Panic "Cannot add pos to new symbol" when multiple struct fields share an anonymous struct as their type (concise syntax)

[qaisjp]

Summary

A dependency of ours is crashing when we run scip-go:

panic: Cannot add pos to new symbol: symbol:"scip-go gomod github.com/rivo/tview 0d02bb78244d `github.com/rivo/tview`/TextArea#cursor.row."  documentation:"```go\nstruct field row int\n```" symbol:"scip-go gomod github.com/rivo/tview 0d02bb78244d `github.com/rivo/tview`/TextArea#cursor.selectionStart.row."  documentation:"```go\nstruct field row int\n```"

Full log output of time scip-go:

➜ time scip-go
scip-go
Resolving module name
  Go standard library version:  go1.18
  Resolved module name       :  github.com/rivo/tview

Configuration:
  Skip Implementations: false
  Skip Test           : false
Loading Packages
Visiting Packages
panic: Cannot add pos to new symbol: symbol:"scip-go gomod github.com/rivo/tview 0d02bb78244d `github.com/rivo/tview`/TextArea#cursor.row."  documentation:"```go\nstruct field row int\n```" symbol:"scip-go gomod github.com/rivo/tview 0d02bb78244d `github.com/rivo/tview`/TextArea#cursor.selectionStart.row."  documentation:"```go\nstruct field row int\n```"

goroutine 1793 [running]:
github.com/sourcegraph/scip-go/internal/lookup.(*Package).Set(0x1400ad46320, 0x9dcd19, 0x1400ea19400)
	/Users/qaisjp/go/pkg/mod/github.com/sourcegraph/scip-go@v0.1.12/internal/lookup/lookup.go:51 +0xf8
github.com/sourcegraph/scip-go/internal/document.(*Document).SetNewSymbolForPos(0x1400e9dd110, {0x1400ea00780, 0x6c}, {0x0?, 0x0?}, 0x1401530f6e0?, 0x9dcd19)
	/Users/qaisjp/go/pkg/mod/github.com/sourcegraph/scip-go@v0.1.12/internal/document/document.go:103 +0x378
github.com/sourcegraph/scip-go/internal/document.(*Document).SetNewSymbol(...)
	/Users/qaisjp/go/pkg/mod/github.com/sourcegraph/scip-go@v0.1.12/internal/document/document.go:69
github.com/sourcegraph/scip-go/internal/visitors.typeVisitor.Visit({0x1400e9dd110, 0x140004eb980, 0x1400ea02330, 0x14015311880, 0x0}, {0x10094ec90, 0x140153113c0})
	/Users/qaisjp/go/pkg/mod/github.com/sourcegraph/scip-go@v0.1.12/internal/visitors/visitor_type.go:117 +0x764
go/ast.Walk({0x10094c400?, 0x1400ea05e30?}, {0x10094ec90, 0x140153113c0})
	/opt/homebrew/Cellar/go/1.22.0/libexec/src/go/ast/walk.go:51 +0x44
go/ast.Walk({0x10094c400?, 0x1400ea05dd0?}, {0x10094ece0, 0x14015303260})
	/opt/homebrew/Cellar/go/1.22.0/libexec/src/go/ast/walk.go:85 +0x1e68
go/ast.Walk({0x10094c400?, 0x1400ea05d70?}, {0x10094ef60, 0x1401532a708})
	/opt/homebrew/Cellar/go/1.22.0/libexec/src/go/ast/walk.go:168 +0xdc8
github.com/sourcegraph/scip-go/internal/visitors.typeVisitor.Visit({0x1400e9dd110, 0x140004eb980, 0x1400ea02330, 0x14015311880, 0x0}, {0x10094ec90, 0x14015311440})
	/Users/qaisjp/go/pkg/mod/github.com/sourcegraph/scip-go@v0.1.12/internal/visitors/visitor_type.go:149 +0xe84
go/ast.Walk({0x10094c400?, 0x1400ea04990?}, {0x10094ec90, 0x14015311440})
	/opt/homebrew/Cellar/go/1.22.0/libexec/src/go/ast/walk.go:51 +0x44
go/ast.Walk({0x10094c400?, 0x1400ea04930?}, {0x10094ece0, 0x140153033e0})
	/opt/homebrew/Cellar/go/1.22.0/libexec/src/go/ast/walk.go:85 +0x1e68
go/ast.Walk({0x10094c400?, 0x1400ea048d0?}, {0x10094ef60, 0x1401532aaf8})
	/opt/homebrew/Cellar/go/1.22.0/libexec/src/go/ast/walk.go:168 +0xdc8
github.com/sourcegraph/scip-go/internal/visitors.typeVisitor.Visit({0x1400e9dd110, 0x140004eb980, 0x1400ea02330, 0x14015311880, 0x0}, {0x10094f370, 0x14015310c40})
	/Users/qaisjp/go/pkg/mod/github.com/sourcegraph/scip-go@v0.1.12/internal/visitors/visitor_type.go:94 +0x488
go/ast.Walk({0x10094c400?, 0x1400ea04810?}, {0x10094f370, 0x14015310c40})
	/opt/homebrew/Cellar/go/1.22.0/libexec/src/go/ast/walk.go:51 +0x44
github.com/sourcegraph/scip-go/internal/visitors.typeVisitor.Visit({0x1400e9dd110, 0x140004eb980, 0x1400ea02330, 0x0, 0x0}, {0x10094f3c0, 0x14015311880})
	/Users/qaisjp/go/pkg/mod/github.com/sourcegraph/scip-go@v0.1.12/internal/visitors/visitor_type.go:63 +0x4f0
go/ast.Walk({0x10094c400?, 0x1400e9dd1a0?}, {0x10094f3c0, 0x14015311880})
	/opt/homebrew/Cellar/go/1.22.0/libexec/src/go/ast/walk.go:51 +0x44
go/ast.walkDeclList(...)
	/opt/homebrew/Cellar/go/1.22.0/libexec/src/go/ast/walk.go:38
go/ast.Walk({0x10094c400?, 0x1400e9dd140?}, {0x10094e908, 0x14012e6cf00})
	/opt/homebrew/Cellar/go/1.22.0/libexec/src/go/ast/walk.go:366 +0x2e14
github.com/sourcegraph/scip-go/internal/visitors.visitTypesInFile(0x1400e9dd110, 0x140004eb980, 0x14012e6cf00)
	/Users/qaisjp/go/pkg/mod/github.com/sourcegraph/scip-go@v0.1.12/internal/visitors/visitor_type.go:19 +0x11c
github.com/sourcegraph/scip-go/internal/visitors.visitSyntax(0x140004eb980, 0x1400ad46320, 0x14012e6cf00, {0x1400003ed3b, 0xb})
	/Users/qaisjp/go/pkg/mod/github.com/sourcegraph/scip-go@v0.1.12/internal/visitors/visitors.go:45 +0xd4
github.com/sourcegraph/scip-go/internal/visitors.VisitPackageSyntax({0x1400003b8c0, 0x1a}, 0x140004eb980, 0x1400bace2a0, 0x1400a90adf8)
	/Users/qaisjp/go/pkg/mod/github.com/sourcegraph/scip-go@v0.1.12/internal/visitors/visitors.go:30 +0x138
github.com/sourcegraph/scip-go/internal/index.indexVisitPackages.func1()
	/Users/qaisjp/go/pkg/mod/github.com/sourcegraph/scip-go@v0.1.12/internal/index/scip.go:191 +0xf8
created by github.com/sourcegraph/scip-go/internal/index.indexVisitPackages in goroutine 1
	/Users/qaisjp/go/pkg/mod/github.com/sourcegraph/scip-go@v0.1.12/internal/index/scip.go:186 +0x220
scip-go  1.88s user 0.73s system 44% cpu 5.948 total

Reproduction steps

1. Clone https://github.com/rivo/tview (HEAD as of writing is rivo/tview@0d02bb7)
2. Run scip-go

Additional context

The panic is happening here:

scip-go/internal/lookup/lookup.go

Lines 47 to 56 in a5b080c

	func (p *Package) Set(pos token.Pos, symbol *scip.SymbolInformation) {
	// TODO: Could remove this once we are 100% confident we're not overlapping...
	if original, ok := p.fields[pos]; ok {
	if original != symbol {
	panic(fmt.Sprintf("Cannot add pos to new symbol: %s %s", original, symbol))
	}
	}
	p.fields[pos] = symbol
	}

It's caused by these lines:

 // The cursor always points to the next position where a new character would
 // be placed. The selection start is the same as cursor as long as there is
 // no selection. When there is one, the selection is between selectionStart
 // and cursor.
 cursor, selectionStart struct {
  // The row and column in screen space but relative to the start of the
  // text which may be outside the text area's box. The column value may
  // be larger than where the cursor actually is if the line the cursor
  // is on is shorter. The actualColumn is the position as it is seen on
  // screen. These three values may not be determined yet, in which case
  // the row is negative.
  row, column, actualColumn int
  
  // The textAreaSpan position with state for the actual next character.
  pos [3]int
 }

The following patch makes the error go away:

diff --git a/textarea.go b/textarea.go
index e6452e3c..116c7439 100644
--- a/textarea.go
+++ b/textarea.go
@@ -89,6 +89,19 @@ type textAreaUndoItem struct {
 	continuation                  bool   // If true, this item is a continuation of the previous undo item. It is handled together with all other undo items in the same continuation sequence.
 }
 
+type cursorOrSelectionStart struct {
+	// The row and column in screen space but relative to the start of the
+	// text which may be outside the text area's box. The column value may
+	// be larger than where the cursor actually is if the line the cursor
+	// is on is shorter. The actualColumn is the position as it is seen on
+	// screen. These three values may not be determined yet, in which case
+	// the row is negative.
+	row, column, actualColumn int
+
+	// The textAreaSpan position with state for the actual next character.
+	pos [3]int
+}
+
 // TextArea implements a simple text editor for multi-line text. Multi-color
 // text is not supported. Word-wrapping is enabled by default but can be turned
 // off or be changed to character-wrapping.
@@ -284,18 +297,8 @@ type TextArea struct {
 	// be placed. The selection start is the same as the cursor as long as there
 	// is no selection. When there is one, the selection is between
 	// selectionStart and cursor.
-	cursor, selectionStart struct {
-		// The row and column in screen space but relative to the start of the
-		// text which may be outside the text area's box. The column value may
-		// be larger than where the cursor actually is if the line the cursor
-		// is on is shorter. The actualColumn is the position as it is seen on
-		// screen. These three values may not be determined yet, in which case
-		// the row is negative.
-		row, column, actualColumn int
-
-		// The textAreaSpan position with state for the actual next character.
-		pos [3]int
-	}
+	cursor         cursorOrSelectionStart
+	selectionStart cursorOrSelectionStart
 
 	// The minimum width of text (if available) to be shown left of the cursor.
 	minCursorPrefix int

[varungandhi-src]

Thanks for the detailed bug report, this panic should not longer be hit in https://github.com/sourcegraph/scip-go/releases/tag/v0.1.13