reflect: Value.Seq iteration value types not matching the type of given int types

[rothelius]

Go version

go version go1.24.0 darwin/amd64

Output of go env in your module/workspace:

AR='ar'
CC='clang'
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_ENABLED='1'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
CXX='clang++'
GCCGO='gccgo'
GO111MODULE='on'
GOAMD64='v1'
GOARCH='amd64'
GOAUTH='netrc'
GOBIN=''
GOCACHE='/Users/fabianr/Library/Caches/go-build'
GOCACHEPROG=''
GODEBUG=''
GOENV='/Users/fabianr/Library/Application Support/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFIPS140='off'
GOFLAGS=''
GOGCCFLAGS='-fPIC -arch x86_64 -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -ffile-prefix-map=/var/folders/5y/2cd0ydxn7nl7sz2nnk3d91xc0000gn/T/go-build15690302=/tmp/go-build -gno-record-gcc-switches -fno-common'
GOHOSTARCH='amd64'
GOHOSTOS='darwin'
GOINSECURE=''
GOMOD='/Users/fabianr/seq/go.mod'
GOMODCACHE='/Users/fabianr/e/be/gamelogic/gohome/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='darwin'
GOPATH='/Users/fabianr/e/be/gamelogic/gohome'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/usr/local/go'
GOSUMDB='sum.golang.org'
GOTELEMETRY='local'
GOTELEMETRYDIR='/Users/fabianr/Library/Application Support/go/telemetry'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/usr/local/go/pkg/tool/darwin_amd64'
GOVCS=''
GOVERSION='go1.24.0'
GOWORK=''
PKG_CONFIG='pkg-config'

What did you do?

Ranged over the result of calling Seq on the reflect value of a named integer type.

What did you see happen?

The reflect.Values produced by the iteration having the type of the given value's underlying type.

What did you expect to see?

From the Go 1.23 release notes:

The new methods Value.Seq and Value.Seq2 return sequences that iterate over the value as though it were used in a for/range loop.

Thus, I expected the produced Values to be of the same type as the given integer, as for range behaves:
Playground example

[gabyhelp]

Related Issues

• reflect: Value.Seq panicking on functional iterator methods #71874 (closed)
• Slice element types are 'masked' when reflect.Value.Index is called on slices of interfaces #39096 (closed)
• reflect does not convert method to type #25571 (closed)
• reflect: reflect.Value.IsZero results false positive #34108 (closed)
• Struct Reflection result is wrong #41667 (closed)
• reflect: support array pointer in Value.Len() #52411 (closed)
• reflect: Index(X).Type() returning slice element type instead of actual type #65306 (closed)
• reflect: MakeMap() and not native map type wrong behavior #37716 (closed)
• reflect: artifact in Type.String() for nested generic local type #67395 (closed)
• reflect: not equal comments for NumMethod() in Value and Type. #20848 (closed)

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[qiulaidongfeng]

Thanks report.
I will fix.

[gopherbot]

Change https://go.dev/cl/651855 mentions this issue: reflect: let Value.Seq return the iteration value correct type

[ianlancetaylor]

@gopherbot Please open backport issues.

The reflect package is using the wrong types when iterating over a sequence of user-defined types.

[gopherbot]

Backport issue(s) opened: #71915 (for 1.23), #71916 (for 1.24).

Remember to create the cherry-pick CL(s) as soon as the patch is submitted to master, according to https://go.dev/wiki/MinorReleases.