pcb_parser.cpp: allows 0 width line thickness for circles in custom shaped pads.

the commit 1100ccb032 broke DRAWSEGMENT filled circles (line width = 0) used only in custom pads.

Fixes: lp:1792791
https://bugs.launchpad.net/kicad/+bug/1792791

pcbnew/pcb_parser.cpp

@@ -2,7 +2,7 @@
  * This program source code file is part of KiCad, a free EDA CAD application.
  *
  * Copyright (C) 2012 CERN
- * Copyright (C) 2012-2017 KiCad Developers, see AUTHORS.txt for contributors.
+ * Copyright (C) 2012-2018 KiCad Developers, see AUTHORS.txt for contributors.
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
@@ -1375,7 +1375,7 @@ void PCB_PARSER::parseNETCLASS()
 }
 
 
-DRAWSEGMENT* PCB_PARSER::parseDRAWSEGMENT()
+DRAWSEGMENT* PCB_PARSER::parseDRAWSEGMENT( bool aAllowCirclesZeroWidth )
 {
     wxCHECK_MSG( CurTok() == T_gr_arc || CurTok() == T_gr_circle || CurTok() == T_gr_curve ||
                  CurTok() == T_gr_line || CurTok() == T_gr_poly, NULL,
@@ -1539,7 +1539,9 @@ DRAWSEGMENT* PCB_PARSER::parseDRAWSEGMENT()
     // Only filled polygons may have a zero-line width
     // This is not permitted in KiCad but some external tools generate invalid
     // files.
-    if( segment->GetShape() != S_POLYGON && segment->GetWidth() == 0 )
+    // However in custom pad shapes, zero-line width is allowed for filled circles
+    if( segment->GetShape() != S_POLYGON && segment->GetWidth() == 0 &&
+        !( segment->GetShape() == S_CIRCLE && aAllowCirclesZeroWidth ) )
         segment->SetWidth( Millimeter2iu( DEFAULT_LINE_WIDTH ) );
 
     return segment.release();
@@ -2588,7 +2590,8 @@ D_PAD* PCB_PARSER::parseD_PAD( MODULE* aParent )
                     break;
 
                 case T_gr_circle:
-                    dummysegm = parseDRAWSEGMENT();
+                    dummysegm = parseDRAWSEGMENT( true );   // Circles with 0 thickness are allowed
+                                                            // ( filled circles )
                     pad->AddPrimitive( dummysegm->GetCenter(), dummysegm->GetRadius(),
                                         dummysegm->GetWidth() );
                     break;

pcbnew/pcb_parser.h

@@ -2,7 +2,7 @@
  * This program source code file is part of KiCad, a free EDA CAD application.
  *
  * Copyright (C) 2012 CERN
- * Copyright (C) 2012-2016 KiCad Developers, see AUTHORS.txt for contributors.
+ * Copyright (C) 2012-2018 KiCad Developers, see AUTHORS.txt for contributors.
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
@@ -113,7 +113,11 @@ class PCB_PARSER : public PCB_LEXER
     void parseNETINFO_ITEM();
     void parseNETCLASS();
 
-    DRAWSEGMENT*    parseDRAWSEGMENT();
+    /** Read a DRAWSEGMENT description.
+     * @param aAllowCirclesZeroWidth = true to allow items with 0 width
+     * Only used in custom pad shapes for filled circles.
+     */
+    DRAWSEGMENT*    parseDRAWSEGMENT( bool aAllowCirclesZeroWidth = false );
     TEXTE_PCB*      parseTEXTE_PCB();
     DIMENSION*      parseDIMENSION();