v2: lifetimes; clone() auto-generation for structs with heap-allocated fields (#26859)

Author: medvednikov

cmd/v/v.v

@@ -234,16 +234,19 @@ fn launch_v2_compiler(is_verbose bool, args []string, is_ownership bool) {
 	tool_name := if is_ownership { 'v2_ownership' } else { 'v2' }
 	mut v2_exe := os.getenv(delegated_v2_exe_env)
 	if v2_exe == '' {
-		v2_source := os.join_path(vroot, 'cmd', 'v2', 'v2.v')
+		v2_main_source := os.join_path(vroot, 'cmd', 'v2', 'v2.v')
+		v2_cmd_dir := os.join_path(vroot, 'cmd', 'v2')
+		v2_vlib_dir := os.join_path(vroot, 'vlib', 'v2')
 		v2_exe = cached_v2_executable_path(vroot, is_ownership)
 		v2_exe_dir := os.dir(v2_exe)
 		os.mkdir_all(v2_exe_dir) or {
 			eprintln('cannot create `${v2_exe_dir}`: ${err}')
 			exit(1)
 		}
-		if util.should_recompile_tool(vexe, v2_source, tool_name, v2_exe) {
+		if util.should_recompile_tool(vexe, v2_cmd_dir, tool_name, v2_exe)
+			|| util.should_recompile_tool(vexe, v2_vlib_dir, tool_name, v2_exe) {
 			d_flag := if is_ownership { '-d ownership ' } else { '' }
-			compilation_command := '${os.quoted_path(vexe)} ${d_flag}-o ${os.quoted_path(v2_exe)} ${os.quoted_path(v2_source)}'
+			compilation_command := '${os.quoted_path(vexe)} ${d_flag}-o ${os.quoted_path(v2_exe)} ${os.quoted_path(v2_main_source)}'
 			if is_verbose {
 				println('Compiling ${tool_name} with: "${compilation_command}"')
 			}
@@ -252,7 +255,7 @@ fn launch_v2_compiler(is_verbose bool, args []string, is_ownership bool) {
 			tool_compilation := os.execute(compilation_command)
 			os.chdir(current_work_dir) or {}
 			if tool_compilation.exit_code != 0 {
-				eprintln('cannot compile `${v2_source}`: ${tool_compilation.exit_code}\n${tool_compilation.output}')
+				eprintln('cannot compile `${v2_main_source}`: ${tool_compilation.exit_code}\n${tool_compilation.output}')
 				exit(1)
 			}
 		}

doc/ownership.md

@@ -88,6 +88,26 @@ fn main() {
 }
 ```
 
+### Explicit lifetimes
+
+Ownership mode also supports explicit named lifetimes with `^name`.
+
+Use `&^a T` for a borrowed reference with an explicit lifetime and `[^a]`
+in generic parameter and argument lists:
+
+```v ignore
+struct Ignore {}
+
+struct IgnoreMatch[^a] {}
+
+fn matched_dir_entry[^a](self &^a Ignore) IgnoreMatch[^a] {
+	return IgnoreMatch[^a]{}
+}
+```
+
+`^` is used instead of Rust's `'` because `'` is already used for string and
+character literals in V.
+
 Multiple immutable borrows are allowed:
 
 ```v okfmt

vlib/v/checker/tests/assign_immutable_reference_call_result_err.vv

@@ -11,7 +11,9 @@ fn rere(a &User) &User {
 }
 
 fn main() {
-	ja := User{name: 'foo'}
+	ja := User{
+		name: 'foo'
+	}
 	mut x := rere(ja)
 	x.name = 'bar'
 }

vlib/v/checker/tests/disable_explicit_mutability.vv

@@ -31,5 +31,6 @@ fn main() {
 		}
 		u8 {}
 	}
+
 	println('${counter.value} ${arr.len} ${nums.len} ${inc_copy(1)} ${i}')
 }

vlib/v/checker/tests/fixed_array_new_syntax_size_mismatch_err.vv

@@ -1,3 +1,3 @@
 fn main() {
-	_ := [2]int[1 2 3]
+	_ := [2]int[1, 2, 3]
 }

vlib/v/checker/tests/if_smartcast_mutation_err.vv

@@ -1,4 +1,5 @@
 type SmartcastValue = int | string
+
 fn main() {
 	a := SmartcastValue(1)
 	if a is int {

vlib/v/checker/tests/orm_dynamic_unknown_field_err.vv

@@ -8,7 +8,7 @@ struct User {
 fn main() {
 	db := sqlite.connect(':memory:') or { panic(err) }
 	where_expr := {
-		if true { zzz == 'Alice' },
+		if true { zzz == 'Alice' }
 	}
 	_ := sql db {
 		dynamic select from User where where_expr

vlib/v/checker/tests/pool_processor_callback_array_return_err.vv

@@ -6,7 +6,7 @@ struct Foo {
 
 fn main() {
 	_ := pool.new_pool_processor(
-		callback: fn (mut pp pool.PoolProcessor, idx int, wid int) []Foo {
+		callback: fn (mut pp pool.PoolProcessor, idx int, wid int) []main.Foo {
 			_ = wid
 			return [Foo{
 				page: pp.get_item[int](idx).str()

vlib/v/gen/c/testdata/defer_fn_match_branch_capture.vv

@@ -19,6 +19,7 @@ fn (mut o Object) f(x int) int {
 		}
 		else {}
 	}
+
 	return 42
 }
 

vlib/v2/ast/ast.v

@@ -33,6 +33,7 @@ pub type Expr = ArrayInitExpr
 	| Keyword
 	| KeywordOperator
 	| LambdaExpr
+	| LifetimeExpr
 	| LockExpr
 	| MapInitExpr
 	| MatchExpr
@@ -94,6 +95,7 @@ pub type Type = AnonStructType
 	| NilType
 	| NoneType
 	| OptionType
+	| PointerType
 	| ResultType
 	| ThreadType
 	| TupleType
@@ -155,6 +157,9 @@ pub fn (expr Expr) name() string {
 		Keyword {
 			expr.tok.str()
 		}
+		LifetimeExpr {
+			'^' + expr.name
+		}
 		ModifierExpr {
 			'${expr.kind} ${expr.expr.name()}'
 		}
@@ -239,6 +244,9 @@ pub fn (expr Expr) pos() token.Pos {
 		KeywordOperator {
 			expr.pos
 		}
+		LifetimeExpr {
+			expr.pos
+		}
 		LambdaExpr {
 			expr.pos
 		}
@@ -412,7 +420,7 @@ pub:
 pub struct GenericArgs {
 pub:
 	lhs  Expr
-	args []Expr // concrete types
+	args []Expr // concrete types and lifetimes
 	pos  token.Pos
 }
 
@@ -561,6 +569,12 @@ pub:
 	pos    token.Pos
 }
 
+pub struct LifetimeExpr {
+pub:
+	name string
+	pos  token.Pos
+}
+
 // name_str returns the parameter name.
 pub fn (p Parameter) name_str() string {
 	return p.name
@@ -1039,6 +1053,12 @@ pub:
 	base_type Expr = empty_expr
 }
 
+pub struct PointerType {
+pub:
+	base_type Expr = empty_expr
+	lifetime  string
+}
+
 pub struct ResultType {
 pub:
 	base_type Expr = empty_expr