [PATCH] Make sure ERC pin-to-pin checks are always in same order.

Comparing U1.pin1 : U2.pin1 will return the same
results as U2.pin1 : U1.pin1, but will result in a
different serialization of any exclusions.

Fixes https://gitlab.com/kicad/code/kicad/-/issues/17004
---
 eeschema/erc/erc.cpp                 | 15 +++++++++++++++
 eeschema/erc/erc_sch_pin_context.cpp |  4 ++--
 eeschema/erc/erc_sch_pin_context.h   |  4 ++--
 3 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/eeschema/erc/erc.cpp b/eeschema/erc/erc.cpp
index d9d01fb2db..8500b65623 100644
--- a/eeschema/erc/erc.cpp
+++ b/eeschema/erc/erc.cpp
@@ -761,6 +761,21 @@ int ERC_TESTER::TestPinToPin()
             }
         }
 
+        std::sort( pins.begin(), pins.end(),
+                   []( const ERC_SCH_PIN_CONTEXT& lhs, const ERC_SCH_PIN_CONTEXT& rhs )
+                   {
+                       int ret = StrNumCmp( lhs.Pin()->GetParentSymbol()->GetRef( &lhs.Sheet() ),
+                                            rhs.Pin()->GetParentSymbol()->GetRef( &rhs.Sheet() ) );
+
+                       if( ret == 0 )
+                           ret = StrNumCmp( lhs.Pin()->GetNumber(), rhs.Pin()->GetNumber() );
+
+                       if( ret == 0 )
+                           ret = lhs < rhs; // Fallback to hash to guarantee deterministic sort
+
+                       return ret < 0;
+                   } );
+
         ERC_SCH_PIN_CONTEXT needsDriver;
         bool                hasDriver = false;
 
diff --git a/eeschema/erc/erc_sch_pin_context.cpp b/eeschema/erc/erc_sch_pin_context.cpp
index 233a6473a4..6373421388 100644
--- a/eeschema/erc/erc_sch_pin_context.cpp
+++ b/eeschema/erc/erc_sch_pin_context.cpp
@@ -30,13 +30,13 @@
 #include <erc/erc_sch_pin_context.h>
 
 
-SCH_PIN* ERC_SCH_PIN_CONTEXT::Pin()
+SCH_PIN* ERC_SCH_PIN_CONTEXT::Pin() const
 {
     return m_pin;
 }
 
 
-SCH_SHEET_PATH& ERC_SCH_PIN_CONTEXT::Sheet()
+const SCH_SHEET_PATH& ERC_SCH_PIN_CONTEXT::Sheet() const
 {
     return m_sheet;
 }
diff --git a/eeschema/erc/erc_sch_pin_context.h b/eeschema/erc/erc_sch_pin_context.h
index 0e2da37f28..244c976c5e 100644
--- a/eeschema/erc/erc_sch_pin_context.h
+++ b/eeschema/erc/erc_sch_pin_context.h
@@ -62,12 +62,12 @@ public:
     /**
      * Get the SCH_PIN for this context.
      */
-    SCH_PIN* Pin();
+    SCH_PIN* Pin() const;
 
     /**
      * Get the #SCH_SHEET_PATH context for the paired #SCH_PIN.
      */
-    SCH_SHEET_PATH& Sheet();
+    const SCH_SHEET_PATH& Sheet() const;
 
     /**
      * Test two pin contexts for equality based on the deterministic hash.