Keep line numbers after a multi-line self-closing component

blank.ts

@@ -1144,7 +1144,10 @@ function substituteSelfClosingComponent(
   if (sourceLen < minLen) {
     return false;
   }
-  const inner = ' '.repeat(sourceLen - minLen);
+  // Keep the span's newlines inside the element, so later lines keep
+  // their line numbers.
+  const newlines = ctx.content.slice(elementStart, elementEnd).replace(/[^\r\n]/g, '').slice(0, sourceLen - minLen);
+  const inner = newlines + ' '.repeat(sourceLen - minLen - newlines.length);
   ctx.renames.push([elementStart, elementEnd, openTag + inner + closeTag]);
   ctx.fullyBlankedRanges.push([elementStart, elementEnd]);
   ctx.dynamicContentOffsets.push(elementStart);

examples/multiline-self-closing-consumer.gts

@@ -0,0 +1,14 @@
+// The self-closing call spans five lines. The untyped `<button>` after
+// it must be reported on its own source line.
+import InfoPopover from '../test/glint-fixtures/info-popover-leaf.gts';
+
+<template>
+  <section>
+    <InfoPopover
+      @popoverId='equipment-info-popover-for-the-selected-row'
+      @label='Details about the equipment in the selected row of the table'
+      class='mt-2'
+    />
+    <button>Save</button>
+  </section>
+</template>

test/glint-fixtures/info-popover-leaf.gts

@@ -0,0 +1,17 @@
+// A non-void root with a long literal open tag. A self-closing call
+// substitutes to `<div popover='auto' class='…'></div>`, which is longer
+// than the first line of a multi-line call.
+import type { TemplateOnlyComponent } from '@ember/component/template-only';
+
+interface InfoPopoverSig {
+  Element: HTMLDivElement;
+  Args: { popoverId: string; label: string };
+}
+
+const InfoPopover: TemplateOnlyComponent<InfoPopoverSig> = <template>
+  <div popover='auto' id={{@popoverId}} class='m-0 w-72 rounded-xl bg-white p-4 text-sm text-gray-900' ...attributes>
+    {{@label}}
+  </div>
+</template>;
+
+export default InfoPopover;

test/integration.test.ts

@@ -262,6 +262,19 @@ describe('end-to-end fixtures', () => {
     }
   });
 
+  it.each(['1', '0'])('multiline-self-closing-consumer: a substituted self-closing call keeps its newlines, so later errors report the source line (HVE_GLINT=%s)', async (glint) => {
+    const prevGlint = process.env['HVE_GLINT'];
+    process.env['HVE_GLINT'] = glint;
+    try {
+      const r = await validate('multiline-self-closing-consumer.gts');
+      const buttonType = r.messages.filter((m) => m.rule === 'no-implicit-button-type');
+      expect(buttonType.map((m) => `${m.line}:${m.column}`), JSON.stringify(r.messages)).toEqual(['12:6']);
+    } finally {
+      if (prevGlint === undefined) delete process.env['HVE_GLINT'];
+      else process.env['HVE_GLINT'] = prevGlint;
+    }
+  });
+
   it('multi-yield-table-consumer: wrapper with multi-yield template (different ancestors per named block) substitutes to outer wrapper, not first yield-ancestor', async () => {
     // Mirrors HDS `<HdsTable>` shape — its template yields to BOTH
     // `to="head"` (inside `<thead>`) and `to="body"` (inside