From 83f651c29a877312bfa3a1f285e63ca841cea923 Mon Sep 17 00:00:00 2001
From: joe-conigliaro <joe@vlang.io>
Date: Sun, 6 Dec 2020 02:36:27 +1100
Subject: [PATCH] cgen: autofree - know where to stop freeing parent scops on
 continue/break

---
 vlib/v/ast/ast.v                             |  7 ++++---
 vlib/v/gen/cgen.v                            | 19 ++++++++++++-------
 vlib/v/parser/for.v                          |  1 +
 vlib/v/parser/parser.v                       |  2 ++
 vlib/v/tests/valgrind/1.strings_and_arrays.v | 20 +++++++++++++++-----
 5 files changed, 34 insertions(+), 15 deletions(-)

diff --git a/vlib/v/ast/ast.v b/vlib/v/ast/ast.v
index e1acd34b01..f3f81f25ea 100644
--- a/vlib/v/ast/ast.v
+++ b/vlib/v/ast/ast.v
@@ -286,9 +286,10 @@ pub mut:
 // break, continue
 pub struct BranchStmt {
 pub:
-	kind  token.Kind
-	label string
-	pos   token.Position
+	kind       token.Kind
+	label      string
+	pos        token.Position
+	parent_pos int
 }
 
 pub struct CallExpr {
diff --git a/vlib/v/gen/cgen.v b/vlib/v/gen/cgen.v
index 3650204d44..c872b82e26 100644
--- a/vlib/v/gen/cgen.v
+++ b/vlib/v/gen/cgen.v
@@ -858,7 +858,8 @@ fn (mut g Gen) stmt(node ast.Stmt) {
 				// continue or break
 				if g.pref.autofree && !g.is_builtin_mod {
 					g.writeln('// free before continue/break')
-					g.autofree_scope_vars(node.pos.pos - 1, node.pos.line_nr, false)
+					g.autofree_scope_vars_stop(node.pos.pos - 1, node.pos.line_nr, true,
+						node.parent_pos)
 				}
 				g.writeln('$node.kind;')
 			}
@@ -2061,8 +2062,11 @@ fn (mut g Gen) gen_clone_assignment(val ast.Expr, right_sym table.TypeSymbol, ad
 	return true
 }
 
-// fn (mut g Gen) autofree_scope_vars(pos int, line_nr int) {
 fn (mut g Gen) autofree_scope_vars(pos int, line_nr int, free_parent_scopes bool) {
+	g.autofree_scope_vars_stop(pos, line_nr, free_parent_scopes, -1)
+}
+
+fn (mut g Gen) autofree_scope_vars_stop(pos int, line_nr int, free_parent_scopes bool, stop_pos int) {
 	if g.is_builtin_mod {
 		// In `builtin` everything is freed manually.
 		return
@@ -2078,12 +2082,12 @@ fn (mut g Gen) autofree_scope_vars(pos int, line_nr int, free_parent_scopes bool
 		return
 	}
 	g.writeln('// autofree_scope_vars(pos=$pos line_nr=$line_nr scope.pos=$scope.start_pos scope.end_pos=$scope.end_pos)')
-	// g.autofree_scope_vars2(scope, scope.end_pos)
-	g.autofree_scope_vars2(scope, scope.start_pos, scope.end_pos, line_nr, free_parent_scopes)
+	g.autofree_scope_vars2(scope, scope.start_pos, scope.end_pos, line_nr, free_parent_scopes,
+		stop_pos)
 }
 
 // fn (mut g Gen) autofree_scope_vars2(scope &ast.Scope, end_pos int) {
-fn (mut g Gen) autofree_scope_vars2(scope &ast.Scope, start_pos int, end_pos int, line_nr int, free_parent_scopes bool) {
+fn (mut g Gen) autofree_scope_vars2(scope &ast.Scope, start_pos int, end_pos int, line_nr int, free_parent_scopes bool, stop_pos int) {
 	if isnil(scope) {
 		return
 	}
@@ -2129,9 +2133,10 @@ fn (mut g Gen) autofree_scope_vars2(scope &ast.Scope, start_pos int, end_pos int
 	// }
 	// ```
 	// if !isnil(scope.parent) && line_nr > 0 {
-	if free_parent_scopes && !isnil(scope.parent) {
+	if free_parent_scopes && !isnil(scope.parent) &&
+		(stop_pos == -1 || scope.parent.start_pos >= stop_pos) {
 		g.writeln('// af parent scope:')
-		g.autofree_scope_vars2(scope.parent, start_pos, end_pos, line_nr, true)
+		g.autofree_scope_vars2(scope.parent, start_pos, end_pos, line_nr, true, stop_pos)
 	}
 }
 
diff --git a/vlib/v/parser/for.v b/vlib/v/parser/for.v
index 924faf5925..6b70ac40e6 100644
--- a/vlib/v/parser/for.v
+++ b/vlib/v/parser/for.v
@@ -9,6 +9,7 @@ import v.table
 fn (mut p Parser) for_stmt() ast.Stmt {
 	p.check(.key_for)
 	pos := p.tok.position()
+	p.branch_parent_pos = pos.pos
 	p.open_scope()
 	p.inside_for = true
 	if p.tok.kind == .key_match {
diff --git a/vlib/v/parser/parser.v b/vlib/v/parser/parser.v
index b89e0b3455..d33f41672e 100644
--- a/vlib/v/parser/parser.v
+++ b/vlib/v/parser/parser.v
@@ -60,6 +60,7 @@ mut:
 	vet_errors        []string
 	cur_fn_name       string
 	in_generic_params bool // indicates if parsing between `<` and `>` of a method/function
+	branch_parent_pos int  // used in BranchStmt (continue/break) autofree stop position
 }
 
 // for tests
@@ -690,6 +691,7 @@ pub fn (mut p Parser) stmt(is_top_level bool) ast.Stmt {
 				kind: tok.kind
 				label: label
 				pos: tok.position()
+				parent_pos: p.branch_parent_pos
 			}
 		}
 		.key_unsafe {
diff --git a/vlib/v/tests/valgrind/1.strings_and_arrays.v b/vlib/v/tests/valgrind/1.strings_and_arrays.v
index 1981bd79ca..32f83224b7 100644
--- a/vlib/v/tests/valgrind/1.strings_and_arrays.v
+++ b/vlib/v/tests/valgrind/1.strings_and_arrays.v
@@ -258,17 +258,28 @@ fn free_before_break() {
 		q := [1, 2, 3]
 		break
 	}
-	/*
 	for {
-		qq := [1, 2, 3]
+		aa := [1, 2, 3]
 		if true {
 			// breaking should free only vars in the closest for loop's scope
 			// `qq`, not `s`
 			break
 		}
+		// nested 1
+		for {
+			bb := [4, 5, 6]
+			if true {
+				break
+			}
+			// nested 2
+			for {
+				cc := [7, 8, 9]
+				if true {
+					break
+				}
+			}
+		}
 	}
-	*/
-	/*
 	mut i := 0
 	for {
 		i++
@@ -280,7 +291,6 @@ fn free_before_break() {
 			continue
 		}
 	}
-	*/
 }
 
 struct User {