From e39c2552ac8521328caa77df20cf39a1bf14e0d4 Mon Sep 17 00:00:00 2001
From: ocornut <omarcornut@gmail.com>
Date: Tue, 14 Mar 2023 15:56:38 +0100
Subject: [PATCH] Backends: GLFW: Avoid using glfwGetError() and
 glfwGetGamepadState() on Emscripten. (#6240)

---
 backends/imgui_impl_glfw.cpp           | 8 +++++---
 docs/CHANGELOG.txt                     | 4 +++-
 examples/example_apple_opengl2/main.mm | 1 +
 3 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/backends/imgui_impl_glfw.cpp b/backends/imgui_impl_glfw.cpp
index f0e70a6dc..29d502b0f 100644
--- a/backends/imgui_impl_glfw.cpp
+++ b/backends/imgui_impl_glfw.cpp
@@ -16,6 +16,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2023-03-14: Emscripten: Avoid using glfwGetError() and glfwGetGamepadState() which are not correctly implemented in Emscripten emulation. (#6240)
 //  2023-02-03: Emscripten: Registering custom low-level mouse wheel handler to get more accurate scrolling impulses on Emscripten. (#4019, #6096)
 //  2023-01-04: Inputs: Fixed mods state on Linux when using Alt-GR text input (e.g. German keyboard layout), could lead to broken text input. Revert a 2022/01/17 change were we resumed using mods provided by GLFW, turns out they were faulty.
 //  2022-11-22: Perform a dummy glfwGetError() read to cancel missing names with glfwGetKeyName(). (#5908)
@@ -95,6 +96,7 @@
 #endif
 #define GLFW_HAS_GAMEPAD_API            (GLFW_VERSION_COMBINED >= 3300) // 3.3+ glfwGetGamepadState() new api
 #define GLFW_HAS_GETKEYNAME             (GLFW_VERSION_COMBINED >= 3200) // 3.2+ glfwGetKeyName()
+#define GLFW_HAS_GETERROR               (GLFW_VERSION_COMBINED >= 3300) // 3.3+ glfwGetError()
 
 // GLFW data
 enum GlfwClientApi
@@ -323,7 +325,7 @@ static int ImGui_ImplGlfw_TranslateUntranslatedKey(int key, int scancode)
     GLFWerrorfun prev_error_callback = glfwSetErrorCallback(nullptr);
     const char* key_name = glfwGetKeyName(key, scancode);
     glfwSetErrorCallback(prev_error_callback);
-#if (GLFW_VERSION_COMBINED >= 3300) // Eat errors (see #5908)
+#if GLFW_HAS_GETERROR && !defined(__EMSCRIPTEN__) // Eat errors (see #5908)
     (void)glfwGetError(NULL);
 #endif
     if (key_name && key_name[0] != 0 && key_name[1] == 0)
@@ -536,7 +538,7 @@ static bool ImGui_ImplGlfw_Init(GLFWwindow* window, bool install_callbacks, Glfw
     bd->MouseCursors[ImGuiMouseCursor_NotAllowed] = glfwCreateStandardCursor(GLFW_ARROW_CURSOR);
 #endif
     glfwSetErrorCallback(prev_error_callback);
-#if (GLFW_VERSION_COMBINED >= 3300) // Eat errors (see #5785)
+#if GLFW_HAS_GETERROR && !defined(__EMSCRIPTEN__) // Eat errors (see #5908)
     (void)glfwGetError(NULL);
 #endif
 
@@ -669,7 +671,7 @@ static void ImGui_ImplGlfw_UpdateGamepads()
         return;
 
     io.BackendFlags &= ~ImGuiBackendFlags_HasGamepad;
-#if GLFW_HAS_GAMEPAD_API
+#if GLFW_HAS_GAMEPAD_API && !defined(__EMSCRIPTEN__)
     GLFWgamepadstate gamepad;
     if (!glfwGetGamepadState(GLFW_JOYSTICK_1, &gamepad))
         return;
diff --git a/docs/CHANGELOG.txt b/docs/CHANGELOG.txt
index a974e47e2..24e369d58 100644
--- a/docs/CHANGELOG.txt
+++ b/docs/CHANGELOG.txt
@@ -87,8 +87,10 @@ Other changes:
   program was pending deletion, attempting to restore it would error. (#6220, #6224) [@Cyphall]
 - Backends: Win32: Use WM_NCMOUSEMOVE / WM_NCMOUSELEAVE to track mouse positions over
   non-client area (e.g. OS decorations) when app is not focused. (#6045, #6162)
-- Backends: SDL2, SDL3:  Accept SDL_GetPerformanceCounter() not returning a monotonically
+- Backends: SDL2, SDL3: Accept SDL_GetPerformanceCounter() not returning a monotonically
   increasing value. (#6189, #6114, #3644) [@adamkewley]
+- Backends: GLFW: Avoid using glfwGetError() and glfwGetGamepadState() on Emscripten, which
+  recently updated its GLFW emulation layer to GLFW 3.3 without supporting those. (#6240)
 - Examples: Android: Fixed example build for Gradle 8. (#6229, #6227) [@duddel]
 - Examples: Updated all examples application to enable ImGuiConfigFlags_NavEnableKeyboard
   and ImGuiConfigFlags_NavEnableGamepad by default. (#787)
diff --git a/examples/example_apple_opengl2/main.mm b/examples/example_apple_opengl2/main.mm
index 11b5bf409..38739ff63 100644
--- a/examples/example_apple_opengl2/main.mm
+++ b/examples/example_apple_opengl2/main.mm
@@ -72,6 +72,7 @@
 -(void)updateAndDrawDemoView
 {
     // Start the Dear ImGui frame
+    ImGuiIO& io = ImGui::GetIO();
     ImGui_ImplOpenGL2_NewFrame();
     ImGui_ImplOSX_NewFrame(self);
     ImGui::NewFrame();