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go/test/switch5.go
Daniel Martí 495f55d27d cmd/compile: make duplicate expr cases readable
Instead of just printing the value, print the original node to make the
error more human-friendly. Also print the value if its string form is
different than the original node, to make sure it's obvious what value
was duplicated.

This means that "case '@', '@':", which used to print:

	duplicate case 64 in switch

Will now print:

	duplicate case '@' (value 64) in switch

Factor this logic out into its own function to reuse it in range cases
and any other place where we might want to print a node and its value in
the future.

Also needed to split the errorcheck files because expression switch case
duplicates are now detected earlier, so they stop the compiler before it
gets to generating the AST and detecting the type switch case
duplicates.

Fixes #20112.

Change-Id: I9009b50dec0d0e705e5de9c9ccb08f1dce8a5a99
Reviewed-on: https://go-review.googlesource.com/41852
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2017-05-19 18:11:51 +00:00

95 lines
2.2 KiB
Go

// errorcheck
// Copyright 2016 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.
// Verify that switch statements with duplicate cases are detected by the compiler.
// Does not compile.
package main
func f0(x int) {
switch x {
case 0:
case 0: // ERROR "duplicate case 0 in switch"
}
switch x {
case 0:
case int(0): // ERROR "duplicate case int.0. .value 0. in switch"
}
}
func f1(x float32) {
switch x {
case 5:
case 5: // ERROR "duplicate case 5 in switch"
case 5.0: // ERROR "duplicate case 5 in switch"
}
}
func f2(s string) {
switch s {
case "":
case "": // ERROR "duplicate case .. in switch"
case "abc":
case "abc": // ERROR "duplicate case .abc. in switch"
}
}
func f3(e interface{}) {
switch e {
case 0:
case 0: // ERROR "duplicate case 0 in switch"
case int64(0):
case float32(10):
case float32(10): // ERROR "duplicate case float32\(10\) .value 10. in switch"
case float64(10):
case float64(10): // ERROR "duplicate case float64\(10\) .value 10. in switch"
}
}
func f5(a [1]int) {
switch a {
case [1]int{0}:
case [1]int{0}: // OK -- see issue 15896
}
}
// Ensure duplicate const bool clauses are accepted.
func f6() int {
switch {
case 0 == 0:
return 0
case 1 == 1: // Intentionally OK, even though a duplicate of the above const true
return 1
}
return 2
}
// Ensure duplicates in ranges are detected (issue #17517).
func f7(a int) {
switch a {
case 0:
case 0, 1: // ERROR "duplicate case 0"
case 1, 2, 3, 4: // ERROR "duplicate case 1"
}
}
// Ensure duplicates with simple literals are printed as they were
// written, not just their values. Particularly useful for runes.
func f8(r rune) {
const x = 10
switch r {
case 33, 33: // ERROR "duplicate case 33 in switch"
case 34, '"': // ERROR "duplicate case '"' .value 34. in switch"
case 35, rune('#'): // ERROR "duplicate case rune.'#'. .value 35. in switch"
case 36, rune(36): // ERROR "duplicate case rune.36. .value 36. in switch"
case 37, '$'+1: // ERROR "duplicate case '\$' \+ 1 .value 37. in switch"
case 'b':
case 'a', 'b', 'c', 'd': // ERROR "duplicate case 'b' .value 98."
case x, x: // ERROR "duplicate case x .value 10."
}
}