When using the \page command with file extensions other than .html (e.g., .htm, .xml, .txt, .pdf, .json), QDoc incorrectly generates output files with double extensions by preserving the original extension and appending .html. QDoc's file generation logic fails to recognize and remove the extension, resulting in malformed output filenames with double extensions.

The issue is in src/qttools/src/qdoc/qdoc/src/qdoc/generator.cpp in the fileBase() function (lines 263-264):

QString base{node->name()};
if (base.endsWith(".html"))
    base.truncate(base.size() - 5);

The code only checks for and removes .html extensions, but not other common extensions. When a page has a different extension, it gets treated as part of the base name, and then .html is appended, creating the double extension.

Steps to Reproduce

A test case demonstrating this issue already exists in:
src/qttools/src/qdoc/qdoc/tests/validateqdocoutputfiles/testdata/non_ascii_character_input/src/adventures_with_non_ascii_characters.qdoc (line 57).

Expected Behavior

QDoc should either:
1. Respect the specified extension and generate files with the exact extension provided (e.g., `test.htm` generates `test.htm`)
2. OR consistently replace any extension with `.html` (e.g., `test.htm` generates `test.html`)

The current behavior of creating double extensions is clearly incorrect.

Impact

• Breaks expected file naming conventions
• Can cause issues with links and references to generated documentation
• Affects all file extensions except `.html`

Suggested Fix

The fileBase() function should be updated to handle all common file extensions, not just .html. A possible approach:

QString base{node->name()};
// Remove any known file extension
static const QStringList extensions = {".html", ".htm", ".xml", ".txt", ".pdf", ".json"};
for (const QString &ext : extensions) {
    if (base.endsWith(ext))

Unknown macro: {         base.truncate(base.size() - ext.size());         break;     }

}

Or use a more generic approach with QFileInfo::completeBaseName().