all: comptime_call - simplify tmpl scoping, solves many issues.

vlib/v/checker/checker.v

@@ -124,6 +124,7 @@ mut:
 	inside_println_arg               bool
 	inside_decl_rhs                  bool
 	inside_if_guard                  bool // true inside the guard condition of `if x := opt() {}`
+	vweb_comptime_call_pos           int  // needed for correctly checking use before decl for vweb templates
 }
 
 pub fn new_checker(table &ast.Table, pref &pref.Preferences) &Checker {
@@ -3104,9 +3105,15 @@ pub fn (mut c Checker) ident(mut node ast.Ident) ast.Type {
 					return obj.typ
 				}
 				ast.Var {
-					// incase var was not marked as used yet (vweb tmpl)
-					// obj.is_used = true
-					if node.pos.pos < obj.pos.pos {
+					// inside vweb tmpl ident positions are meaningless, use the position of the comptime call.
+					// if the variable is declared before the comptime call then we can assume all is well.
+					// `node.name !in node.scope.objects` checks it's an inherited var (not defined in the tmpl).
+					node_pos := if c.pref.is_vweb && node.name !in node.scope.objects {
+						c.vweb_comptime_call_pos
+					} else {
+						node.pos.pos
+					}
+					if node_pos < obj.pos.pos {
 						c.error('undefined variable `$node.name` (used before declaration)',
 							node.pos)
 					}

vlib/v/checker/comptime.v

@@ -36,28 +36,8 @@ fn (mut c Checker) comptime_call(mut node ast.ComptimeCall) ast.Type {
 			is_vweb: true
 		}
 		mut c2 := new_checker(c.table, pref2)
+		c2.vweb_comptime_call_pos = node.pos.pos
 		c2.check(node.vweb_tmpl)
-		mut caller_scope := c.fn_scope.innermost(node.pos.pos)
-		mut i := 0 // tmp counter var for skipping first three tmpl vars
-		for k, _ in c2.file.scope.children[0].objects {
-			if i < 2 {
-				// Skip first three because they are tmpl vars see vlib/vweb/tmpl/tmpl.v
-				i++
-				continue
-			}
-			tmpl_obj := unsafe { c2.file.scope.children[0].objects[k] }
-			if tmpl_obj is ast.Var {
-				if mut caller_var := caller_scope.find_var(tmpl_obj.name) {
-					// var is used in the tmpl so mark it as used in the caller
-					caller_var.is_used = true
-					// update props from the caller scope var to the tmpl scope var
-					c2.file.scope.children[0].objects[k] = ast.Var{
-						...(*caller_var)
-						pos: tmpl_obj.pos
-					}
-				}
-			}
-		}
 		c.warnings << c2.warnings
 		c.errors << c2.errors
 		c.notices << c2.notices

vlib/v/gen/c/cgen.v

@@ -3697,10 +3697,8 @@ fn (mut g Gen) ident(node ast.Ident) {
 			g.write('${name}.val')
 			return
 		}
-		// TODO: investigate why node.obj is pointing to outdated ScopeObject?
-		// v := node.obj
-		// if v is ast.Var {
-		if v := node.scope.find_var(node.name) {
+		v := node.obj
+		if v is ast.Var {
 			is_auto_heap = v.is_auto_heap && (!g.is_assign_lhs || g.assign_op != .decl_assign)
 			if is_auto_heap {
 				g.write('(*(')

vlib/v/parser/comptime.v

@@ -245,10 +245,6 @@ fn (mut p Parser) comptime_call() ast.ComptimeCall {
 			println('$path:${i + 1}: $line')
 		}
 	}
-	mut scope := &ast.Scope{
-		start_pos: 0
-		parent: p.table.global_scope
-	}
 	$if trace_comptime ? {
 		println('')
 		println('>>> template for $path:')
@@ -256,25 +252,11 @@ fn (mut p Parser) comptime_call() ast.ComptimeCall {
 		println('>>> end of template END')
 		println('')
 	}
-	mut file := parse_comptime(v_code, p.table, p.pref, scope)
+	// the tmpl inherits all parent scopes. previous functionality was just to
+	// inherit the scope from which the comptime call was made and no parents.
+	// this is much simpler and allws access to globals. can be changed if needed.
+	mut file := parse_comptime(tmpl_path, v_code, p.table, p.pref, p.scope)
 	file.path = tmpl_path
-	// copy vars from current fn scope into vweb_tmpl scope
-	for mut stmt in file.stmts {
-		if mut stmt is ast.FnDecl {
-			if stmt.name == 'main.vweb_tmpl_$tmp_fn_name' {
-				for _, mut obj in p.scope.objects {
-					if mut obj is ast.Var {
-						stmt.scope.register(ast.Var{
-							...obj
-							is_used: true
-							pos: stmt.body_pos
-						})
-					}
-				}
-				break
-			}
-		}
-	}
 	return ast.ComptimeCall{
 		scope: 0
 		is_vweb: true

vlib/v/parser/parser.v

@@ -115,11 +115,12 @@ pub fn parse_stmt(text string, table &ast.Table, scope &ast.Scope) ast.Stmt {
 	return p.stmt(false)
 }
 
-pub fn parse_comptime(text string, table &ast.Table, pref &pref.Preferences, scope &ast.Scope) &ast.File {
+pub fn parse_comptime(tmpl_path string, text string, table &ast.Table, pref &pref.Preferences, scope &ast.Scope) &ast.File {
 	$if trace_parse_comptime ? {
 		eprintln('> ${@MOD}.${@FN} text: $text')
 	}
 	mut p := Parser{
+		file_name: tmpl_path
 		scanner: scanner.new_scanner(text, .skip_comments, pref)
 		table: table
 		pref: pref

vlib/v/tests/comptime_call_tmpl_variable_scope_test.tpl

@@ -0,0 +1,2 @@
+$a.name
+$b

vlib/v/tests/comptime_call_tmpl_variable_scope_test.v

@@ -0,0 +1,11 @@
+[heap]
+struct MyHeapStruct {
+	name string
+}
+
+// make sure dereferencing of heap stucts works in selector expr (in tmpl), 
+fn test_heap_struct_dereferencing_in_selector_expr() {
+	a := MyHeapStruct{name: 'my_heap_struct_a'}
+	b := 2
+	$tmpl('comptime_call_tmpl_variable_scope_test.tpl')
+}