[Console] Make ConsoleSectionOutput::overwrite() atomic

Amoifr · nicolas-grekas · commit 997de0a2c0a1 · 2026-05-11T17:23:14.000+02:00
diff --git a/Output/ConsoleSectionOutput.php b/Output/ConsoleSectionOutput.php
@@ -88,8 +88,31 @@ public function clear(?int $lines = null)
      */
     public function overwrite(string|iterable $message)
     {
-        $this->clear();
-        $this->writeln($message);
+        if (!$this->content || !$this->isDecorated()) {
+            $this->writeln($message);
+
+            return;
+        }
+
+        // Replace own content and write everything in a single cursor-up + erase
+        // pass, to avoid the flicker (and the line-eating artifacts on some
+        // terminals) caused by calling clear() then writeln() back-to-back.
+        $linesCleared = $this->lines;
+        $this->content = [];
+        $this->lines = 0;
+
+        if (!is_iterable($message)) {
+            $message = [$message];
+        }
+
+        foreach ($message as $line) {
+            $this->addContent($line, true);
+        }
+
+        $erasedContent = $this->popStreamContentUntilCurrentSection($this->maxHeight ? min($this->maxHeight, $linesCleared) : $linesCleared);
+
+        parent::doWrite($this->getVisibleContent(), false);
+        parent::doWrite($erasedContent, false);
     }
 
     public function getContent(): string
diff --git a/Tests/Output/ConsoleSectionOutputTest.php b/Tests/Output/ConsoleSectionOutputTest.php
@@ -200,6 +200,20 @@ public function testOverwriteMultipleLines()
         $this->assertEquals('Foo'.\PHP_EOL.'Bar'.\PHP_EOL.'Baz'.\PHP_EOL.\sprintf("\x1b[%dA", 3)."\x1b[0J".'Bar'.\PHP_EOL, stream_get_contents($output->getStream()));
     }
 
+    public function testOverwriteWithMaxHeightOverflow()
+    {
+        $sections = [];
+        $output = new ConsoleSectionOutput($this->stream, $sections, OutputInterface::VERBOSITY_NORMAL, true, new OutputFormatter());
+        $output->setMaxHeight(2);
+
+        $output->writeln(['One', 'Two']);
+        // overwrite with more lines than the max height: only the last lines stay visible
+        $output->overwrite('A'.\PHP_EOL.'B'.\PHP_EOL.'C');
+
+        rewind($output->getStream());
+        $this->assertEquals('One'.\PHP_EOL.'Two'.\PHP_EOL."\x1b[2A\x1b[0J".'B'.\PHP_EOL.'C'.\PHP_EOL, stream_get_contents($output->getStream()));
+    }
+
     public function testAddingMultipleSections()
     {
         $sections = [];
@@ -223,7 +237,7 @@ public function testMultipleSectionsOutput()
         $output2->overwrite('Foobar');
 
         rewind($output->getStream());
-        $this->assertEquals('Foo'.\PHP_EOL.'Bar'.\PHP_EOL."\x1b[2A\x1b[0JBar".\PHP_EOL."\x1b[1A\x1b[0JBaz".\PHP_EOL.'Bar'.\PHP_EOL."\x1b[1A\x1b[0JFoobar".\PHP_EOL, stream_get_contents($output->getStream()));
+        $this->assertEquals('Foo'.\PHP_EOL.'Bar'.\PHP_EOL."\x1b[2A\x1b[0JBaz".\PHP_EOL.'Bar'.\PHP_EOL."\x1b[1A\x1b[0JFoobar".\PHP_EOL, stream_get_contents($output->getStream()));
     }
 
     public function testMultipleSectionsOutputWithoutNewline()
