x/tools/gopls/internal/analysis/modernize: crash in minmax

[adonovan]

I got this crash today while running modernize, but don't have time to investigate at this moment:

xtools$ modernize -diff ./internal/...
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x2 addr=0x20 pc=0x104be0014]

goroutine 964 [running]:
golang.org/x/tools/internal/typeparams.CoreType({0x0?, 0x0?})
	/Users/adonovan/w/xtools/internal/typeparams/coretype.go:16 +0x24
golang.org/x/tools/gopls/internal/analysis/modernize.maybeNaN({0x0?, 0x0?})
	/Users/adonovan/w/xtools/gopls/internal/analysis/modernize/minmax.go:234 +0x24
golang.org/x/tools/gopls/internal/analysis/modernize.minmax.minmax.filesUsing.func2.minmax.minmax.filesUsing.func2.Cursor.Children.func3.minmax.minmax.filesUsing.func2-range3.minmax-range1-range4({0x14002defa88?, 0x4c56e18?})
	/Users/adonovan/w/xtools/gopls/internal/analysis/modernize/minmax.go:190 +0x114
golang.org/x/tools/internal/astutil/cursor.Cursor.Preorder.func1(0x140086bd3e0)
	/Users/adonovan/w/xtools/internal/astutil/cursor/cursor.go:129 +0xbc
golang.org/x/tools/gopls/internal/analysis/modernize.minmax-range1(...)
	/Users/adonovan/w/xtools/gopls/internal/analysis/modernize/minmax.go:184
golang.org/x/tools/gopls/internal/analysis/modernize.minmax.minmax.filesUsing.func2-range3(...)
	/Users/adonovan/w/xtools/gopls/internal/analysis/modernize/modernize.go:136
golang.org/x/tools/gopls/internal/analysis/modernize.minmax.minmax.filesUsing.func2.Cursor.Children.func3(...)
	/Users/adonovan/w/xtools/internal/astutil/cursor/cursor.go:422
golang.org/x/tools/gopls/internal/analysis/modernize.minmax.filesUsing.func2(...)
	/Users/adonovan/w/xtools/gopls/internal/analysis/modernize/modernize.go:134
golang.org/x/tools/gopls/internal/analysis/modernize.minmax(0x1400837f420)
	/Users/adonovan/w/xtools/gopls/internal/analysis/modernize/minmax.go:182 +0x268
golang.org/x/tools/gopls/internal/analysis/modernize.run(0x1400837f420)
	/Users/adonovan/w/xtools/gopls/internal/analysis/modernize/modernize.go:87 +0x150
golang.org/x/tools/go/analysis/checker.(*Action).execOnce.func3(...)
	/Users/adonovan/w/xtools/go/analysis/checker/checker.go:367
golang.org/x/tools/go/analysis/checker.(*Action).execOnce(0x140041b8f20)
	/Users/adonovan/w/xtools/go/analysis/checker/checker.go:388 +0x898
sync.(*Once).doSlow(0x0?, 0x0?)
	/Users/adonovan/w/goroot/src/sync/once.go:78 +0xe8
sync.(*Once).Do(...)
	/Users/adonovan/w/goroot/src/sync/once.go:69
golang.org/x/tools/go/analysis/checker.(*Action).exec(...)
	/Users/adonovan/w/xtools/go/analysis/checker/checker.go:265
golang.org/x/tools/go/analysis/checker.execAll.func1(0x0?)
	/Users/adonovan/w/xtools/go/analysis/checker/checker.go:253 +0x4c
created by golang.org/x/tools/go/analysis/checker.execAll in goroutine 1
	/Users/adonovan/w/xtools/go/analysis/checker/checker.go:259 +0x140
xtools$ 

[gabyhelp]

Related Issues

• x/tools/internal/analysisinternal: panic in IsTypeNamed #71456 (closed)
• x/tools/internal/refactor/inline: nil deref in (*freeVisitor).declare #73321
• x/tools/gopls/internal/analysis/modernize: Panic in modernize/sortslice.go #71786 (closed)
• x/tools/gopls: Highlight: nil deref panic on CompositeLiteral with no type #68918 (closed)
• x/tools/gopls: panic in analyzer due to type checker errors #32413 (closed)
• x/tools/gopls: panic in analysis #60551 (closed)
• x/tools/gopls: invalid memory address or nil pointer dereference on highlight #68927 (closed)
• x/tools/gopls: crash in testFuncs with *error argument #70927 (closed)
• x/tools/cmd/gopls: nil pointer dereference when creating new file #34366 (closed)
• x/tools/gopls: automated issue report (crash) #40449 (closed)

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}

[xieyuschen]

I recalled this has been fixed in https://go-review.googlesource.com/c/tools/+/662195, and we have guard the input of CoreType won't be nil. Did you try the tip of gopls @adonovan ?

[adonovan]

I had used go install ./local/path/to/main.go at tip, but apparently that doesn't actually install anything. Using go build -o exe did the right thing, and the bug does appear to be fixed. Sorry for the false alarm.