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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-16 19:23:18 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-16 19:23:18 +0000 |
commit | 43a123c1ae6613b3efeed291fa552ecd909d3acf (patch) | |
tree | fd92518b7024bc74031f78a1cf9e454b65e73665 /test/typeparam/issue50002.go | |
parent | Initial commit. (diff) | |
download | golang-1.20-43a123c1ae6613b3efeed291fa552ecd909d3acf.tar.xz golang-1.20-43a123c1ae6613b3efeed291fa552ecd909d3acf.zip |
Adding upstream version 1.20.14.upstream/1.20.14upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | test/typeparam/issue50002.go | 64 |
1 files changed, 64 insertions, 0 deletions
diff --git a/test/typeparam/issue50002.go b/test/typeparam/issue50002.go new file mode 100644 index 0000000..42d97f5 --- /dev/null +++ b/test/typeparam/issue50002.go @@ -0,0 +1,64 @@ +// run + +// Copyright 2021 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 for cases where certain instantiations of a generic function (F in this +// example) will always fail on a type assertion or mismatch on a type case. + +package main + +import "fmt" + +type S struct{} + +func (S) M() byte { + return 0 +} + +type I[T any] interface { + M() T +} + +func F[T, A any](x I[T], shouldMatch bool) { + switch x.(type) { + case A: + if !shouldMatch { + fmt.Printf("wanted mis-match, got match") + } + default: + if shouldMatch { + fmt.Printf("wanted match, got mismatch") + } + } + + _, ok := x.(A) + if ok != shouldMatch { + fmt.Printf("ok: got %v, wanted %v", ok, shouldMatch) + } + + if !shouldMatch { + defer func() { + if shouldMatch { + fmt.Printf("Shouldn't have panicked") + } + recover() + }() + } + _ = x.(A) + if !shouldMatch { + fmt.Printf("Should have panicked") + } +} + +func main() { + // Test instantiation where the type switch/type asserts can't possibly succeed + // (since string does not implement I[byte]). + F[byte, string](S{}, false) + + // Test instantiation where the type switch/type asserts should succeed + // (since S does implement I[byte]) + F[byte, S](S{}, true) + F[byte, S](I[byte](S{}), true) +} |