Don't resolve GLSL extensions if no shaders

If the GL server is 1.x, but the client is 2.x, then the
qt_resolve_glsl_extensions() function was returning true
because the functions existed client-side, when it should
have returned false because the functionality didn't exist
server-side.

Task-number: QTBUG-12478
Reviewed-by: Sarah Smith

1 files changed, 4 insertions, 0 deletions

diff --git a/src/opengl/qglextensions.cpp b/src/opengl/qglextensions.cpp
index c091191..433ccae 100644
--- a/src/opengl/qglextensions.cpp
+++ b/src/opengl/qglextensions.cpp
@@ -233,6 +233,10 @@ bool qt_resolve_glsl_extensions(QGLContext *ctx)
     if (glCreateShader)
         return true;
 
+    // Must at least have the FragmentShader extension to continue.
+    if (!(QGLExtensions::glExtensions() & QGLExtensions::FragmentShader))
+        return false;
+
     glCreateShader = (_glCreateShader) ctx->getProcAddress(QLatin1String("glCreateShader"));
     if (glCreateShader) {
         glShaderSource = (_glShaderSource) ctx->getProcAddress(QLatin1String("glShaderSource"));