From 16f031df4d83bd4e096e7db82f638d8c08e43318 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sat, 29 Nov 2025 21:57:01 -0500
Subject: [PATCH] After further diagnosis, work around Qt6 GL crash.

---
 OSBindings/Qt/clksignal.pro                 |  5 ++---
 Outputs/OpenGL/Primitives/Shader.cpp        | 19 +++++++++++++++++--
 Outputs/OpenGL/Primitives/TextureTarget.cpp |  4 +---
 3 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/OSBindings/Qt/clksignal.pro b/OSBindings/Qt/clksignal.pro
index d1837f1bc..a73103c92 100644
--- a/OSBindings/Qt/clksignal.pro
+++ b/OSBindings/Qt/clksignal.pro
@@ -1,7 +1,6 @@
-QT += core gui multimedia widgets
-greaterThan(5, QT_MAJOR_VERSION) QT += openglwidgets
+QT += core gui multimedia widgets openglwidgets
 
-# Be specific about C++17 but also try the vaguer C++1z for older
+# Be specific about C++20 but also try the vaguer C++2a for older
 # versions of Qt.
 CONFIG += c++20
 CONFIG += c++2a
diff --git a/Outputs/OpenGL/Primitives/Shader.cpp b/Outputs/OpenGL/Primitives/Shader.cpp
index ee862c338..7d34d1ed8 100644
--- a/Outputs/OpenGL/Primitives/Shader.cpp
+++ b/Outputs/OpenGL/Primitives/Shader.cpp
@@ -14,7 +14,9 @@
 using namespace Outputs::Display::OpenGL;
 
 namespace {
+#ifndef TARGET_QT
 thread_local const Shader *bound_shader = nullptr;
+#endif
 using Logger = Log::Logger<Log::Source::OpenGL>;
 }
 
@@ -106,20 +108,30 @@ void Shader::init(const std::string &vertex_shader, const std::string &fragment_
 }
 
 Shader::~Shader() {
+#ifndef TARGET_QT
 	if(bound_shader == this) Shader::unbind();
+#endif
 	glDeleteProgram(shader_program_);
 }
 
 void Shader::bind() const {
+#ifndef TARGET_QT
+	// Qt workaround: it's doing something to interfere with the currently-bound program.
+	// So assume that the driver has a check similar to the below.
 	if(bound_shader != this) {
 		test_gl(glUseProgram, shader_program_);
 		bound_shader = this;
 	}
+#else
+	test_gl(glUseProgram, shader_program_);
+#endif
 	flush_functions();
 }
 
 void Shader::unbind() {
+#ifndef TARGET_QT
 	bound_shader = nullptr;
+#endif
 	test_gl(glUseProgram, 0);
 }
 
@@ -128,7 +140,9 @@ GLint Shader::get_attrib_location(const std::string &name) const {
 }
 
 GLint Shader::get_uniform_location(const std::string &name) const {
-	return glGetUniformLocation(shader_program_, name.c_str());
+	const auto location = glGetUniformLocation(shader_program_, name.c_str());
+	test_gl_error();
+	return location;
 }
 
 void Shader::enable_vertex_attribute_with_pointer(const std::string &name, GLint size, GLenum type, GLboolean normalised, GLsizei stride, const GLvoid *pointer, GLuint divisor) {
@@ -293,8 +307,9 @@ void Shader::enqueue_function(std::function<void(void)> function) {
 
 void Shader::flush_functions() const {
 	std::lock_guard function_guard(function_mutex_);
-	for(std::function<void(void)> function : enqueued_functions_) {
+	for(std::function<void(void)> &function : enqueued_functions_) {
 		function();
+		test_gl_error();
 	}
 	enqueued_functions_.clear();
 }
diff --git a/Outputs/OpenGL/Primitives/TextureTarget.cpp b/Outputs/OpenGL/Primitives/TextureTarget.cpp
index a65b791a3..ff19971fc 100644
--- a/Outputs/OpenGL/Primitives/TextureTarget.cpp
+++ b/Outputs/OpenGL/Primitives/TextureTarget.cpp
@@ -8,8 +8,6 @@
 
 #include "TextureTarget.hpp"
 
-#include <cstdlib>
-#include <vector>
 #include <stdexcept>
 
 using namespace Outputs::Display::OpenGL;
@@ -93,7 +91,7 @@ void TextureTarget::bind_texture() const {
 	test_gl(glBindTexture, GL_TEXTURE_2D, texture_);
 }
 
-void TextureTarget::draw(float aspect_ratio, float colour_threshold) const {
+void TextureTarget::draw(const float aspect_ratio, const float colour_threshold) const {
 	if(!pixel_shader_) {
 		const char *vertex_shader =
 			"#version 150\n"