checker: support value array elements of `[heap]` type inside struct ref (#9899)

vlib/v/checker/checker.v

@@ -86,6 +86,7 @@ mut:
 	using_new_err_struct bool
 	inside_selector_expr bool
 	inside_println_arg   bool
+	inside_decl_rhs      bool
 }
 
 pub fn new_checker(table &ast.Table, pref &pref.Preferences) Checker {
@@ -515,7 +516,8 @@ pub fn (mut c Checker) struct_init(mut struct_init ast.StructInit) ast.Type {
 			c.error('struct `$type_sym.name` is declared with a `[noinit]` attribute, so ' +
 				'it cannot be initialized with `$type_sym.name{}`', struct_init.pos)
 		}
-		if info.is_heap && !c.inside_ref_lit && !c.inside_unsafe && !struct_init.typ.is_ptr() {
+		if info.is_heap && c.inside_decl_rhs && !c.inside_ref_lit && !c.inside_unsafe
+			&& !struct_init.typ.is_ptr() {
 			c.error('`$type_sym.name` type can only be used as a reference `&$type_sym.name` or inside a `struct` reference',
 				struct_init.pos)
 		}
@@ -2979,7 +2981,9 @@ pub fn (mut c Checker) assign_stmt(mut assign_stmt ast.AssignStmt) {
 					c.inside_ref_lit = c.inside_ref_lit || left.info.share == .shared_t
 				}
 			}
+			c.inside_decl_rhs = is_decl
 			right_type := c.expr(assign_stmt.right[i])
+			c.inside_decl_rhs = false
 			c.inside_ref_lit = old_inside_ref_lit
 			if assign_stmt.right_types.len == i {
 				assign_stmt.right_types << c.check_expr_opt_call(assign_stmt.right[i],
@@ -5895,7 +5899,9 @@ pub fn (mut c Checker) mark_as_referenced(mut node ast.Expr) {
 			}
 		}
 		ast.SelectorExpr {
-			c.mark_as_referenced(mut &node.expr)
+			if !node.expr_type.is_ptr() {
+				c.mark_as_referenced(mut &node.expr)
+			}
 		}
 		ast.IndexExpr {
 			c.mark_as_referenced(mut &node.left)

vlib/v/tests/heap_reference_test.v

@@ -0,0 +1,101 @@
+[heap]
+struct GitStructure {
+pub mut:
+	root  string
+	repos []&GitRepo
+}
+
+[heap]
+struct GitRepo {
+	id int [skip]
+pub:
+	path string // path on filesystem
+	name string
+}
+
+pub fn (mut gitstructure GitStructure) repo_get(name string) ?&GitRepo {
+	for r in gitstructure.repos {
+		if r.name == name {
+			if name != '' {
+				r2 := gitstructure.repos[r.id]
+				return r2
+			}
+		}
+	}
+	return error("Could not find repo for account name: '$name'")
+}
+
+fn test_opt_ref_return() {
+	mut gitstruct := &GitStructure{
+		root: 'r'
+		repos: [
+			&GitRepo{
+				id: 0
+				path: 'testpath'
+				name: 'thename'
+			},
+		]
+	}
+	mut err_msg := ''
+	a := gitstruct.repo_get('thename') or {
+		err_msg = '$err'
+		r := &GitRepo{}
+		r
+	}
+	assert a.path == 'testpath'
+	assert err_msg == ''
+	b := gitstruct.repo_get('wrong_name') or {
+		err_msg = '$err'
+		r := &GitRepo{}
+		r
+	}
+	assert b.path == ''
+	assert err_msg == "Could not find repo for account name: 'wrong_name'"
+}
+
+[heap]
+struct GitStructureNoRef {
+pub mut:
+	root  string
+	repos []GitRepo
+}
+
+pub fn (mut gitstructure GitStructureNoRef) repo_get(name string) ?&GitRepo {
+	for r in gitstructure.repos {
+		if r.name == name {
+			if name != '' {
+				r2 := &gitstructure.repos[r.id]
+				return r2
+			}
+		}
+	}
+	return error("Could not find repo for account name: '$name'")
+}
+
+fn test_opt_return() {
+	mut gitstruct := &GitStructureNoRef{
+		root: 'r'
+		repos: [
+			GitRepo{
+				id: 0
+				path: 'testpath2'
+				name: 'thename2'
+			},
+		]
+	}
+	mut err_msg := ''
+	a := gitstruct.repo_get('thename2') or {
+		err_msg = '$err'
+		r := &GitRepo{}
+		r
+	}
+	assert a.path == 'testpath2'
+	assert err_msg == ''
+	b := gitstruct.repo_get('wrong_name2') or {
+		err_msg = '$err'
+		r := &GitRepo{}
+		r
+	}
+	assert b.path == ''
+	assert err_msg == "Could not find repo for account name: 'wrong_name2'"
+}

vlib/v/tests/ref_struct_test.v

@@ -63,3 +63,34 @@ fn test_ref_field() {
 	}
 	assert y.a.n == 29
 }
+
+// Yxc should become [heap] implicitly because `Abc` is
+
+struct Yxc {
+mut:
+	a []Abc
+}
+
+fn mod_heap_array(mut x Yxc) {
+	x.a << Abc{
+		n: 9
+	}
+	x.a[1] = Abc{
+		n: 13
+	}
+}
+
+fn test_heap_array() {
+	mut z := &Yxc{
+		a: [
+			Abc{
+				n: 4
+			},
+			Abc{
+				n: 7
+			},
+		]
+	}
+	mod_heap_array(mut z)
+	assert z.a[1].n == 13
+}