From f60b01540566ed00560987db5198a5f77ee75a79 Mon Sep 17 00:00:00 2001
From: Dave Cunningham <sparkprime@gmail.com>
Date: Tue, 21 Dec 2021 11:51:56 +0000
Subject: [PATCH] Corresponding change to formatter, see
 https://github.com/google/jsonnet/pull/937

---
 internal/formatter/jsonnetfmt.go |  9 +++++++-
 internal/formatter/unparser.go   | 37 +++++++++++++++++++++-----------
 2 files changed, 33 insertions(+), 13 deletions(-)

diff --git a/internal/formatter/jsonnetfmt.go b/internal/formatter/jsonnetfmt.go
index 5007921..bdc6f5f 100644
--- a/internal/formatter/jsonnetfmt.go
+++ b/internal/formatter/jsonnetfmt.go
@@ -134,6 +134,12 @@ func removeInitialNewlines(node ast.Node) {
 	}
 }
 
+func removeExtraTrailingNewlines(finalFodder ast.Fodder) {
+	if len(finalFodder) > 0 {
+		finalFodder[len(finalFodder)-1].Blanks = 0
+	}
+}
+
 func visitFile(p pass.ASTPass, node *ast.Node, finalFodder *ast.Fodder) {
 	p.File(p, node, finalFodder)
 }
@@ -183,10 +189,11 @@ func Format(filename string, input string, options Options) (string, error) {
 		visitor := FixIndentation{Options: options}
 		visitor.VisitFile(node, finalFodder)
 	}
+	removeExtraTrailingNewlines(finalFodder)
 
 	u := &unparser{options: options}
 	u.unparse(node, false)
-	u.fill(finalFodder, true, false)
+	u.fillFinal(finalFodder, true, false)
 	// Final whitespace is stripped at lexing time.  Add a single new line
 	// as files ought to end with a new line.
 	u.write("\n")
diff --git a/internal/formatter/unparser.go b/internal/formatter/unparser.go
index f126a8b..ccddabd 100644
--- a/internal/formatter/unparser.go
+++ b/internal/formatter/unparser.go
@@ -50,9 +50,10 @@ func (u *unparser) write(str string) {
 // creates a crowded situation where there was not one before).
 // If crowded is false and separateToken is false then no space is printed
 // after or before the fodder, even if the last fodder was an interstitial.
-func (u *unparser) fill(fodder ast.Fodder, crowded bool, separateToken bool) {
+func (u *unparser) fodderFill(fodder ast.Fodder, crowded bool, separateToken bool, final bool) {
 	var lastIndent int
-	for _, fod := range fodder {
+	for i, fod := range fodder {
+		skipTrailing := final && (i == (len(fodder) - 1))
 		switch fod.Kind {
 		case ast.FodderParagraph:
 			for i, l := range fod.Comment {
@@ -68,11 +69,13 @@ func (u *unparser) fill(fodder ast.Fodder, crowded bool, separateToken bool) {
 				}
 				u.write("\n")
 			}
-			for i := 0; i < fod.Blanks; i++ {
-				u.write("\n")
-			}
-			for i := 0; i < fod.Indent; i++ {
-				u.write(" ")
+			if !skipTrailing {
+				for i := 0; i < fod.Blanks; i++ {
+					u.write("\n")
+				}
+				for i := 0; i < fod.Indent; i++ {
+					u.write(" ")
+				}
 			}
 			lastIndent = fod.Indent
 			crowded = false
@@ -82,11 +85,13 @@ func (u *unparser) fill(fodder ast.Fodder, crowded bool, separateToken bool) {
 				u.write("  ")
 				u.write(fod.Comment[0])
 			}
-			for i := 0; i <= fod.Blanks; i++ {
-				u.write("\n")
-			}
-			for i := 0; i < fod.Indent; i++ {
-				u.write(" ")
+			if !skipTrailing {
+				for i := 0; i <= fod.Blanks; i++ {
+					u.write("\n")
+				}
+				for i := 0; i < fod.Indent; i++ {
+					u.write(" ")
+				}
 			}
 			lastIndent = fod.Indent
 			crowded = false
@@ -104,6 +109,14 @@ func (u *unparser) fill(fodder ast.Fodder, crowded bool, separateToken bool) {
 	}
 }
 
+func (u *unparser) fill(fodder ast.Fodder, crowded bool, separateToken bool) {
+	u.fodderFill(fodder, crowded, separateToken, false)
+}
+
+func (u *unparser) fillFinal(fodder ast.Fodder, crowded bool, separateToken bool) {
+	u.fodderFill(fodder, crowded, separateToken, true)
+}
+
 func (u *unparser) unparseSpecs(spec *ast.ForSpec) {
 	if spec.Outer != nil {
 		u.unparseSpecs(spec.Outer)