tree 83500044813d278ed80e8a94dcddd69216892750
parent 2b6af5f9ace725aefaab9e4e3abbcdd9f07ef5bc
author Muir Manders <muir@mnd.rs> 1574277353 -0800
committer Rebecca Stambler <rstambler@golang.org> 1575347402 +0000

internal/lsp: improve completion after accidental keywords

Sometimes the prefix of the thing you want to complete is a keyword.
For example:

variance := 123
fmt.Println(var<>)

In this case the parser produces an *ast.BadExpr which breaks
completion. We now repair this BadExpr by replacing it with
an *ast.Ident named "var".

We also repair empty decls using a similar approach. This fixes cases
like:

var typeName string
type<> // want to complete to "typeName"

We also fix accidental keywords in selectors, such as:

foo.var<>

The parser produces a phantom "_" in place of the keyword, so we swap
it back for an *ast.Ident named "var".

In general, though, accidental keywords wreak havoc on the AST so we
can only do so much. There are still many cases where a keyword prefix
breaks completion. Perhaps in the future the parser can be
cursor/in-progress-edit aware and turn accidental keywords into
identifiers.

Fixes golang/go#34332.

PS I tweaked nodeContains() to include n.End() to fix a test failure
against tip related to a change to go/parser. When a syntax error is
present, an *ast.BlockStmt's End() is now set to the block's final
statement's End() (earlier than what it used to be). In order for the
cursor pos to test "inside" the block in this case I had to relax the
End() comparison.

Change-Id: Ib45952cf086cc974f1578298df3dd12829344faa
Reviewed-on: https://go-review.googlesource.com/c/tools/+/209438
Run-TryBot: Muir Manders <muir@mnd.rs>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>