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Russ Cox 46f138f288 cmd/compile, go/types: fix checking of bad type switch
Consider the following program:

	package p

	func f() {
		x := 1
		v := 2
		switch v.(type) {
		case int:
			println(x)
			println(x / 0)
		case 1:
		}
	}

Before this CL, the compiler prints:

	x.go:4:2: x declared but not used
	x.go:6:9: v (variable of type int) is not an interface

x is in fact used, and other errors in the switch go undiagnosed.

This commit fixes that problem by processing the switch statement
even when the 'not an interface' error is reported.

Now the compiler drops the spurious 'declared but not used'
and adds two previously undiagnosed problems:

	x.go:6:9: v (variable of type int) is not an interface
	x.go:9:15: invalid operation: division by zero
	x.go:10:7: 1 is not a type

go/types was printing roughly the same thing the compiler did before,
and now still prints roughly the same thing the compiler does after.
(The only differences are in the exact reported columns.)

Fixes #50493.

Change-Id: I317883f29077b1b4bbd0e8793617fd3bb31aa0f8
Reviewed-on: https://go-review.googlesource.com/c/go/+/379117
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
2022-01-18 19:03:00 +00:00
.github .github: remove duplicate security link 2022-01-07 17:55:09 +00:00
api api: promote next to go1.18 2021-12-14 17:43:51 +00:00
doc doc: mention that GOAMD64 is a compile-time setting 2022-01-13 00:53:53 +00:00
lib/time lib/time, time/tzdata: update to 2021e 2021-11-11 05:16:39 +00:00
misc src/runtime: mark asanread and asanwrite functions as NOSPLIT 2022-01-05 09:50:29 +00:00
src cmd/compile, go/types: fix checking of bad type switch 2022-01-18 19:03:00 +00:00
test cmd/compile: support field access for typeparam with structural constraint 2022-01-18 18:16:14 +00:00
.gitattributes all: treat all files as binary, but check in .bat with CRLF 2020-06-08 15:31:43 +00:00
.gitignore internal/buildcfg: move build configuration out of cmd/internal/objabi 2021-04-16 19:20:53 +00:00
AUTHORS A+C: add Bharath Kumar Uppala (individual CLA) 2021-11-29 00:57:09 +00:00
CONTRIBUTING.md all: restore changes from faulty merge/revert 2018-02-12 20:13:59 +00:00
CONTRIBUTORS A+C: add Bharath Kumar Uppala (individual CLA) 2021-11-29 00:57:09 +00:00
LICENSE
PATENTS
README.md README.md: update contribute URL 2021-09-30 13:33:21 +00:00
SECURITY.md SECURITY.md: update go versions 2019-09-26 15:34:57 +00:00
codereview.cfg codereview.cfg: add codereview.cfg for master branch 2021-02-19 18:44:53 +00:00

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