internal: Split symbStructAddBase() from symbStructBegin()

This could be used to allow adding multiple bases (multiple inheritance,
or at least interfaces...) in the future, by calling symbStructAddBase()
repeatedly.

Author: dkl

src/compiler/ast-node-data.bas

@@ -268,7 +268,7 @@ private sub hCreateDataDesc( )
 	static as FBARRAYDIM dTB(0)
 
 	'' Using FIELD = 1, to pack it as done by the rtlib
-	ast.data.desc = symbStructBegin( NULL, NULL, NULL, "__FB_DATADESC$", NULL, FALSE, 1, NULL, 0, 0 )
+	ast.data.desc = symbStructBegin( NULL, NULL, NULL, "__FB_DATADESC$", NULL, FALSE, 1, FALSE, 0, 0 )
 
 	'' type	as short
 	symbAddField( ast.data.desc, "type", 0, dTB(), _

src/compiler/parser-decl-struct.bas

@@ -631,11 +631,15 @@ private function hTypeAdd _
 
 	dim as FBSYMBOL ptr s = any
 
-	s = symbStructBegin( NULL, NULL, parent, id, id_alias, isunion, align, baseSubtype, 0, 0 )
+	s = symbStructBegin( NULL, NULL, parent, id, id_alias, isunion, align, (baseSubtype <> NULL), 0, 0 )
 	if( s = NULL ) then
 		errReportEx( FB_ERRMSG_DUPDEFINITION, id )
 		'' error recovery: create a fake symbol
-		s = symbStructBegin( NULL, NULL, parent, symbUniqueLabel( ), NULL, isunion, align, NULL, 0, 0 )
+		s = symbStructBegin( NULL, NULL, parent, symbUniqueLabel( ), NULL, isunion, align, (baseSubtype <> NULL), 0, 0 )
+	end if
+
+	if( baseSubtype ) then
+		symbStructAddBase( s, baseSubtype )
 	end if
 
 	'' Comment? SttSeparator

src/compiler/symb-comp.bas

@@ -1315,7 +1315,7 @@ sub symbCompRTTIInit( )
 	'' type fb_RTTI$
 	'' (using fb_RTTI$ instead of $fb_RTTI to prevent gdb/stabs confusion,
 	'' where leading $ has special meaning)
-	rttitype = symbStructBegin( NULL, NULL, NULL, "fb_RTTI$", "fb_RTTI$", FALSE, 0, NULL, 0, 0 )
+	rttitype = symbStructBegin( NULL, NULL, NULL, "fb_RTTI$", "fb_RTTI$", FALSE, 0, FALSE, 0, 0 )
 	symb.rtti.fb_rtti = rttitype
 
 	'' stdlibvtable as any ptr
@@ -1338,7 +1338,7 @@ sub symbCompRTTIInit( )
 		ptypename = @"OBJECT"
 	end if
 	'' (using fb_Object$ instead of $fb_Object - ditto)
-	objtype = symbStructBegin( NULL, NULL, NULL, ptypename, "fb_Object$", FALSE, 0, NULL, 0, 0 )
+	objtype = symbStructBegin( NULL, NULL, NULL, ptypename, "fb_Object$", FALSE, 0, FALSE, 0, 0 )
 	symb.rtti.fb_object = objtype
 	symbSetHasRTTI( objtype )
 	symbSetIsUnique( objtype )

src/compiler/symb-struct.bas

@@ -24,7 +24,7 @@ function symbStructBegin _
 		byval id_alias as const zstring ptr, _
 		byval isunion as integer, _
 		byval align as integer, _
-		byval base_ as FBSYMBOL ptr, _
+		byval is_derived as integer, _
 		byval attrib as integer, _
 		byval options as integer _
 	) as FBSYMBOL ptr
@@ -84,35 +84,38 @@ function symbStructBegin _
 	s->udt.retdtype = FB_DATATYPE_INVALID
 	s->udt.dbg.typenum = INVALID
 	s->udt.ext = NULL
+	s->udt.base = NULL
 
-	'' extending another UDT?
-	if( base_ <> NULL ) then
-		static as FBARRAYDIM dTB(0 to 0)
-
-		'' (using base$ instead of $base to prevent gdb/stabs confusion,
-		'' where leading $ has special meaning)
-		s->udt.base = symbAddField( s, "base$", 0, dTB(), FB_DATATYPE_STRUCT, base_, 0, 0, 0 )
-
+	if( is_derived ) then
 		symbSetIsUnique( s )
 		symbNestBegin( s, FALSE )
-		symbNamespaceImportEx( base_, s )
-
-		if( symbGetHasRTTI( base_ ) ) then
-			symbSetHasRTTI( s )
-
-			'' inherit the vtable elements and abstracts counts
-			assert( base_->udt.ext->vtableelements >= 2 )
-			symbUdtAllocExt( s )
-			s->udt.ext->vtableelements = base_->udt.ext->vtableelements
-			s->udt.ext->abstractcount = base_->udt.ext->abstractcount
-		end if
-	else
-		s->udt.base = NULL
 	end if
 
 	function = s
 end function
 
+sub symbStructAddBase( byval s as FBSYMBOL ptr, byval base_ as FBSYMBOL ptr )
+	static as FBARRAYDIM dTB(0 to 0)
+
+	assert( s->udt.base = NULL )
+
+	'' (using base$ instead of $base to prevent gdb/stabs confusion,
+	'' where leading $ has special meaning)
+	s->udt.base = symbAddField( s, "base$", 0, dTB(), FB_DATATYPE_STRUCT, base_, 0, 0, 0 )
+
+	symbNamespaceImportEx( base_, s )
+
+	if( symbGetHasRTTI( base_ ) ) then
+		symbSetHasRTTI( s )
+
+		'' inherit the vtable elements and abstracts counts
+		assert( base_->udt.ext->vtableelements >= 2 )
+		symbUdtAllocExt( s )
+		s->udt.ext->vtableelements = base_->udt.ext->vtableelements
+		s->udt.ext->abstractcount = base_->udt.ext->abstractcount
+	end if
+end sub
+
 function typeCalcNaturalAlign _
 	( _
 		byval dtype as integer, _

src/compiler/symb-var.bas

@@ -19,7 +19,7 @@ sub symbVarInit( )
 	static as FBARRAYDIM dTB(0)
 
 	'' type FBARRAYDIM
-	symb.fbarraydim = symbStructBegin( NULL, NULL, NULL, "__FB_ARRAYDIMTB$", NULL, FALSE, 0, NULL, 0, 0 )
+	symb.fbarraydim = symbStructBegin( NULL, NULL, NULL, "__FB_ARRAYDIMTB$", NULL, FALSE, 0, FALSE, 0, 0 )
 
 	'' elements		as integer
 	symbAddField( symb.fbarraydim, "elements", 0, dTB(), _
@@ -187,7 +187,7 @@ function symbAddArrayDescriptorType _
 	'' descriptor type, e.g. in hMangleUdtId().
 	''
 	attrib or= FB_SYMBATTRIB_DESCRIPTOR
-	sym = symbStructBegin( symtb, hashtb, NULL, id, aliasid, FALSE, 0, NULL, attrib, FB_SYMBOPT_PRESERVECASE )
+	sym = symbStructBegin( symtb, hashtb, NULL, id, aliasid, FALSE, 0, FALSE, attrib, FB_SYMBOPT_PRESERVECASE )
 	assert( sym )
 	dTB(0).lower = 0
 	dTB(0).upper = 0

src/compiler/symb.bi

@@ -1168,11 +1168,13 @@ declare function symbStructBegin _
 		byval id_alias as const zstring ptr, _
 		byval isunion as integer, _
 		byval align as integer, _
-		byval base_ as FBSYMBOL ptr, _
+		byval is_derived as integer, _
 		byval attrib as integer, _
 		byval options as integer _
 	) as FBSYMBOL ptr
 
+declare sub symbStructAddBase( byval struct as FBSYMBOL ptr, byval base_ as FBSYMBOL ptr )
+
 declare function typeCalcNaturalAlign _
 	( _
 		byval dtype as integer, _