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cmd/compile: miscompilation of value switch involving generic interface types #53477

mdempsky opened this issue Jun 21, 2022 · 2 comments
NeedsFix release-blocker


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@mdempsky mdempsky commented Jun 21, 2022

The above program should terminate quietly with success. However, in Go 1.18, it instead silently miscompiles into code that at runtime panics:

panic: interface conversion: main.X is not interface { M(go.shape.int_0) }: missing method M

Since this is a silent miscompilation, I think a fix and backport are appropriate. Ideally fix it to compile correctly, but even changing it to ICE would be preferable IMO.

/cc @randall77 @dr2chase @cuonglm

@mdempsky mdempsky added the NeedsFix label Jun 21, 2022
@mdempsky mdempsky added this to the Go1.19 milestone Jun 21, 2022
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@gopherbot gopherbot commented Jun 21, 2022

Change mentions this issue: test: add regress test for #53477

gopherbot pushed a commit that referenced this issue Jun 21, 2022
This test already passes for GOEXPERIMENT=unified; add regress test to
ensure it stays that way.

Updates #53477.

Change-Id: Ib7aa7428260595077052207899edcc044a6ab1c8
Run-TryBot: Matthew Dempsky <>
Auto-Submit: Matthew Dempsky <>
Reviewed-by: David Chase <>
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@gopherbot gopherbot commented Jun 24, 2022

Change mentions this issue: [dev.unified] all: merge master (5a1c5b8) into dev.unified

gopherbot pushed a commit that referenced this issue Jun 24, 2022

- test/run.go

  Textual conflict adding to the known failures list for the nounified

Merge List:

+ 2022-06-24 5a1c5b8 cmd/go: add per-package indexing for modules outside mod cache
+ 2022-06-24 b9c4d94 cmd/go/internal/list: update help info with Deprecated field
+ 2022-06-24 73475ef go/types, types2: print qualified object names in cycle errors
+ 2022-06-24 3e58ef6 go/types, types2: better errors for == when type sets are empty
+ 2022-06-24 d38f1d1 doc/go1.19: Linux race detector now requires glibc 2.17
+ 2022-06-23 de5329f debug/dwarf: handle malformed line table with bad program offset
+ 2022-06-23 15605ca embed: document additional file name restrictions
+ 2022-06-22 2e773a3 test: add test that causes gofrontend crash
+ 2022-06-22 ff17b7d cmd/compile: don't use dictionary convert to shaped empty interface
+ 2022-06-22 2a3b467 cmd/go: make module .zip files group/world readable
+ 2022-06-22 bdab4cf cmd/go, cmd/link: support failure to create _cgo_import.go
+ 2022-06-22 aca37d1 cmd/go: avoid indexing modules in GOROOT
+ 2022-06-22 111cdb5 all: update to current revision
+ 2022-06-22 4045b1b cmd/compile: fix assert condition in generic method call
+ 2022-06-22 6bad7e8 compress/gzip: always close bodyReader in Example_compressingReader
+ 2022-06-22 606c6c3 encoding/xml: check nil pointer in DecodeElement
+ 2022-06-22 f571518 cmd/cgo: dont override declared struct type
+ 2022-06-22 92c9b81 net: don't set netGo = true on Windows with no cgo
+ 2022-06-22 be0b2a3 cmd/trace: add basic documentation to main page
+ 2022-06-22 b004c73 go/types, types2: fix parameter order dependence in type inference
+ 2022-06-21 f2c7e78 spec: document operations which accept []byte|string constrained types
+ 2022-06-21 ab422f2 runtime/trace: ignore fallback stacks in test
+ 2022-06-21 66685fb doc/go1.19: use correct link to sync/atomic docs
+ 2022-06-21 4b236b4 runtime: convert flaky semaphore linearity test into benchmark
+ 2022-06-21 530511b cmd/go/internal/modindex: avoid walking modules when not needed
+ 2022-06-21 c2d373d cmd/compile: allow 128-bit values to be spilled
+ 2022-06-21 19ed442 test: add regress test for #53477
+ 2022-06-20 3fcbfb0 doc/go1.19: fix HTML validation issues
+ 2022-06-18 527ace0 cmd/compile: skip substituting closures in unsafe builtins arguments
+ 2022-06-17 ec58e3f test: add regress test for #53419
+ 2022-06-17 103cc66 cmd/go/internal/modfetch: prevent duplicate hashes in go.sum
+ 2022-06-17 d42a488 sync: add more notes about Cond behavior
+ 2022-06-17 9e2f289 cmd/go/internal/work: log clearer detail for subprocess errors in (*Builder).toolID
+ 2022-06-17 dd2d00f net: fix flaky *TimeoutMustNotReturn tests
+ 2022-06-17 6c25ba6 go/token: delete unused File.set field
+ 2022-06-16 9068c68 cmd/dist: add package . to 'go test' commands
+ 2022-06-16 7bad615 runtime: write much more direct test for semaphore waiter scalability
+ 2022-06-16 f38a580 cmd/go: add more tracing

Change-Id: I912c5879165e03f4d7f8ac3ee9241d50fc92a419
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