v.gen.c: support `T.typ` - an int for the type index of the generic type `T` (#11175)

cmd/tools/vast/vast.v

@@ -1325,6 +1325,7 @@ fn (t Tree) selector_expr(node ast.SelectorExpr) &Node {
 	obj.add('field_name', t.string_node(node.field_name))
 	obj.add('typ', t.type_node(node.typ))
 	obj.add('name_type', t.type_node(node.name_type))
+	obj.add('gkind_field', t.enum_node(node.gkind_field))
 	obj.add('from_embed_type', t.type_node(node.from_embed_type))
 	obj.add('next_token', t.token_node(node.next_token))
 	obj.add('pos', t.position(node.pos))

vlib/math/math.v

@@ -146,3 +146,43 @@ pub fn radians(degrees f64) f64 {
 pub fn signbit(x f64) bool {
 	return f64_bits(x) & sign_mask != 0
 }
+
+pub fn tolerance(a f64, b f64, tol f64) bool {
+	mut ee := tol
+	// Multiplying by ee here can underflow denormal values to zero.
+	// Check a==b so that at least if a and b are small and identical
+	// we say they match.
+	if a == b {
+		return true
+	}
+	mut d := a - b
+	if d < 0 {
+		d = -d
+	}
+	// note: b is correct (expected) value, a is actual value.
+	// make error tolerance a fraction of b, not a.
+	if b != 0 {
+		ee = ee * b
+		if ee < 0 {
+			ee = -ee
+		}
+	}
+	return d < ee
+}
+
+pub fn close(a f64, b f64) bool {
+	return tolerance(a, b, 1e-14)
+}
+
+pub fn veryclose(a f64, b f64) bool {
+	return tolerance(a, b, 4e-16)
+}
+
+pub fn alike(a f64, b f64) bool {
+	if is_nan(a) && is_nan(b) {
+		return true
+	} else if a == b {
+		return signbit(a) == signbit(b)
+	}
+	return false
+}

vlib/math/math_test.v

@@ -186,50 +186,10 @@ const (
 	]
 )
 
-fn tolerance(a f64, b f64, tol f64) bool {
-	mut ee := tol
-	// Multiplying by ee here can underflow denormal values to zero.
-	// Check a==b so that at least if a and b are small and identical
-	// we say they match.
-	if a == b {
-		return true
-	}
-	mut d := a - b
-	if d < 0 {
-		d = -d
-	}
-	// note: b is correct (expected) value, a is actual value.
-	// make error tolerance a fraction of b, not a.
-	if b != 0 {
-		ee = ee * b
-		if ee < 0 {
-			ee = -ee
-		}
-	}
-	return d < ee
-}
-
-fn close(a f64, b f64) bool {
-	return tolerance(a, b, 1e-14)
-}
-
-fn veryclose(a f64, b f64) bool {
-	return tolerance(a, b, 4e-16)
-}
-
 fn soclose(a f64, b f64, e f64) bool {
 	return tolerance(a, b, e)
 }
 
-fn alike(a f64, b f64) bool {
-	if is_nan(a) && is_nan(b) {
-		return true
-	} else if a == b {
-		return signbit(a) == signbit(b)
-	}
-	return false
-}
-
 fn test_nan() {
 	nan_f64 := nan()
 	assert nan_f64 != nan_f64

vlib/v/ast/ast.v

@@ -129,6 +129,12 @@ pub:
 	pos token.Position
 }
 
+pub enum GenericKindField {
+	unknown
+	name
+	typ
+}
+
 // `foo.bar`
 pub struct SelectorExpr {
 pub:
@@ -142,6 +148,7 @@ pub mut:
 	expr_type       Type // type of `Foo` in `Foo.bar`
 	typ             Type // type of the entire thing (`Foo.bar`)
 	name_type       Type // T in `T.name` or typeof in `typeof(expr).name`
+	gkind_field     GenericKindField // `T.name` => ast.GenericKindField.name, `T.typ` => ast.GenericKindField.typ, or .unknown
 	scope           &Scope
 	from_embed_type Type // holds the type of the embed that the method is called from
 }

vlib/v/checker/checker.v

@@ -3365,12 +3365,23 @@ pub fn (mut c Checker) selector_expr(mut node ast.SelectorExpr) ast.Type {
 		else {}
 	}
 	if name_type > 0 {
-		if node.field_name != 'name' {
-			c.error('invalid field `.$node.field_name` for type `$node.expr`', node.pos)
-		}
 		node.name_type = name_type
+		match node.gkind_field {
+			.name {
 				return ast.string_type
 			}
+			.typ {
+				return ast.int_type
+			}
+			else {
+				if node.field_name != 'name' {
+					c.error('invalid field `.$node.field_name` for type `$node.expr`',
+						node.pos)
+				}
+				return ast.string_type
+			}
+		}
+	}
 
 	old_selector_expr := c.inside_selector_expr
 	c.inside_selector_expr = true

vlib/v/gen/c/cgen.v

@@ -3649,9 +3649,25 @@ fn (mut g Gen) selector_expr(node ast.SelectorExpr) {
 	prevent_sum_type_unwrapping_once := g.prevent_sum_type_unwrapping_once
 	g.prevent_sum_type_unwrapping_once = false
 	if node.name_type > 0 {
+		match node.gkind_field {
+			.name {
 				g.type_name(node.name_type)
 				return
 			}
+			.typ {
+				g.write(int(g.unwrap_generic(node.name_type)).str())
+				return
+			}
+			.unknown {
+				if node.field_name == 'name' {
+					// typeof(expr).name
+					g.type_name(node.name_type)
+					return
+				}
+				g.error('unknown generic field', node.pos)
+			}
+		}
+	}
 	if node.expr_type == 0 {
 		g.checker_bug('unexpected SelectorExpr.expr_type = 0', node.pos)
 	}

vlib/v/parser/parser.v

@@ -2158,6 +2158,11 @@ pub fn (mut p Parser) name_expr() ast.Expr {
 			name := p.check_name()
 			p.check(.dot)
 			field := p.check_name()
+			fkind := match field {
+				'name' { ast.GenericKindField.name }
+				'typ' { ast.GenericKindField.typ }
+				else { ast.GenericKindField.unknown }
+			}
 			pos.extend(p.tok.position())
 			return ast.SelectorExpr{
 				expr: ast.Ident{
@@ -2165,6 +2170,7 @@ pub fn (mut p Parser) name_expr() ast.Expr {
 					scope: p.scope
 				}
 				field_name: field
+				gkind_field: fkind
 				pos: pos
 				scope: p.scope
 			}

vlib/v/tests/generics_T_typ_test.v

@@ -0,0 +1,55 @@
+import math
+
+struct Any {
+mut:
+	data voidptr
+	typ  int
+}
+
+fn make_any<T>(obj T) Any {
+	tsize := int(sizeof(T))
+	mut a := Any{
+		typ: T.typ
+		data: unsafe { malloc(tsize) }
+	}
+	unsafe {
+		vmemcpy(a.data, &obj, tsize)
+	}
+	return a
+}
+
+fn cast<T>(obj Any) ?T {
+	if T.typ == obj.typ {
+		return *&T(obj.data)
+	}
+	return none
+}
+
+fn test_any_values() {
+	arr := [make_any(true), make_any(false), make_any(7), make_any('cat'),
+		make_any([3.1415926535]),
+	]
+	for elm in arr {
+		if b := cast<bool>(elm) {
+			println(!b)
+		} else if i := cast<int>(elm) {
+			println(i + 1)
+		} else if s := cast<string>(elm) {
+			println(s + '!')
+		} else if f := cast<[]f64>(elm) {
+			println(f[0])
+		}
+	}
+	if b := cast<bool>(arr[0]) {
+		assert b == true
+	}
+	if b := cast<bool>(arr[1]) {
+		assert b == false
+	}
+	if s := cast<string>(arr[3]) {
+		assert s == 'cat'
+	}
+	if f := cast<[]f64>(arr[4]) {
+		assert math.veryclose(f[0], 3.1415926535)
+	}
+}