Add FootprintExists() which can be more careful about FS differences.

(And in particular, MSW's case-insensitive FS.)

Fixes: lp:1835999
* https://bugs.launchpad.net/kicad/+bug/1835999

common/fp_lib_table.cpp

@@ -341,8 +341,11 @@ bool FP_LIB_TABLE::FootprintExists( const wxString& aNickname, const wxString& a
 {
     try
     {
-        std::unique_ptr<MODULE> m( FootprintLoad( aNickname, aFootprintName ) );
+        const FP_LIB_TABLE_ROW* row = FindRow( aNickname );
-        return m.get() != nullptr;
+        wxASSERT( (PLUGIN*) row->plugin );
+
+        return row->plugin->FootprintExists( row->GetFullURI( true ), aFootprintName,
+                                             row->GetProperties() );
     }
     catch( ... )
     {

pcbnew/io_mgr.h

@@ -420,6 +420,13 @@ public:
                                                   const wxString& aFootprintName,
                                                   const PROPERTIES* aProperties = NULL );
 
+    /**
+     * Function FootprintExists
+     * check for the existence of a footprint.
+     */
+    virtual bool FootprintExists( const wxString& aLibraryPath, const wxString& aFootprintName,
+                                  const PROPERTIES* aProperties = NULL );
+
     /**
      * Function FootprintSave
      * will write @a aModule to an existing library located at @a aLibraryPath.

pcbnew/kicad_plugin.cpp

@@ -2103,6 +2103,22 @@ const MODULE* PCB_IO::GetEnumeratedFootprint( const wxString& aLibraryPath,
 }
 
 
+bool PCB_IO::FootprintExists( const wxString& aLibraryPath, const wxString& aFootprintName,
+                              const PROPERTIES* aProperties )
+{
+    // Note: checking the cache sounds like a good idea, but won't catch files which differ
+    // only in case.
+    //
+    // Since this goes out to the native filesystem, we get platform differences (ie: MSW's
+    // case-insensitive filesystem) handled "for free".
+
+    wxFileName footprintFile( aLibraryPath, aFootprintName );
+    footprintFile.SetExt( KiCadFootprintFileExtension );
+
+    return footprintFile.Exists();
+}
+
+
 MODULE* PCB_IO::FootprintLoad( const wxString& aLibraryPath, const wxString& aFootprintName,
                                const PROPERTIES* aProperties )
 {

pcbnew/kicad_plugin.h

@@ -127,6 +127,9 @@ public:
                                           const wxString& aFootprintName,
                                           const PROPERTIES* aProperties = NULL ) override;
 
+    bool FootprintExists( const wxString& aLibraryPath, const wxString& aFootprintName,
+                          const PROPERTIES* aProperties = NULL ) override;
+
     MODULE* FootprintLoad( const wxString& aLibraryPath, const wxString& aFootprintName,
                            const PROPERTIES* aProperties = NULL ) override;
 

pcbnew/plugin.cpp

@@ -81,6 +81,14 @@ const MODULE* PLUGIN::GetEnumeratedFootprint( const wxString& aLibraryPath,
 }
 
 
+bool PLUGIN::FootprintExists( const wxString& aLibraryPath, const wxString& aFootprintName,
+                              const PROPERTIES* aProperties )
+{
+    // default implementation
+    return FootprintLoad( aLibraryPath, aFootprintName, aProperties ) != nullptr;
+}
+
+
 MODULE* PLUGIN::FootprintLoad( const wxString& aLibraryPath, const wxString& aFootprintName,
                                const PROPERTIES* aProperties )
 {