From 990129eca5479318dfdf63957e7f4181c28cefce Mon Sep 17 00:00:00 2001
From: Muir Manders <muir@mnd.rs>
Date: Sat, 1 Aug 2020 14:18:10 -0700
Subject: [PATCH] internal/lsp/source: prefer funcs when completing go/defer

Now we prefer functions when completing "go" and "defer" statements.
Previously we had no preference for the type of object. Further, we
will now also properly invoke functions.

    var f1 int
    var f2 func()
    go f<> // prefers "f2" and expands to "f2()"

Change-Id: I213551b74ba453c337ac89e825b5d495659e9d65
Reviewed-on: https://go-review.googlesource.com/c/tools/+/246359
Run-TryBot: Muir Manders <muir@mnd.rs>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
---
 internal/lsp/source/completion.go              | 18 +++++++++++++++---
 .../lsp/primarymod/badstmt/badstmt_3.go.in     |  2 +-
 .../lsp/primarymod/badstmt/badstmt_4.go.in     |  2 +-
 .../lsp/primarymod/func_rank/func_rank.go.in   |  2 +-
 internal/lsp/testdata/lsp/summary.txt.golden   |  2 +-
 5 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/internal/lsp/source/completion.go b/internal/lsp/source/completion.go
index e4f32bd65d..c0362bee83 100644
--- a/internal/lsp/source/completion.go
+++ b/internal/lsp/source/completion.go
@@ -1511,6 +1511,7 @@ const (
 	kindMap
 	kindStruct
 	kindString
+	kindFunc
 )
 
 // candidateInference holds information we have inferred about a type that can be
@@ -1639,7 +1640,7 @@ Nodes:
 			return inf
 		case *ast.CallExpr:
 			// Only consider CallExpr args if position falls between parens.
-			if node.Lparen <= c.pos && c.pos <= node.Rparen {
+			if node.Lparen < c.pos && c.pos <= node.Rparen {
 				// For type conversions like "int64(foo)" we can only infer our
 				// desired type is convertible to int64.
 				if typ := typeConversion(node, c.pkg.GetTypesInfo()); typ != nil {
@@ -1709,8 +1710,9 @@ Nodes:
 						continue Nodes
 					}
 				}
+
+				return inf
 			}
-			return inf
 		case *ast.ReturnStmt:
 			if c.enclosingFunc != nil {
 				sig := c.enclosingFunc.sig
@@ -1775,6 +1777,9 @@ Nodes:
 			case token.ARROW:
 				inf.modifiers = append(inf.modifiers, typeModifier{mod: chanRead})
 			}
+		case *ast.DeferStmt, *ast.GoStmt:
+			inf.objKind |= kindFunc
+			return inf
 		default:
 			if breaksExpectedTypeInference(node) {
 				return inf
@@ -2137,7 +2142,12 @@ func (ci *candidateInference) candTypeMatches(cand *candidate) bool {
 
 			// If we have no expected type, fall back to checking the
 			// expected "kind" of object, if available.
-			return ci.kindMatches(candType)
+			if ci.kindMatches(candType) {
+				if ci.objKind == kindFunc {
+					cand.expandFuncCall = true
+				}
+				return true
+			}
 		}
 
 		for _, expType := range expTypes {
@@ -2326,6 +2336,8 @@ func candKind(candType types.Type) objKind {
 		if t.Info()&types.IsString > 0 {
 			return kindString
 		}
+	case *types.Signature:
+		return kindFunc
 	}
 
 	return 0
diff --git a/internal/lsp/testdata/lsp/primarymod/badstmt/badstmt_3.go.in b/internal/lsp/testdata/lsp/primarymod/badstmt/badstmt_3.go.in
index 66174095d7..be774e84b0 100644
--- a/internal/lsp/testdata/lsp/primarymod/badstmt/badstmt_3.go.in
+++ b/internal/lsp/testdata/lsp/primarymod/badstmt/badstmt_3.go.in
@@ -5,5 +5,5 @@ import (
 )
 
 func _() {
-	go foo. //@rank(" //", Foo)
+	go foo. //@rank(" //", Foo, IntFoo),snippet(" //", Foo, "Foo()", "Foo()")
 }
diff --git a/internal/lsp/testdata/lsp/primarymod/badstmt/badstmt_4.go.in b/internal/lsp/testdata/lsp/primarymod/badstmt/badstmt_4.go.in
index d6615812d6..a9b46fb021 100644
--- a/internal/lsp/testdata/lsp/primarymod/badstmt/badstmt_4.go.in
+++ b/internal/lsp/testdata/lsp/primarymod/badstmt/badstmt_4.go.in
@@ -6,6 +6,6 @@ import (
 
 func _() {
 	go func() {
-		defer foo. //@rank(" //", Foo)
+		defer foo. //@rank(" //", Foo, IntFoo)
 	}
 }
diff --git a/internal/lsp/testdata/lsp/primarymod/func_rank/func_rank.go.in b/internal/lsp/testdata/lsp/primarymod/func_rank/func_rank.go.in
index 9d180ad2c2..3706009583 100644
--- a/internal/lsp/testdata/lsp/primarymod/func_rank/func_rank.go.in
+++ b/internal/lsp/testdata/lsp/primarymod/func_rank/func_rank.go.in
@@ -27,7 +27,7 @@ func _() {
 
 	// no expected type
 	fnInt(func() int { s.A }) //@complete(" }", rankAA, rankAB, rankAC)
-	fnInt(s.A())              //@complete("()", rankAA, rankAB, rankAC)
+	fnInt(s.A())              //@complete("()", rankAA, rankAC, rankAB)
 	fnInt([]int{}[s.A])       //@complete("])", rankAA, rankAC, rankAB)
 	fnInt([]int{}[:s.A])      //@complete("])", rankAA, rankAC, rankAB)
 
diff --git a/internal/lsp/testdata/lsp/summary.txt.golden b/internal/lsp/testdata/lsp/summary.txt.golden
index ea87659ecc..91b872a5ae 100644
--- a/internal/lsp/testdata/lsp/summary.txt.golden
+++ b/internal/lsp/testdata/lsp/summary.txt.golden
@@ -1,7 +1,7 @@
 -- summary --
 CodeLensCount = 4
 CompletionsCount = 241
-CompletionSnippetCount = 80
+CompletionSnippetCount = 81
 UnimportedCompletionsCount = 6
 DeepCompletionsCount = 5
 FuzzyCompletionsCount = 8