From 6fb86c089e54973fed8a8aaf18886625288830b5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Camilla=20L=C3=B6wy?= <elmindreda@elmindreda.org>
Date: Fri, 26 Aug 2022 18:16:29 +0200
Subject: [PATCH] EGL: Add better errors for client API mismatch

Because EGL ties client API support to configs, attempts to create
a context with an unavailable client API will fail with the unhelpful
"failed to find suitable config" error description.

This attempts to detect cases where there are usable configs for the
other client API and emit a hopefully more helpful error.

Related to #2173

(cherry picked from commit e0576666426ff321414f54aefc7583cf457865fc)
---
 src/egl_context.c | 69 ++++++++++++++++++++++++++++++-----------------
 1 file changed, 44 insertions(+), 25 deletions(-)

diff --git a/src/egl_context.c b/src/egl_context.c
index 00f43b5d..7b56acab 100644
--- a/src/egl_context.c
+++ b/src/egl_context.c
@@ -94,7 +94,18 @@ static GLFWbool chooseEGLConfig(const _GLFWctxconfig* ctxconfig,
     EGLConfig* nativeConfigs;
     _GLFWfbconfig* usableConfigs;
     const _GLFWfbconfig* closest;
-    int i, nativeCount, usableCount;
+    int i, nativeCount, usableCount, apiBit;
+    GLFWbool wrongApiAvailable = GLFW_FALSE;
+
+    if (ctxconfig->client == GLFW_OPENGL_ES_API)
+    {
+        if (ctxconfig->major == 1)
+            apiBit = EGL_OPENGL_ES_BIT;
+        else
+            apiBit = EGL_OPENGL_ES2_BIT;
+    }
+    else
+        apiBit = EGL_OPENGL_BIT;
 
     eglGetConfigs(_glfw.egl.display, NULL, 0, &nativeCount);
     if (!nativeCount)
@@ -145,23 +156,10 @@ static GLFWbool chooseEGLConfig(const _GLFWctxconfig* ctxconfig,
         }
 #endif // _GLFW_X11
 
-        if (ctxconfig->client == GLFW_OPENGL_ES_API)
+        if (!(getEGLConfigAttrib(n, EGL_RENDERABLE_TYPE) & apiBit))
         {
-            if (ctxconfig->major == 1)
-            {
-                if (!(getEGLConfigAttrib(n, EGL_RENDERABLE_TYPE) & EGL_OPENGL_ES_BIT))
-                    continue;
-            }
-            else
-            {
-                if (!(getEGLConfigAttrib(n, EGL_RENDERABLE_TYPE) & EGL_OPENGL_ES2_BIT))
-                    continue;
-            }
-        }
-        else if (ctxconfig->client == GLFW_OPENGL_API)
-        {
-            if (!(getEGLConfigAttrib(n, EGL_RENDERABLE_TYPE) & EGL_OPENGL_BIT))
-                continue;
+            wrongApiAvailable = GLFW_TRUE;
+            continue;
         }
 
         u->redBits = getEGLConfigAttrib(n, EGL_RED_SIZE);
@@ -194,6 +192,35 @@ static GLFWbool chooseEGLConfig(const _GLFWctxconfig* ctxconfig,
     closest = _glfwChooseFBConfig(desired, usableConfigs, usableCount);
     if (closest)
         *result = (EGLConfig) closest->handle;
+    else
+    {
+        if (wrongApiAvailable)
+        {
+            if (ctxconfig->client == GLFW_OPENGL_ES_API)
+            {
+                if (ctxconfig->major == 1)
+                {
+                    _glfwInputError(GLFW_API_UNAVAILABLE,
+                                    "EGL: Failed to find support for OpenGL ES 1.x");
+                }
+                else
+                {
+                    _glfwInputError(GLFW_API_UNAVAILABLE,
+                                    "EGL: Failed to find support for OpenGL ES 2 or later");
+                }
+            }
+            else
+            {
+                _glfwInputError(GLFW_API_UNAVAILABLE,
+                                "EGL: Failed to find support for OpenGL");
+            }
+        }
+        else
+        {
+            _glfwInputError(GLFW_FORMAT_UNAVAILABLE,
+                            "EGL: Failed to find a suitable EGLConfig");
+        }
+    }
 
     free(nativeConfigs);
     free(usableConfigs);
@@ -497,11 +524,7 @@ GLFWbool _glfwCreateContextEGL(_GLFWwindow* window,
         share = ctxconfig->share->context.egl.handle;
 
     if (!chooseEGLConfig(ctxconfig, fbconfig, &config))
-    {
-        _glfwInputError(GLFW_FORMAT_UNAVAILABLE,
-                        "EGL: Failed to find a suitable EGLConfig");
         return GLFW_FALSE;
-    }
 
     if (ctxconfig->client == GLFW_OPENGL_ES_API)
     {
@@ -753,11 +776,7 @@ GLFWbool _glfwChooseVisualEGL(const _GLFWwndconfig* wndconfig,
     const long vimask = VisualScreenMask | VisualIDMask;
 
     if (!chooseEGLConfig(ctxconfig, fbconfig, &native))
-    {
-        _glfwInputError(GLFW_FORMAT_UNAVAILABLE,
-                        "EGL: Failed to find a suitable EGLConfig");
         return GLFW_FALSE;
-    }
 
     eglGetConfigAttrib(_glfw.egl.display, native,
                        EGL_NATIVE_VISUAL_ID, &visualID);