all: new function `isreftype(T)` to know if `T` contains pointers (#10438)

cmd/tools/vast/vast.v

@@ -979,6 +979,9 @@ fn (t Tree) expr(expr ast.Expr) &Node {
 		ast.SizeOf {
 			return t.size_of(expr)
 		}
+		ast.IsRefType {
+			return t.is_ref_type(expr)
+		}
 		ast.PrefixExpr {
 			return t.prefix_expr(expr)
 		}
@@ -1225,6 +1228,16 @@ fn (t Tree) size_of(node ast.SizeOf) &Node {
 	return obj
 }
 
+fn (t Tree) is_ref_type(node ast.IsRefType) &Node {
+	mut obj := new_object()
+	obj.add('ast_type', t.string_node('IsRefType'))
+	obj.add('is_type', t.bool_node(node.is_type))
+	obj.add('typ', t.type_node(node.typ))
+	obj.add('expr', t.expr(node.expr))
+	obj.add('pos', t.position(node.pos))
+	return obj
+}
+
 fn (t Tree) prefix_expr(node ast.PrefixExpr) &Node {
 	mut obj := new_object()
 	obj.add('ast_type', t.string_node('PrefixExpr'))

vlib/v/ast/ast.v

@@ -12,10 +12,10 @@ pub type TypeDecl = AliasTypeDecl | FnTypeDecl | SumTypeDecl
 pub type Expr = AnonFn | ArrayDecompose | ArrayInit | AsCast | Assoc | AtExpr | BoolLiteral |
 	CTempVar | CallExpr | CastExpr | ChanInit | CharLiteral | Comment | ComptimeCall |
 	ComptimeSelector | ConcatExpr | DumpExpr | EmptyExpr | EnumVal | FloatLiteral | GoExpr |
-	Ident | IfExpr | IfGuardExpr | IndexExpr | InfixExpr | IntegerLiteral | Likely | LockExpr |
-	MapInit | MatchExpr | NodeError | None | OffsetOf | OrExpr | ParExpr | PostfixExpr |
-	PrefixExpr | RangeExpr | SelectExpr | SelectorExpr | SizeOf | SqlExpr | StringInterLiteral |
-	StringLiteral | StructInit | TypeNode | TypeOf | UnsafeExpr
+	Ident | IfExpr | IfGuardExpr | IndexExpr | InfixExpr | IntegerLiteral | IsRefType |
+	Likely | LockExpr | MapInit | MatchExpr | NodeError | None | OffsetOf | OrExpr | ParExpr |
+	PostfixExpr | PrefixExpr | RangeExpr | SelectExpr | SelectorExpr | SizeOf | SqlExpr |
+	StringInterLiteral | StringLiteral | StructInit | TypeNode | TypeOf | UnsafeExpr
 
 pub type Stmt = AsmStmt | AssertStmt | AssignStmt | Block | BranchStmt | CompFor | ConstDecl |
 	DeferStmt | EmptyStmt | EnumDecl | ExprStmt | FnDecl | ForCStmt | ForInStmt | ForStmt |
@@ -1338,6 +1338,15 @@ pub mut:
 	typ Type
 }
 
+pub struct IsRefType {
+pub:
+	is_type bool
+	expr    Expr // checker uses this to set typ
+	pos     token.Position
+pub mut:
+	typ Type
+}
+
 pub struct OffsetOf {
 pub:
 	struct_type Type
@@ -1516,10 +1525,10 @@ pub fn (expr Expr) position() token.Position {
 		}
 		NodeError, ArrayDecompose, ArrayInit, AsCast, Assoc, AtExpr, BoolLiteral, CallExpr,
 		CastExpr, ChanInit, CharLiteral, ConcatExpr, Comment, ComptimeCall, ComptimeSelector,
-		EnumVal, DumpExpr, FloatLiteral, GoExpr, Ident, IfExpr, IntegerLiteral, Likely, LockExpr,
-		MapInit, MatchExpr, None, OffsetOf, OrExpr, ParExpr, PostfixExpr, PrefixExpr, RangeExpr,
-		SelectExpr, SelectorExpr, SizeOf, SqlExpr, StringInterLiteral, StringLiteral, StructInit,
-		TypeNode, TypeOf, UnsafeExpr {
+		EnumVal, DumpExpr, FloatLiteral, GoExpr, Ident, IfExpr, IntegerLiteral, IsRefType, Likely,
+		LockExpr, MapInit, MatchExpr, None, OffsetOf, OrExpr, ParExpr, PostfixExpr, PrefixExpr,
+		RangeExpr, SelectExpr, SelectorExpr, SizeOf, SqlExpr, StringInterLiteral, StringLiteral,
+		StructInit, TypeNode, TypeOf, UnsafeExpr {
 			return expr.pos
 		}
 		IndexExpr {

vlib/v/checker/checker.v

@@ -4833,6 +4833,12 @@ pub fn (mut c Checker) expr(node ast.Expr) ast.Type {
 			}
 			return ast.u32_type
 		}
+		ast.IsRefType {
+			if !node.is_type {
+				node.typ = c.expr(node.expr)
+			}
+			return ast.bool_type
+		}
 		ast.OffsetOf {
 			return c.offset_of(node)
 		}

vlib/v/fmt/fmt.v

@@ -601,6 +601,9 @@ pub fn (mut f Fmt) expr(node ast.Expr) {
 		ast.SizeOf {
 			f.size_of(node)
 		}
+		ast.IsRefType {
+			f.is_ref_type(node)
+		}
 		ast.SqlExpr {
 			f.sql_expr(node)
 		}
@@ -2321,6 +2324,16 @@ pub fn (mut f Fmt) size_of(node ast.SizeOf) {
 	f.write(')')
 }
 
+pub fn (mut f Fmt) is_ref_type(node ast.IsRefType) {
+	f.write('isreftype(')
+	if node.is_type {
+		f.write(f.table.type_to_str_using_aliases(node.typ, f.mod2alias))
+	} else {
+		f.expr(node.expr)
+	}
+	f.write(')')
+}
+
 pub fn (mut f Fmt) sql_expr(node ast.SqlExpr) {
 	// sql app.db { select from Contributor where repo == id && user == 0 }
 	f.write('sql ')

vlib/v/gen/c/cgen.v

@@ -3303,6 +3303,15 @@ fn (mut g Gen) expr(node ast.Expr) {
 			styp := g.typ(node_typ)
 			g.write('/*SizeOf*/ sizeof(${util.no_dots(styp)})')
 		}
+		ast.IsRefType {
+			node_typ := g.unwrap_generic(node.typ)
+			sym := g.table.get_type_symbol(node_typ)
+			if sym.language == .v && sym.kind in [.placeholder, .any] {
+				g.error('unknown type `$sym.name`', node.pos)
+			}
+			is_ref_type := g.contains_ptr(node_typ)
+			g.write('/*IsRefType*/ $is_ref_type')
+		}
 		ast.OffsetOf {
 			styp := g.typ(node.struct_type)
 			g.write('/*OffsetOf*/ (u32)(__offsetof(${util.no_dots(styp)}, $node.field))')

vlib/v/gen/js/js.v

@@ -637,7 +637,7 @@ fn (mut g JsGen) expr(node ast.Expr) {
 		ast.SelectorExpr {
 			g.gen_selector_expr(node)
 		}
-		ast.SizeOf {
+		ast.SizeOf, ast.IsRefType {
 			// TODO
 		}
 		ast.OffsetOf {

vlib/v/markused/walker.v

@@ -298,7 +298,7 @@ fn (mut w Walker) expr(node ast.Expr) {
 				w.expr(node.high)
 			}
 		}
-		ast.SizeOf {
+		ast.SizeOf, ast.IsRefType {
 			w.expr(node.expr)
 		}
 		ast.StringInterLiteral {

vlib/v/parser/pratt.v

@@ -190,7 +190,8 @@ pub fn (mut p Parser) check_expr(precedence int) ?ast.Expr {
 				pos: pos
 			}
 		}
-		.key_sizeof {
+		.key_sizeof, .key_isreftype {
+			is_reftype := p.tok.kind == .key_isreftype
 			p.next() // sizeof
 			p.check(.lpar)
 			pos := p.tok.position()
@@ -198,10 +199,18 @@ pub fn (mut p Parser) check_expr(precedence int) ?ast.Expr {
 			// assume mod. prefix leads to a type
 			if is_known_var || !(p.known_import(p.tok.lit) || p.tok.kind.is_start_of_type()) {
 				expr := p.expr(0)
-				node = ast.SizeOf{
-					is_type: false
-					expr: expr
-					pos: pos
+				if is_reftype {
+					node = ast.IsRefType{
+						is_type: false
+						expr: expr
+						pos: pos
+					}
+				} else {
+					node = ast.SizeOf{
+						is_type: false
+						expr: expr
+						pos: pos
+					}
 				}
 			} else {
 				if p.tok.kind == .name {
@@ -209,12 +218,20 @@ pub fn (mut p Parser) check_expr(precedence int) ?ast.Expr {
 				}
 				save_expr_mod := p.expr_mod
 				p.expr_mod = ''
-				sizeof_type := p.parse_type()
+				arg_type := p.parse_type()
 				p.expr_mod = save_expr_mod
-				node = ast.SizeOf{
-					is_type: true
-					typ: sizeof_type
-					pos: pos
+				if is_reftype {
+					node = ast.IsRefType{
+						is_type: true
+						typ: arg_type
+						pos: pos
+					}
+				} else {
+					node = ast.SizeOf{
+						is_type: true
+						typ: arg_type
+						pos: pos
+					}
 				}
 			}
 			p.check(.rpar)

vlib/v/tests/isreftype_test.v

@@ -0,0 +1,58 @@
+struct S1 {
+	p voidptr
+}
+
+struct S2 {
+	i int
+}
+
+struct S3 {
+	x &S2
+	y int
+}
+
+struct S4 {
+	x S2
+mut:
+	y f64
+}
+
+struct S5 {
+	S3
+	a f32
+}
+
+fn test_isreftype() {
+	assert isreftype(S1) == true
+	assert isreftype(S2) == false
+	assert isreftype(S3) == true
+	assert isreftype(S4) == false
+	assert isreftype(S5) == true
+	assert isreftype(f64) == false
+	assert isreftype([]f64) == true
+	assert isreftype([3]int) == false
+}
+
+fn check_ref<T>() string {
+	if isreftype(T) {
+		return 'ref'
+	} else {
+		return 'no ref'
+	}
+}
+
+fn test_generic_ref() {
+	assert check_ref<f64>() == 'no ref'
+	assert check_ref<S3>() == 'ref'
+}
+
+fn test_expression_ref() {
+	mut a := S3{
+		x: &S2{}
+	}
+	b := S4{}
+	c := 32.5 * 6
+	assert isreftype(a) == true
+	assert isreftype(b) == false
+	assert isreftype(c) == false
+}

vlib/v/token/token.v

@@ -111,6 +111,7 @@ pub enum Kind {
 	key_return
 	key_select
 	key_sizeof
+	key_isreftype
 	key_likely
 	key_unlikely
 	key_offsetof
@@ -267,6 +268,7 @@ fn build_token_str() []string {
 	s[Kind.key_return] = 'return'
 	s[Kind.key_module] = 'module'
 	s[Kind.key_sizeof] = 'sizeof'
+	s[Kind.key_isreftype] = 'isreftype'
 	s[Kind.key_likely] = '_likely_'
 	s[Kind.key_unlikely] = '_unlikely_'
 	s[Kind.key_go] = 'go'