Consider a bus entry hitting a wire corner or tee to be dot-worthy

This doesn't change the connectivity, it just makes putting the
dot more closely match what the connectivity already does.

Fixes: https://gitlab.com/kicad/code/kicad/-/issues/18046

eeschema/junction_helpers.cpp

@@ -13,10 +13,11 @@ POINT_INFO JUNCTION_HELPERS::AnalyzePoint( const EE_RTREE& aItems, const VECTOR2
         BUSES
     };
 
-    POINT_INFO info {};
+    POINT_INFO info{};
     info.hasBusEntry = false;
     info.hasExplicitJunctionDot = false;
     info.isJunction = false;
+    info.hasBusEntryToMultipleWires = false;
 
     bool                         breakLines[2] = { false };
     std::unordered_set<int>      exitAngles[2];
@@ -106,6 +107,17 @@ POINT_INFO JUNCTION_HELPERS::AnalyzePoint( const EE_RTREE& aItems, const VECTOR2
         }
     }
 
+    if( info.hasBusEntry )
+    {
+        // The bus entry and one wire is 2 wires, and the one entry is exactly one bus
+        // Any more wires must be multiple wires, but any more buses means a wire
+        // crossing at the bus entry root.
+        info.hasBusEntryToMultipleWires =
+                exitAngles[WIRES].size() > 2 && exitAngles[BUSES].size() == 1;
+    }
+
+    // Any three things of the same type is a junction of some sort
     info.isJunction = exitAngles[WIRES].size() >= 3 || exitAngles[BUSES].size() >= 3;
+
     return info;
 }

eeschema/junction_helpers.h

@@ -10,9 +10,14 @@ namespace JUNCTION_HELPERS
 */
 struct POINT_INFO
 {
+    ///< True if the point has 3+ wires and/or 3+ buses meeting there
     bool isJunction;
+    ///< True if there is already junction dot at the point
     bool hasExplicitJunctionDot;
+    ///< True if there is a bus entry at the point (either end)
     bool hasBusEntry;
+    ///< True if there is a bus entry at the point and it connects to more than one wire
+    bool hasBusEntryToMultipleWires;
 };
 
 /**

eeschema/sch_screen.cpp

@@ -488,7 +488,7 @@ bool SCH_SCREEN::IsExplicitJunction( const VECTOR2I& aPosition ) const
     const JUNCTION_HELPERS::POINT_INFO info =
             JUNCTION_HELPERS::AnalyzePoint( Items(), aPosition, false );
 
-    return info.isJunction && !info.hasBusEntry;
+    return info.isJunction && ( !info.hasBusEntry || info.hasBusEntryToMultipleWires );
 }
 
 
@@ -497,7 +497,8 @@ bool SCH_SCREEN::IsExplicitJunctionNeeded( const VECTOR2I& aPosition ) const
     const JUNCTION_HELPERS::POINT_INFO info =
             JUNCTION_HELPERS::AnalyzePoint( Items(), aPosition, false );
 
-    return info.isJunction && !info.hasBusEntry && !info.hasExplicitJunctionDot;
+    return info.isJunction && ( !info.hasBusEntry || info.hasBusEntryToMultipleWires )
+           && !info.hasExplicitJunctionDot;
 }
 
 
@@ -506,7 +507,7 @@ bool SCH_SCREEN::IsExplicitJunctionAllowed( const VECTOR2I& aPosition ) const
     const JUNCTION_HELPERS::POINT_INFO info =
             JUNCTION_HELPERS::AnalyzePoint( Items(), aPosition, true );
 
-    return info.isJunction && !info.hasBusEntry;
+    return info.isJunction && (!info.hasBusEntry || info.hasBusEntryToMultipleWires );
 }
 
 

qa/tests/eeschema/test_junction_helpers.cpp

@@ -109,6 +109,8 @@ BOOST_AUTO_TEST_CASE( WireTee )
     const POINT_INFO info = AnalyzePoint( items, { 0, 0 }, false );
 
     BOOST_CHECK( info.isJunction );
+    BOOST_CHECK( !info.hasBusEntry );
+    BOOST_CHECK( !info.hasBusEntryToMultipleWires );
 }
 
 BOOST_AUTO_TEST_CASE( BusEntryOnBus )
@@ -139,6 +141,8 @@ BOOST_AUTO_TEST_CASE( BusEntryOnBus )
     const POINT_INFO info_end = AnalyzePoint( items, { BE_SIZE, BE_SIZE }, false );
     BOOST_CHECK( !info_end.isJunction );
     BOOST_CHECK( info_end.hasBusEntry );
+    // There is no wire here
+    BOOST_CHECK( !info_end.hasBusEntryToMultipleWires );
 }
 
 BOOST_AUTO_TEST_CASE( BusEntryToWire )
@@ -155,6 +159,8 @@ BOOST_AUTO_TEST_CASE( BusEntryToWire )
     const POINT_INFO info = AnalyzePoint( items, { BE_SIZE, BE_SIZE }, false );
     BOOST_CHECK( !info.isJunction );
     BOOST_CHECK( info.hasBusEntry );
+    // This is a single wire to a bus entry, not multiple
+    BOOST_CHECK( !info.hasBusEntryToMultipleWires );
 }
 
 BOOST_AUTO_TEST_CASE( WireDirectToBus )
@@ -169,6 +175,8 @@ BOOST_AUTO_TEST_CASE( WireDirectToBus )
     const POINT_INFO info = AnalyzePoint( items, { 0, 0 }, false );
     BOOST_CHECK( !info.isJunction );
     BOOST_CHECK( !info.hasBusEntry );
+    // It's a single wire, and not a bus entry
+    BOOST_CHECK( !info.hasBusEntryToMultipleWires );
 }
 
 BOOST_AUTO_TEST_CASE( WireCrossingBus )
@@ -188,13 +196,14 @@ BOOST_AUTO_TEST_CASE( WireCrossingBus )
     // Two wires and two buses meet, which isn't a junction
     BOOST_CHECK( !info.isJunction );
     BOOST_CHECK( !info.hasBusEntry );
+    BOOST_CHECK( !info.hasBusEntryToMultipleWires );
 }
 
 BOOST_AUTO_TEST_CASE( WireToBusEntryRoot )
 {
     /*
-     *   /--- <-- not a junction (also an ERC error!)
+     *   /--- <-- not a junction
-     * ______________
+     *  _____________
      * ||\
      * || \
      * ||  \
@@ -206,6 +215,8 @@ BOOST_AUTO_TEST_CASE( WireToBusEntryRoot )
     const POINT_INFO info = AnalyzePoint( items, { 0, 0 }, false );
     BOOST_CHECK( !info.isJunction );
     BOOST_CHECK( info.hasBusEntry );
+    // The bus/bus-entry point isn't valid
+    BOOST_CHECK( !info.hasBusEntryToMultipleWires );
 }
 
 BOOST_AUTO_TEST_CASE( WireCrossingBusEntryRoot )
@@ -228,6 +239,8 @@ BOOST_AUTO_TEST_CASE( WireCrossingBusEntryRoot )
     // Three buses meet here, so this is a junction
     BOOST_CHECK( info.isJunction );
     BOOST_CHECK( info.hasBusEntry );
+    // There are multiple wires but they don't count here
+    BOOST_CHECK( !info.hasBusEntryToMultipleWires );
 }
 
 BOOST_AUTO_TEST_CASE( WireCornerToBusEntry )
@@ -250,6 +263,31 @@ BOOST_AUTO_TEST_CASE( WireCornerToBusEntry )
     const POINT_INFO info = AnalyzePoint( items, { BE_SIZE, BE_SIZE }, false );
     BOOST_CHECK( info.isJunction );
     BOOST_CHECK( info.hasBusEntry );
+    BOOST_CHECK( info.hasBusEntryToMultipleWires );
+}
+
+BOOST_AUTO_TEST_CASE( WireTeeToBusEntry )
+{
+    /*
+    *  ||
+     * ||
+     * ||  |
+     *   \ |  /--- junction here
+     *    \| /
+     *     O-------------
+     *     |
+     *     |
+     */
+    items.insert( make_bus( { 0, 0 }, { 0, BE_SIZE } ) );
+    items.insert( make_wire( { BE_SIZE, BE_SIZE }, { 2 * BE_SIZE, BE_SIZE } ) ); // right
+    items.insert( make_wire( { BE_SIZE, BE_SIZE }, { BE_SIZE, 0 } ) );           //up
+    items.insert( make_wire( { BE_SIZE, BE_SIZE }, { BE_SIZE, 2 * BE_SIZE } ) ); // down
+    items.insert( new SCH_BUS_WIRE_ENTRY( { 0, 0 }, false ) );
+
+    const POINT_INFO info = AnalyzePoint( items, { BE_SIZE, BE_SIZE }, false );
+    BOOST_CHECK( info.isJunction );
+    BOOST_CHECK( info.hasBusEntry );
+    BOOST_CHECK( info.hasBusEntryToMultipleWires );
 }
 
 BOOST_AUTO_TEST_CASE( SheetPinToOneWire )