#!stacks
"gopanic" && "go/types.(*operand).setConst:+14" && "go/types.(*Checker).basicLit:+20"

Issue created by stacks.

A BasicLit.Kind other than INT, FLOAT, IMAG, CHAR, STRING cannot result from the parser, and there are no assignments in x/tools that update the Kind field. Every place in x/tools that constructs a BasicLit fills in the Kind field to one of these values (except in gopls/internal/golang/undeclared.go, but that AST is only fed to format.Node). So this means the AST has become corrupted.

This stack -JV2Tg was reported by telemetry:

• crash/crash
• runtime.gopanic:+69,+0x167
• go/types.(*Checker).handleBailout:+25,+0x96
• go/types.(*Checker).Files.deferwrap1:+0,+0x24
• runtime.gopanic:+50,+0x131
• go/types.(*operand).setConst:+14,+0x184
• go/types.(*Checker).basicLit:+20,+0x84
• go/types.(*Checker).exprInternal:+19,+0x19e
• go/types.(*Checker).rawExpr:+10,+0x18b
• go/types.(*Checker).expr:+1,+0x2f
• go/types.(*Checker).binary:+4,+0xcb
• go/types.(*Checker).exprInternal:+134,+0x8e4
• go/types.(*Checker).rawExpr:+10,+0x18b
• go/types.(*Checker).expr:+1,+0x2f
• go/types.(*Checker).stmt:+200,+0x10ce
• go/types.(*Checker).stmtList:+9,+0x84
• go/types.(*Checker).stmt:+192,+0x56d

golang.org/x/tools/gopls@v0.21.0 go1.25.5 windows/amd64 gopls.client=other,vscode (1)

Use this command to reproduce the executable:
(HOME=$(mktemp -d); GOOS=windows GOARCH=amd64 GOTOOLCHAIN=go1.25.5 go install golang.org/x/tools/gopls@v0.21.0 && find $HOME/go/bin -type f)
To disassemble: go tool objdump exe | less