cast const ptr checks:

- Add conversion option AST_CONVOPT_DONTWARNCONST. - Assume we always want to know that constness has changed. - For pointers of different indirection levels, adjust the const mask when comparing
freebasic · Aug 5, 2018 · 03f8a7f · 03f8a7f
1 parent 7185995
commit 03f8a7f
Show file tree

Hide file tree

Showing 3 changed files with 35 additions and 19 deletions.
diff --git a/src/compiler/ast-node-conv.bas b/src/compiler/ast-node-conv.bas
@@ -331,20 +331,16 @@ function astNewCONV _
 					n->cast.doconv = FALSE
 					n->cast.do_convfd2fs = FALSE
 
-					'' Discarding const qualifier bits ?
-					'' TODO: reuse symbCheckConstAssign()?
-					'' TODO: merge with hCheckPtr()?
-
-					n->cast.convconst = true
-
-					if( (options and AST_CONVOPT_DONTCHKPTR) = 0 ) then
-						if( n->cast.convconst ) then
-							if( fbPdCheckIsSet( FB_PDCHECK_CONSTNESS ) ) then
-								errReportWarn( FB_WARNINGMSG_CONSTQUALIFIERDISCARDED )
-							end if
+					'' data types and levels of pointer inderection are the same,
+					'' always record this as const conversion
+					n->cast.convconst = TRUE
+
+					if( (options and AST_CONVOPT_DONTWARNCONST) = 0 ) then
+						if( fbPdCheckIsSet( FB_PDCHECK_CONSTNESS ) ) then
+							'' TODO: return this warning to the caller?
+							errReportWarn( FB_WARNINGMSG_CONSTQUALIFIERDISCARDED )
 						end if
 					end if
-
 				end if
 			else
 				n = l
@@ -490,13 +486,33 @@ function astNewCONV _
 	n->cast.do_convfd2fs = FALSE
 	n->cast.convconst = FALSE
 
-	'' Discarding const qualifier bits ?
+	'' Discarding/changing const qualifier bits ?
 	'' TODO: reuse symbCheckConstAssign()?
 	'' TODO: merge with hCheckPtr()?
+
 	if( typeIsPtr( ldtype ) and typeIsPtr( to_dtype ) ) then
-		n->cast.convconst = ( typeGetConstMask( ldtype ) <> typeGetConstMask( to_dtype ) )
-		if( (options and AST_CONVOPT_DONTCHKPTR) = 0 ) then
-			if( n->cast.convconst ) then
+
+		var cbits = typeGetConstMask( ldtype )
+		var to_cbits = typeGetConstMask( to_dtype )
+
+		'' differing levels of inderection?
+		if( typeGetPtrCnt( ldtype ) <> typeGetPtrCnt( to_dtype ) ) then
+
+			'' increasing? check if we changed/gained any const bits
+			if( typeGetPtrCnt( to_dtype ) > typeGetPtrCnt( ldtype ) ) then
+				cbits shl= (typeGetPtrCnt( to_dtype ) - typeGetPtrCnt( ldtype ))
+
+			'' decreasing. check if we changed/lost any const bits
+			else
+				to_cbits shl= (typeGetPtrCnt( ldtype ) - typeGetPtrCnt( to_dtype ))
+
+			end if
+		end if
+
+		n->cast.convconst = ( cbits <> to_cbits )
+
+		if( n->cast.convconst ) then
+			if( (options and AST_CONVOPT_DONTWARNCONST) = 0 ) then
 				if( fbPdCheckIsSet( FB_PDCHECK_CONSTNESS ) ) then
 					errReportWarn( FB_WARNINGMSG_CONSTQUALIFIERDISCARDED )
 				end if

diff --git a/src/compiler/ast.bi b/src/compiler/ast.bi
@@ -530,6 +530,7 @@ enum AST_CONVOPT
 	AST_CONVOPT_CHECKSTR = &h2
 	AST_CONVOPT_PTRONLY  = &h4
 	AST_CONVOPT_DONTCHKPTR = &h8
+	AST_CONVOPT_DONTWARNCONST = &h10
 end enum
 
 declare function astNewCONV _

diff --git a/src/compiler/rtl-mem.bas b/src/compiler/rtl-mem.bas
@@ -161,10 +161,9 @@ function rtlNullPtrCheck _
    	proc = astNewCALL( PROCLOOKUP( NULLPTRCHK ) )
 
 	'' ptr
-	'' we are CASTing to any ptr, so quiet the ptr checks with AST_CONVOPT_DONTCHKPTR
-	'' astNewCONV => hCheckPtr() will allow any ptr even without this option.
+	'' we are forcing a CAST to any ptr, so quiet the const checks with AST_CONVOPT_DONTWARNCONST
 	if( astNewARG( proc, _
-				   astNewCONV( typeAddrOf( FB_DATATYPE_VOID ), NULL, p, AST_CONVOPT_DONTCHKPTR ), _
+				   astNewCONV( typeAddrOf( FB_DATATYPE_VOID ), NULL, p, AST_CONVOPT_DONTWARNCONST ), _
 				   typeAddrOf( FB_DATATYPE_VOID ) ) = NULL ) then
 		exit function
 	end if