internal/refactor/inline: less hacky solution for eliding braces

Joint with Alan Donovan (CL 535455) :)

For golang/go#63534

Change-Id: Ia4fdc617edf6699da285f56670a51efac1817834
Reviewed-on: https://go-review.googlesource.com/c/tools/+/534918
Reviewed-by: Alan Donovan <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>

Author: findleyr

gopls/internal/regtest/marker/testdata/codeaction/removeparam.txt

@@ -145,17 +145,13 @@ func _() {
 	Ellipsis()
 	Ellipsis()
 	Ellipsis()
-
 	var _ []any = []any{1, f(), g()}
 	Ellipsis()
-
 	func(_ ...any) {
 		Ellipsis()
 	}(h())
-
 	var _ []any = i()
 	Ellipsis()
-
 }
 
 func f() int
@@ -228,10 +224,8 @@ func f() int
 func g() int
 
 func _() {
-
 	var x, _ int = f(), g()
 	effects(x)
-
 	{
 		var x, _ int = f(), g()
 		effects(x)

gopls/internal/regtest/marker/testdata/codeaction/removeparam_imports.txt

@@ -89,10 +89,8 @@ import (
 )
 
 func _() {
-
 	var _ c.C = <-b.Chan
 	b.B(<-b.Chan)
-
 }
 -- @b/a/a2.go --
 package a
@@ -103,13 +101,10 @@ import (
 )
 
 func _() {
-
 	var _ c.C = <-b.Chan
 	b.B(<-b.Chan)
-
 	var _ c.C = <-b.Chan
 	b.B(<-b.Chan)
-
 }
 -- @b/a/a3.go --
 package a
@@ -120,17 +115,13 @@ import (
 )
 
 func _() {
-
 	var _ c.C = <-b.Chan
 	b.B(<-b.Chan)
-
 }
 
 func _() {
-
 	var _ c.C = <-b.Chan
 	b.B(<-b.Chan)
-
 }
 -- @b/a/a4.go --
 package a
@@ -144,10 +135,8 @@ import (
 )
 
 func _() {
-
 	var _ c.C = <-Chan
 	b.B(<-Chan)
-
 }
 -- @b/b/b.go --
 package b

internal/refactor/inline/inline.go

@@ -183,15 +183,19 @@ func Inline(logf func(string, ...any), caller *Caller, callee *Callee) ([]byte,
 		// Precise comment handling would make this a
 		// non-issue. Formatting wouldn't really need a
 		// FileSet at all.
-		mark := out.Len()
-		if err := format.Node(&out, caller.Fset, res.new); err != nil {
-			return nil, err
-		}
 		if elideBraces {
-			// Overwrite unnecessary {...} braces with spaces.
-			// TODO(adonovan): less hacky solution.
-			out.Bytes()[mark] = ' '
-			out.Bytes()[out.Len()-1] = ' '
+			for i, stmt := range res.new.(*ast.BlockStmt).List {
+				if i > 0 {
+					out.WriteByte('\n')
+				}
+				if err := format.Node(&out, caller.Fset, stmt); err != nil {
+					return nil, err
+				}
+			}
+		} else {
+			if err := format.Node(&out, caller.Fset, res.new); err != nil {
+				return nil, err
+			}
 		}
 		out.Write(caller.Content[end:])
 		const mode = parser.ParseComments | parser.SkipObjectResolution | parser.AllErrors
@@ -902,9 +906,6 @@ func inline(logf func(string, ...any), caller *Caller, callee *gobCallee) (*resu
 	// The body may use defer, arbitrary control flow, and
 	// multiple returns.
 	//
-	// TODO(adonovan): omit the braces if the sets of
-	// names in the two blocks are disjoint.
-	//
 	// TODO(adonovan): add a strategy for a 'void tail
 	// call', i.e. a call statement prior to an (explicit
 	// or implicit) return.
@@ -942,8 +943,6 @@ func inline(logf func(string, ...any), caller *Caller, callee *gobCallee) (*resu
 	// - all parameters and result vars can be eliminated
 	//   or replaced by a binding decl,
 	// - caller ExprStmt is in unrestricted statement context.
-	//
-	// If there is only a single statement, the braces are omitted.
 	if stmt := callStmt(caller.path, true); stmt != nil &&
 		(!needBindingDecl || bindingDeclStmt != nil) &&
 		!callee.HasDefer &&
@@ -956,9 +955,6 @@ func inline(logf func(string, ...any), caller *Caller, callee *gobCallee) (*resu
 		if needBindingDecl {
 			body.List = prepend(bindingDeclStmt, body.List...)
 		}
-		if len(body.List) == 1 { // FIXME do this opt later
-			repl = body.List[0] // singleton: omit braces
-		}
 		res.old = stmt
 		res.new = repl
 		return res, nil

internal/refactor/inline/testdata/import-shadow.txtar

@@ -87,10 +87,8 @@ import (
 var x b.T
 
 func A(b int) {
-
 	b0.One()
-	b0.Two()
-	//@ inline(re"F", fresult)
+	b0.Two() //@ inline(re"F", fresult)
 }
 
 -- d/d.go --

internal/refactor/inline/testdata/issue63298.txtar

@@ -45,8 +45,6 @@ import (
 )
 
 func _() {
-
 	b.B()
 	b0.B()
-
-}
+}

internal/refactor/inline/testdata/method.txtar

@@ -104,10 +104,8 @@ func (T) h() int { return 1 }
 
 func _() {
 	var ptr *T
-
 	var _ T = *ptr
-	_ = 1
-	//@ inline(re"h", h)
+	_ = 1 //@ inline(re"h", h)
 }
 
 -- a/i.go --

internal/refactor/inline/testdata/multistmt-body.txtar

@@ -54,10 +54,8 @@ package a
 
 func _() {
 	a := 1
-
 	z := 1
-	print(a + 2 + z)
-	//@ inline(re"f", out2)
+	print(a + 2 + z) //@ inline(re"f", out2)
 }
 
 -- a/a3.go --

internal/refactor/inline/testdata/tailcall.txtar

@@ -36,7 +36,6 @@ start:
 package a
 
 func _() int {
-
 	total := 0
 start:
 	for i := 1; i <= 2; i++ {
@@ -47,8 +46,7 @@ start:
 			return -1
 		}
 	}
-	return total
-	//@ inline(re"sum", sum)
+	return total //@ inline(re"sum", sum)
 }
 
 func sum(lo, hi int) int {