From b5ca90eb708492c2d0c8ae4cc18d9cf2b09a3c35 Mon Sep 17 00:00:00 2001
From: Wleeaf <179125857+wleeaf@users.noreply.github.com>
Date: Sun, 25 Oct 2026 16:17:40 +0000
Subject: [PATCH] fix: keep trailing whitespace in heredoc and nowdoc bodies

Flexible heredocs and nowdocs (PHP >= 7.3) are re-indented with
`hardline`, and the doc printer trims trailing spaces and tabs before
every `hardline`. That whitespace is part of the string, so formatting
changed the value: `foo   ` became `foo`, and a whitespace-only line
became empty.

After a line that ends in whitespace, use a `literalline` under
`markAsRoot` instead, so the next line keeps the same indentation and
nothing is trimmed. Other lines still use `hardline`, so output is
unchanged for heredocs without trailing whitespace.
---
 src/printer.mjs                               | 46 ++++++----
 .../__snapshots__/jsfmt.spec.mjs.snap         | 90 +++++++++++++++++++
 .../encapsed/heredoc-trailing-whitespace.php  | 16 ++++
 .../nowdoc/__snapshots__/jsfmt.spec.mjs.snap  | 82 +++++++++++++++++
 tests/nowdoc/trailing-whitespace.php          | 14 +++
 5 files changed, 231 insertions(+), 17 deletions(-)
 create mode 100644 tests/encapsed/heredoc-trailing-whitespace.php
 create mode 100644 tests/nowdoc/trailing-whitespace.php

diff --git a/src/printer.mjs b/src/printer.mjs
index a9f06c170..4645c6bc8 100644
--- a/src/printer.mjs
+++ b/src/printer.mjs
@@ -55,6 +55,7 @@ const {
   literalline,
   align,
   dedentToRoot,
+  markAsRoot,
 } = doc.builders;
 const { willBreak } = doc.utils;
 const {
@@ -866,6 +867,21 @@ function printLookupNodes(path, options, print) {
   }
 }
 
+/**
+ * Join the body lines of a flexible heredoc or nowdoc. `hardline` trims
+ * trailing whitespace, which is part of the string, so a line ending in
+ * whitespace is followed by a `literalline` that keeps the indentation.
+ */
+function joinHeredocLines(lines) {
+  return markAsRoot(
+    lines.flatMap((line, index) =>
+      index === 0
+        ? [line]
+        : [/[\t ]$/.test(lines[index - 1]) ? literalline : hardline, line]
+    )
+  );
+}
+
 function getEncapsedQuotes(node, { opening = true } = {}) {
   if (node.type === "heredoc") {
     return opening ? `<<<${node.label}` : node.label;
@@ -2866,25 +2882,23 @@ function printNode(path, options, print) {
         const parentParent = path.grandparent;
         let closingTagIndentation = 0;
         const flexible = options.phpVersion >= 7.3;
-        let linebreak = literalline;
         if (parentParent.type === "heredoc") {
-          linebreak = flexible ? hardline : literalline;
           const lines = parentParent.raw.split("\n");
           closingTagIndentation = lines[lines.length - 1].search(/\S/);
           if (closingTagIndentation === -1) {
             closingTagIndentation = lines[lines.length - 2].search(/\S/);
           }
         }
-        return join(
-          linebreak,
-          node.raw
-            .split("\n")
-            .map((s, i) =>
-              i > 0 || node.loc.start.column === 0
-                ? s.substring(closingTagIndentation)
-                : s
-            )
-        );
+        const valueLines = node.raw
+          .split("\n")
+          .map((s, i) =>
+            i > 0 || node.loc.start.column === 0
+              ? s.substring(closingTagIndentation)
+              : s
+          );
+        return parentParent.type === "heredoc" && flexible
+          ? joinHeredocLines(valueLines)
+          : join(literalline, valueLines);
       }
 
       const quote = useDoubleQuote(node, options) ? '"' : "'";
@@ -2960,15 +2974,13 @@ function printNode(path, options, print) {
       return node.value;
     case "nowdoc": {
       const flexible = options.phpVersion >= 7.3;
-      const linebreak = flexible ? hardline : literalline;
+      const lines = [...node.value.split("\n"), node.label];
       return [
         "<<<'",
         node.label,
         "'",
-        linebreak,
-        join(linebreak, node.value.split("\n")),
-        linebreak,
-        node.label,
+        flexible ? hardline : literalline,
+        flexible ? joinHeredocLines(lines) : join(literalline, lines),
         docShouldHaveTrailingNewline(path) ? hardline : "",
       ];
     }
diff --git a/tests/encapsed/__snapshots__/jsfmt.spec.mjs.snap b/tests/encapsed/__snapshots__/jsfmt.spec.mjs.snap
index 0b8acbec2..bca3eb23f 100644
--- a/tests/encapsed/__snapshots__/jsfmt.spec.mjs.snap
+++ b/tests/encapsed/__snapshots__/jsfmt.spec.mjs.snap
@@ -2077,6 +2077,96 @@ printf(
 ================================================================================
 `;
 
+exports[`heredoc-trailing-whitespace.php 1`] = `
+====================================options=====================================
+parsers: ["php"]
+phpVersion: "7.0"
+printWidth: 80
+                                                                                | printWidth
+=====================================input======================================
+<?php
+$a = <<<EOT
+foo   
+bar	
+  
+EOT;
+
+function f()
+{
+    $b = <<<EOT
+        foo   
+          
+        {$c}  
+        bar	
+        EOT;
+}
+
+=====================================output=====================================
+<?php
+$a = <<<EOT
+foo   
+bar	
+  
+EOT;
+
+function f()
+{
+    $b = <<<EOT
+foo   
+  
+{$c}  
+bar	
+EOT;
+}
+
+================================================================================
+`;
+
+exports[`heredoc-trailing-whitespace.php 2`] = `
+====================================options=====================================
+parsers: ["php"]
+phpVersion: "7.3"
+printWidth: 80
+                                                                                | printWidth
+=====================================input======================================
+<?php
+$a = <<<EOT
+foo   
+bar	
+  
+EOT;
+
+function f()
+{
+    $b = <<<EOT
+        foo   
+          
+        {$c}  
+        bar	
+        EOT;
+}
+
+=====================================output=====================================
+<?php
+$a = <<<EOT
+foo   
+bar	
+  
+EOT;
+
+function f()
+{
+    $b = <<<EOT
+    foo   
+      
+    {$c}  
+    bar	
+    EOT;
+}
+
+================================================================================
+`;
+
 exports[`single.php 1`] = `
 ====================================options=====================================
 parsers: ["php"]
diff --git a/tests/encapsed/heredoc-trailing-whitespace.php b/tests/encapsed/heredoc-trailing-whitespace.php
new file mode 100644
index 000000000..91dc47a56
--- /dev/null
+++ b/tests/encapsed/heredoc-trailing-whitespace.php
@@ -0,0 +1,16 @@
+<?php
+$a = <<<EOT
+foo   
+bar	
+  
+EOT;
+
+function f()
+{
+    $b = <<<EOT
+        foo   
+          
+        {$c}  
+        bar	
+        EOT;
+}
diff --git a/tests/nowdoc/__snapshots__/jsfmt.spec.mjs.snap b/tests/nowdoc/__snapshots__/jsfmt.spec.mjs.snap
index 3a9942819..10f46c099 100644
--- a/tests/nowdoc/__snapshots__/jsfmt.spec.mjs.snap
+++ b/tests/nowdoc/__snapshots__/jsfmt.spec.mjs.snap
@@ -4193,3 +4193,85 @@ EOD;
 
 ================================================================================
 `;
+
+exports[`trailing-whitespace.php 1`] = `
+====================================options=====================================
+parsers: ["php"]
+phpVersion: "7.0"
+printWidth: 80
+                                                                                | printWidth
+=====================================input======================================
+<?php
+$a = <<<'EOT'
+foo   
+bar	
+EOT;
+
+function f()
+{
+    $b = <<<'EOT'
+        foo   
+          
+        bar	
+        EOT;
+}
+
+=====================================output=====================================
+<?php
+$a = <<<'EOT'
+foo   
+bar	
+EOT;
+
+function f()
+{
+    $b = <<<'EOT'
+foo   
+  
+bar	
+EOT;
+}
+
+================================================================================
+`;
+
+exports[`trailing-whitespace.php 2`] = `
+====================================options=====================================
+parsers: ["php"]
+phpVersion: "7.3"
+printWidth: 80
+                                                                                | printWidth
+=====================================input======================================
+<?php
+$a = <<<'EOT'
+foo   
+bar	
+EOT;
+
+function f()
+{
+    $b = <<<'EOT'
+        foo   
+          
+        bar	
+        EOT;
+}
+
+=====================================output=====================================
+<?php
+$a = <<<'EOT'
+foo   
+bar	
+EOT;
+
+function f()
+{
+    $b = <<<'EOT'
+    foo   
+      
+    bar	
+    EOT;
+}
+
+================================================================================
+`;
diff --git a/tests/nowdoc/trailing-whitespace.php b/tests/nowdoc/trailing-whitespace.php
new file mode 100644
index 000000000..b6d3b83f0
--- /dev/null
+++ b/tests/nowdoc/trailing-whitespace.php
@@ -0,0 +1,14 @@
+<?php
+$a = <<<'EOT'
+foo   
+bar	
+EOT;
+
+function f()
+{
+    $b = <<<'EOT'
+        foo   
+          
+        bar	
+        EOT;
+}