Rectify differences between lsp.DocumentSymbol and lsif.RangeBasedDocumentSymbol

[beyang]

LSIF defines DocumentSymbolResult like this:

export interface DocumentSymbolResult extends V {

  label: 'documentSymbolResult';

  result: lsp.DocumentSymbol[] | RangeBasedDocumentSymbol[];
}

Note the choice between lsp.DocumentSymbol or RangeBasedDocumentSymbol. The latter points to a range that includes one of DeclarationTag, DefinitionTag, ReferenceTag or UnknownTag.

There is some information that is present in lsp.DocumentSymbol that doesn't appear to be able to be reconstructed from RangeBasedDocumentSymbol and the range tag:

1. lsp.DocumentSymbol contains a tags?: SymbolTag[] field, which isn't present in any of the range tags.
2. lsp.DocumentSymbol includes a name: string field while DefinitionTag and DeclarationTag include a text: string field.

Proposal 1: Add a field tags?: Symbol[] to DefinitionTag and DeclarationTag so that this information is present for symbols when a LSIF indexer chooses to use the RangeBasedDocumentSymbol-based representation.

Proposal 2: Add a name: string field to DefinitionTag and DeclarationTag or else rename the text: string field in these interfaces to name.

[dbaeumer]

Having a symbol tag makes sense. And we should document that name === text. There needs to be some transformation anyways from a RangeBasedDocumentSymbol to a DocumentSymbol.