From: Steinar H. Gunderson <sgunderson@bigfoot.com>
Date: Sat, 25 May 2019 15:36:33 +0000 (+0200)
Subject: Work around a Mesa shader cache issue.
X-Git-Tag: 1.9.0~36
X-Git-Url: https://git.sesse.net/?p=nageru;a=commitdiff_plain;h=26da0ebb049dc4c97c2dfda0f35c3546afb5b2a7

Work around a Mesa shader cache issue.
---

diff --git a/shared/context.cpp b/shared/context.cpp
index 6784571..db4babb 100644
--- a/shared/context.cpp
+++ b/shared/context.cpp
@@ -50,7 +50,20 @@ QOpenGLContext *create_context(const QSurface *surface)
 {
 	QOpenGLContext *context = new QOpenGLContext;
 	context->setShareContext(global_share_widget->context()->contextHandle());
-	context->setFormat(surface->format());
+
+	// Qt has a bug (QTBUG-76299) where, when using EGL, the surface ignores
+	// the requested OpenGL context version and just becomes 2.0. Mesa honors
+	// this and gives us a 3.0 compatibility context, but then has a bug related
+	// to its shader cache (Mesa bug #110872) that causes spurious linker failures
+	// when we need to re-link a Movit shader in the same context. However,
+	// the surface itself doesn't use the OpenGL version in its format for anything,
+	// so we can just override it and get a proper context.
+	QSurfaceFormat fmt = surface->format();
+	fmt.setProfile(QSurfaceFormat::CoreProfile);
+	fmt.setMajorVersion(4);
+	fmt.setMinorVersion(5);
+	context->setFormat(fmt);
+
 	context->create();
 	return context;
 }