commit 4ca49954c3f2dca17746a9bd2d3f253c4849d9ee
author Dmitri Shuralyov <dmitshur@golang.org> Mon Nov 05 17:36:47 2018 -0500
committer Dmitri Shuralyov <dmitshur@golang.org> Wed Nov 07 22:33:19 2018 +0000
tree 5d3140c8ed0202c5ccf682ef26b6af981e86b77f
parent 34b416bd17b3a33e02879e34237e92c171550ed5

go/ast/astutil: allow AddNamedImport to add imports with different names

This change makes AddNamedImport more symmetrical to DeleteNamedImport
in behavior, signature, and documentation.

In Go, it is valid to import a package (identified by an import path)
with different names in a single .go file¹. For example, this is ok,
and the program will build as long as there are no unused imports²:

	import (
		"path"
		. "path"
		_ "path"
		pathpkg "path"
	)

The four imports (represented by ast.ImportSpec type) have the same
import path, but different names.

It's currently possible to use DeleteNamedImport to delete the exact
{name, import path} ast.ImportSpec from an AST.

Previously, it wasn't possible to use AddNamedImport to add an exact
{name, import path} ast.ImportSpec if the AST already has another
ast.ImportSpec with the same import path (but different name).
This change fixes that, making it possible to use AddNamedImport as
expected.

Rename the ipath parameter to path in AddNamedImport for consistency
with DeleteNamedImport. Also change the language used in its
documentation to be more precise and consistent with DeleteNamedImport.

Add test cases for this behavior. The DeleteNamedImport test cases
were passing before any changes to the astutil code.

Add test coverage for the return bool value of {Add,Delete}NamedImport.
Document the behavior of DeleteNamedImport when there are duplicate
matching imports.

Simplify string(buf.Bytes()) to buf.String() in test helper code.

¹ https://golang.org/ref/spec#Import_declarations
² https://play.golang.org/p/bi6L34rQbcD

Fixes golang/go#28605
Fixes golang/go#16411

Change-Id: I70e887f5174764ab1cf32a761c8c734e216eea67
Reviewed-on: https://go-review.googlesource.com/c/147448
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alan Donovan <adonovan@google.com>