From dfcc9bfb7cbffb9689221d14fbe5e89b587d98f7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Denis=20A=2E=20Alto=C3=A9=20Falqueto?=
 <denisfalqueto@gmail.com>
Date: Wed, 8 Jul 2026 10:45:59 -0300
Subject: [PATCH] Fixed #33341, #33559: robustify Linux PDF export against file
 dialog quirks

Two independent fixes for PDF export failing/crashing on Linux:

- src/app/main.cpp: only force QT_QPA_PLATFORMTHEME=gtk3 when the user
  hasn't already set it. gtk3 was forced unconditionally to fix keyboard
  input in the legacy Qt file dialog (#13113), but this also silently
  overrode any theme the user configured (e.g. "xdgdesktopportal" for
  proper portal/sandboxed dialog support), which is a likely contributor
  to file dialogs not respecting the user's desktop environment. The
  default (gtk3) is unchanged for users who don't set this variable, so
  #13113 is not reintroduced. QT_QPA_PLATFORM=xcb is left untouched, since
  it fixes unrelated Wayland issues (VST crashes #28446, panel docking
  #28352).

- src/project/internal/exportprojectscenario.cpp: after the file dialog
  returns a save path, force the expected export suffix if the path
  doesn't already have one of the format's known suffixes. On some Linux
  native/portal dialogs the extension isn't auto-appended when the user
  doesn't type one, which previously left exportScores() unable to find a
  writer for the path, causing the export to silently fail.

A companion fix in muse_framework (musescore/muse_framework#139) makes the
underlying file dialog request a default suffix directly, which addresses
the same root cause at the source for the single-format case; this commit
adds a safety net that's independent of dialog backend.

Resolves: #33341
Resolves: #33559
---
 src/app/main.cpp                               |  6 +++++-
 src/project/internal/exportprojectscenario.cpp | 14 ++++++++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/src/app/main.cpp b/src/app/main.cpp
index 32651d643063d..5b767c32c83f3 100644
--- a/src/app/main.cpp
+++ b/src/app/main.cpp
@@ -100,7 +100,11 @@ int main(int argc, char** argv)
     }
 
 #ifdef Q_OS_LINUX
-    if (qEnvironmentVariable("MU_QT_QPA_PLATFORM") != "offscreen") {
+    // NOTE: gtk3 is forced by default because it fixed keyboard input in file dialogs (#13113).
+    // Respect an explicitly configured theme (e.g. "xdgdesktopportal") instead of overriding it,
+    // so desktop environments that rely on the portal for native/sandboxed dialogs keep working.
+    if (qEnvironmentVariable("MU_QT_QPA_PLATFORM") != "offscreen"
+        && !qEnvironmentVariableIsSet("QT_QPA_PLATFORMTHEME")) {
         qputenv("QT_QPA_PLATFORMTHEME", "gtk3");
     }
 
diff --git a/src/project/internal/exportprojectscenario.cpp b/src/project/internal/exportprojectscenario.cpp
index 74fcc4c0253a7..2d64b098c480a 100644
--- a/src/project/internal/exportprojectscenario.cpp
+++ b/src/project/internal/exportprojectscenario.cpp
@@ -99,6 +99,20 @@ RetVal<muse::io::path_t> ExportProjectScenario::askExportPath(const INotationPtr
     RetVal<muse::io::path_t> exportPath;
     exportPath.val = interactive()->selectSavingFileSync(muse::trc("project/export", "Export"), defaultPath,
                                                          exportType.filter(), isCreatingOnlyOneFile);
+
+    if (!exportPath.val.empty()) {
+        // Some Linux file dialogs don't auto-append the extension the user didn't type,
+        // which would otherwise leave us without a writer for this path in exportScores().
+        std::string actualSuffix = io::suffix(exportPath.val);
+        bool hasKnownSuffix = std::find_if(exportType.suffixes.cbegin(), exportType.suffixes.cend(), [&actualSuffix](const QString& s) {
+            return s.toStdString() == actualSuffix;
+        }) != exportType.suffixes.cend();
+
+        if (!hasKnownSuffix) {
+            exportPath.val = exportPath.val.appendingSuffix(exportType.suffixes.front().toStdString());
+        }
+    }
+
     exportPath.ret = !exportPath.val.empty();
 
     return exportPath;