Initial commit: Go 1.23 release state

test/switch.go

@@ -0,0 +1,417 @@
+// run
+
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Test switch statements.
+
+package main
+
+import "os"
+
+func assert(cond bool, msg string) {
+	if !cond {
+		print("assertion fail: ", msg, "\n")
+		panic(1)
+	}
+}
+
+func main() {
+	i5 := 5
+	i7 := 7
+	hello := "hello"
+
+	switch true {
+	case i5 < 5:
+		assert(false, "<")
+	case i5 == 5:
+		assert(true, "!")
+	case i5 > 5:
+		assert(false, ">")
+	}
+
+	switch {
+	case i5 < 5:
+		assert(false, "<")
+	case i5 == 5:
+		assert(true, "!")
+	case i5 > 5:
+		assert(false, ">")
+	}
+
+	switch x := 5; true {
+	case i5 < x:
+		assert(false, "<")
+	case i5 == x:
+		assert(true, "!")
+	case i5 > x:
+		assert(false, ">")
+	}
+
+	switch x := 5; true {
+	case i5 < x:
+		assert(false, "<")
+	case i5 == x:
+		assert(true, "!")
+	case i5 > x:
+		assert(false, ">")
+	}
+
+	switch i5 {
+	case 0:
+		assert(false, "0")
+	case 1:
+		assert(false, "1")
+	case 2:
+		assert(false, "2")
+	case 3:
+		assert(false, "3")
+	case 4:
+		assert(false, "4")
+	case 5:
+		assert(true, "5")
+	case 6:
+		assert(false, "6")
+	case 7:
+		assert(false, "7")
+	case 8:
+		assert(false, "8")
+	case 9:
+		assert(false, "9")
+	default:
+		assert(false, "default")
+	}
+
+	switch i5 {
+	case 0, 1, 2, 3, 4:
+		assert(false, "4")
+	case 5:
+		assert(true, "5")
+	case 6, 7, 8, 9:
+		assert(false, "9")
+	default:
+		assert(false, "default")
+	}
+
+	switch i5 {
+	case 0:
+	case 1:
+	case 2:
+	case 3:
+	case 4:
+		assert(false, "4")
+	case 5:
+		assert(true, "5")
+	case 6:
+	case 7:
+	case 8:
+	case 9:
+	default:
+		assert(i5 == 5, "good")
+	}
+
+	switch i5 {
+	case 0:
+		dummy := 0
+		_ = dummy
+		fallthrough
+	case 1:
+		dummy := 0
+		_ = dummy
+		fallthrough
+	case 2:
+		dummy := 0
+		_ = dummy
+		fallthrough
+	case 3:
+		dummy := 0
+		_ = dummy
+		fallthrough
+	case 4:
+		dummy := 0
+		_ = dummy
+		assert(false, "4")
+	case 5:
+		dummy := 0
+		_ = dummy
+		fallthrough
+	case 6:
+		dummy := 0
+		_ = dummy
+		fallthrough
+	case 7:
+		dummy := 0
+		_ = dummy
+		fallthrough
+	case 8:
+		dummy := 0
+		_ = dummy
+		fallthrough
+	case 9:
+		dummy := 0
+		_ = dummy
+		fallthrough
+	default:
+		dummy := 0
+		_ = dummy
+		assert(i5 == 5, "good")
+	}
+
+	fired := false
+	switch i5 {
+	case 0:
+		dummy := 0
+		_ = dummy
+		fallthrough // tests scoping of cases
+	case 1:
+		dummy := 0
+		_ = dummy
+		fallthrough
+	case 2:
+		dummy := 0
+		_ = dummy
+		fallthrough
+	case 3:
+		dummy := 0
+		_ = dummy
+		fallthrough
+	case 4:
+		dummy := 0
+		_ = dummy
+		assert(false, "4")
+	case 5:
+		dummy := 0
+		_ = dummy
+		fallthrough
+	case 6:
+		dummy := 0
+		_ = dummy
+		fallthrough
+	case 7:
+		dummy := 0
+		_ = dummy
+		fallthrough
+	case 8:
+		dummy := 0
+		_ = dummy
+		fallthrough
+	case 9:
+		dummy := 0
+		_ = dummy
+		fallthrough
+	default:
+		dummy := 0
+		_ = dummy
+		fired = !fired
+		assert(i5 == 5, "good")
+	}
+	assert(fired, "fired")
+
+	count := 0
+	switch i5 {
+	case 0:
+		count = count + 1
+		fallthrough
+	case 1:
+		count = count + 1
+		fallthrough
+	case 2:
+		count = count + 1
+		fallthrough
+	case 3:
+		count = count + 1
+		fallthrough
+	case 4:
+		count = count + 1
+		assert(false, "4")
+	case 5:
+		count = count + 1
+		fallthrough
+	case 6:
+		count = count + 1
+		fallthrough
+	case 7:
+		count = count + 1
+		fallthrough
+	case 8:
+		count = count + 1
+		fallthrough
+	case 9:
+		count = count + 1
+		fallthrough
+	default:
+		assert(i5 == count, "good")
+	}
+	assert(fired, "fired")
+
+	switch hello {
+	case "wowie":
+		assert(false, "wowie")
+	case "hello":
+		assert(true, "hello")
+	case "jumpn":
+		assert(false, "jumpn")
+	default:
+		assert(false, "default")
+	}
+
+	fired = false
+	switch i := i5 + 2; i {
+	case i7:
+		fired = true
+	default:
+		assert(false, "fail")
+	}
+	assert(fired, "var")
+
+	// switch on nil-only comparison types
+	switch f := func() {}; f {
+	case nil:
+		assert(false, "f should not be nil")
+	default:
+	}
+
+	switch m := make(map[int]int); m {
+	case nil:
+		assert(false, "m should not be nil")
+	default:
+	}
+
+	switch a := make([]int, 1); a {
+	case nil:
+		assert(false, "m should not be nil")
+	default:
+	}
+
+	// switch on interface.
+	switch i := interface{}("hello"); i {
+	case 42:
+		assert(false, `i should be "hello"`)
+	case "hello":
+		assert(true, "hello")
+	default:
+		assert(false, `i should be "hello"`)
+	}
+
+	// switch on implicit bool converted to interface
+	// was broken: see issue 3980
+	switch i := interface{}(true); {
+	case i:
+		assert(true, "true")
+	case false:
+		assert(false, "i should be true")
+	default:
+		assert(false, "i should be true")
+	}
+
+	// switch on interface with constant cases differing by type.
+	// was rejected by compiler: see issue 4781
+	type T int
+	type B bool
+	type F float64
+	type S string
+	switch i := interface{}(float64(1.0)); i {
+	case nil:
+		assert(false, "i should be float64(1.0)")
+	case (*int)(nil):
+		assert(false, "i should be float64(1.0)")
+	case 1:
+		assert(false, "i should be float64(1.0)")
+	case T(1):
+		assert(false, "i should be float64(1.0)")
+	case F(1.0):
+		assert(false, "i should be float64(1.0)")
+	case 1.0:
+		assert(true, "true")
+	case "hello":
+		assert(false, "i should be float64(1.0)")
+	case S("hello"):
+		assert(false, "i should be float64(1.0)")
+	case true, B(false):
+		assert(false, "i should be float64(1.0)")
+	case false, B(true):
+		assert(false, "i should be float64(1.0)")
+	}
+
+	// switch on array.
+	switch ar := [3]int{1, 2, 3}; ar {
+	case [3]int{1, 2, 3}:
+		assert(true, "[1 2 3]")
+	case [3]int{4, 5, 6}:
+		assert(false, "ar should be [1 2 3]")
+	default:
+		assert(false, "ar should be [1 2 3]")
+	}
+
+	// switch on channel
+	switch c1, c2 := make(chan int), make(chan int); c1 {
+	case nil:
+		assert(false, "c1 did not match itself")
+	case c2:
+		assert(false, "c1 did not match itself")
+	case c1:
+		assert(true, "chan")
+	default:
+		assert(false, "c1 did not match itself")
+	}
+
+	// empty switch
+	switch {
+	}
+
+	// empty switch with default case.
+	fired = false
+	switch {
+	default:
+		fired = true
+	}
+	assert(fired, "fail")
+
+	// Default and fallthrough.
+	count = 0
+	switch {
+	default:
+		count++
+		fallthrough
+	case false:
+		count++
+	}
+	assert(count == 2, "fail")
+
+	// fallthrough to default, which is not at end.
+	count = 0
+	switch i5 {
+	case 5:
+		count++
+		fallthrough
+	default:
+		count++
+	case 6:
+		count++
+	}
+	assert(count == 2, "fail")
+
+	i := 0
+	switch x := 5; {
+	case i < x:
+		os.Exit(0)
+	case i == x:
+	case i > x:
+		os.Exit(1)
+	}
+
+	// Unified IR converts the tag and all case values to empty
+	// interface, when any of the case values aren't assignable to the
+	// tag value's type. Make sure that `case nil:` compares against the
+	// tag type's nil value (i.e., `(*int)(nil)`), not nil interface
+	// (i.e., `any(nil)`).
+	switch (*int)(nil) {
+	case nil:
+		// ok
+	case any(nil):
+		assert(false, "case any(nil) matched")
+	default:
+		assert(false, "default matched")
+	}
+}