From 71782da245b16d7566e7818ab8b41d8a1f9057ff Mon Sep 17 00:00:00 2001
From: Ivan Malison <IvanMalison@gmail.com>
Date: Sun, 6 Aug 2023 17:51:18 -0600
Subject: [PATCH 01/17] Add nix flake

---
 flake.lock | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 flake.nix  | 34 +++++++++++++++++++++++
 2 files changed, 114 insertions(+)
 create mode 100644 flake.lock
 create mode 100644 flake.nix

diff --git a/flake.lock b/flake.lock
new file mode 100644
index 0000000000..6afc8e3eb4
--- /dev/null
+++ b/flake.lock
@@ -0,0 +1,80 @@
+{
+  "nodes": {
+    "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1689068808,
+        "narHash": "sha256-6ixXo3wt24N/melDWjq70UuHQLxGV8jZvooRanIHXw0=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "919d646de7be200f3bf08cb76ae1f09402b6f9b4",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "git-ignore-nix": {
+      "inputs": {
+        "nixpkgs": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1660459072,
+        "narHash": "sha256-8DFJjXG8zqoONA1vXtgeKXy68KdJL5UaXR8NtVMUbx8=",
+        "owner": "hercules-ci",
+        "repo": "gitignore.nix",
+        "rev": "a20de23b925fd8264fd7fad6454652e142fd7f73",
+        "type": "github"
+      },
+      "original": {
+        "owner": "hercules-ci",
+        "ref": "master",
+        "repo": "gitignore.nix",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1691186842,
+        "narHash": "sha256-wxBVCvZUwq+XS4N4t9NqsHV4E64cPVqQ2fdDISpjcw0=",
+        "path": "/nix/store/d42v5grfq77vr10r336kks0qjp0wij8d-source",
+        "rev": "18036c0be90f4e308ae3ebcab0e14aae0336fe42",
+        "type": "path"
+      },
+      "original": {
+        "id": "nixpkgs",
+        "type": "indirect"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "git-ignore-nix": "git-ignore-nix",
+        "nixpkgs": "nixpkgs"
+      }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}
diff --git a/flake.nix b/flake.nix
new file mode 100644
index 0000000000..76c0db06c1
--- /dev/null
+++ b/flake.nix
@@ -0,0 +1,34 @@
+{
+  inputs = {
+    flake-utils.url = github:numtide/flake-utils;
+    git-ignore-nix = {
+      url = github:hercules-ci/gitignore.nix/master;
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+  };
+  outputs = {
+    self, flake-utils, nixpkgs, git-ignore-nix, ...
+  }: flake-utils.lib.eachDefaultSystem (system: let
+    overlay = self: super: {
+      picom = super.picom.overrideAttrs (oldAttrs: rec {
+        pname = "picom";
+        buildInputs = [
+          self.pcre2 self.xorg.xcbutil
+        ] ++ self.lib.remove self.xorg.libXinerama (
+          self.lib.remove self.pcre oldAttrs.buildInputs
+        );
+        src = git-ignore-nix.lib.gitignoreSource ./.;
+      });
+    };
+    pkgs = import nixpkgs { inherit system overlays; config.allowBroken = true; };
+    overlays = [ overlay ];
+  in rec {
+    inherit overlay overlays;
+    defaultPackage = pkgs.picom;
+    devShell = defaultPackage.overrideAttrs {
+      buildInputs = defaultPackage.buildInputs ++ [
+        pkgs.clang-tools
+      ];
+    };
+  });
+}

From 249f6818577287ccaf026b3b17da36c8a1331f24 Mon Sep 17 00:00:00 2001
From: Maxim Solovyov <msolovyov@protonmail.com>
Date: Thu, 3 Aug 2023 00:48:57 +0300
Subject: [PATCH 02/17] backend: make target window a parameter of the init
 backend operation

to address a todo
---
 src/backend/backend.h         | 6 +-----
 src/backend/dummy/dummy.c     | 3 ++-
 src/backend/gl/egl.c          | 4 ++--
 src/backend/gl/glx.c          | 4 ++--
 src/backend/xrender/xrender.c | 4 ++--
 src/diagnostic.c              | 2 +-
 src/picom.c                   | 3 ++-
 7 files changed, 12 insertions(+), 14 deletions(-)

diff --git a/src/backend/backend.h b/src/backend/backend.h
index 3ed7a761a8..fd3212f1f6 100644
--- a/src/backend/backend.h
+++ b/src/backend/backend.h
@@ -119,11 +119,7 @@ struct backend_operations {
 	// ===========    Initialization    ===========
 
 	/// Initialize the backend, prepare for rendering to the target window.
-	/// Here is how you should choose target window:
-	///    1) if ps->overlay is not XCB_NONE, use that
-	///    2) use ps->root otherwise
-	// TODO(yshui) make the target window a parameter
-	backend_t *(*init)(session_t *)attr_nonnull(1);
+	backend_t *(*init)(session_t *, xcb_window_t)attr_nonnull(1);
 	void (*deinit)(backend_t *backend_data) attr_nonnull(1);
 
 	/// Called when rendering will be stopped for an unknown amount of
diff --git a/src/backend/dummy/dummy.c b/src/backend/dummy/dummy.c
index 4e3d713873..5e6f13cf9f 100644
--- a/src/backend/dummy/dummy.c
+++ b/src/backend/dummy/dummy.c
@@ -28,7 +28,8 @@ struct dummy_data {
 	struct backend_image mask;
 };
 
-struct backend_base *dummy_init(struct session *ps attr_unused) {
+struct backend_base *
+dummy_init(struct session *ps attr_unused, xcb_window_t target attr_unused) {
 	auto ret = (struct backend_base *)ccalloc(1, struct dummy_data);
 	ret->c = &ps->c;
 	ret->loop = ps->loop;
diff --git a/src/backend/gl/egl.c b/src/backend/gl/egl.c
index a78c1903da..1156dd5922 100644
--- a/src/backend/gl/egl.c
+++ b/src/backend/gl/egl.c
@@ -130,7 +130,7 @@ static bool egl_set_swap_interval(int interval, EGLDisplay dpy) {
 /**
  * Initialize OpenGL.
  */
-static backend_t *egl_init(session_t *ps) {
+static backend_t *egl_init(session_t *ps, xcb_window_t target) {
 	bool success = false;
 	struct egl_data *gd = NULL;
 
@@ -212,7 +212,7 @@ static backend_t *egl_init(session_t *ps) {
 	// clang-format on
 
 	gd->target_win = eglCreatePlatformWindowSurfaceProc(
-	    gd->display, config, (xcb_window_t[]){session_get_target_window(ps)}, NULL);
+	    gd->display, config, (xcb_window_t[]){target}, NULL);
 	if (gd->target_win == EGL_NO_SURFACE) {
 		log_error("Failed to create EGL surface.");
 		goto end;
diff --git a/src/backend/gl/glx.c b/src/backend/gl/glx.c
index 681bd17470..cb55d4d9b0 100644
--- a/src/backend/gl/glx.c
+++ b/src/backend/gl/glx.c
@@ -227,13 +227,13 @@ static bool glx_set_swap_interval(int interval, Display *dpy, GLXDrawable drawab
 /**
  * Initialize OpenGL.
  */
-static backend_t *glx_init(session_t *ps) {
+static backend_t *glx_init(session_t *ps, xcb_window_t target) {
 	bool success = false;
 	glxext_init(ps->c.dpy, ps->c.screen);
 	auto gd = ccalloc(1, struct _glx_data);
 	init_backend_base(&gd->gl.base, ps);
 
-	gd->target_win = session_get_target_window(ps);
+	gd->target_win = target;
 
 	XVisualInfo *pvis = NULL;
 
diff --git a/src/backend/xrender/xrender.c b/src/backend/xrender/xrender.c
index c359fc4efa..b175ceaf21 100644
--- a/src/backend/xrender/xrender.c
+++ b/src/backend/xrender/xrender.c
@@ -869,7 +869,7 @@ static void get_blur_size(void *blur_context, int *width, int *height) {
 	*height = ctx->resize_height;
 }
 
-static backend_t *backend_xrender_init(session_t *ps) {
+static backend_t *backend_xrender_init(session_t *ps, xcb_window_t target) {
 	if (ps->o.dithered_present) {
 		log_warn("\"dithered-present\" is not supported by the xrender backend.");
 	}
@@ -888,7 +888,7 @@ static backend_t *backend_xrender_init(session_t *ps) {
 	xd->black_pixel = solid_picture(&ps->c, true, 1, 0, 0, 0);
 	xd->white_pixel = solid_picture(&ps->c, true, 1, 1, 1, 1);
 
-	xd->target_win = session_get_target_window(ps);
+	xd->target_win = target;
 	xcb_render_create_picture_value_list_t pa = {
 	    .subwindowmode = XCB_SUBWINDOW_MODE_INCLUDE_INFERIORS,
 	};
diff --git a/src/diagnostic.c b/src/diagnostic.c
index 1159d9eabc..ce93cfc0c2 100644
--- a/src/diagnostic.c
+++ b/src/diagnostic.c
@@ -39,7 +39,7 @@ void print_diagnostics(session_t *ps, const char *config_file, bool compositor_r
 	for (int i = 0; i < NUM_BKEND; i++) {
 		if (backend_list[i] && backend_list[i]->diagnostics) {
 			printf("\n### Backend: %s\n\n", BACKEND_STRS[i]);
-			auto data = backend_list[i]->init(ps);
+			auto data = backend_list[i]->init(ps, session_get_target_window(ps));
 			if (!data) {
 				printf(" Cannot initialize this backend\n");
 			} else {
diff --git a/src/picom.c b/src/picom.c
index bf18523f9f..c9772e3b17 100644
--- a/src/picom.c
+++ b/src/picom.c
@@ -605,7 +605,8 @@ static bool initialize_backend(session_t *ps) {
 		assert(!ps->backend_data);
 		// Reinitialize win_data
 		assert(backend_list[ps->o.backend]);
-		ps->backend_data = backend_list[ps->o.backend]->init(ps);
+		ps->backend_data =
+		    backend_list[ps->o.backend]->init(ps, session_get_target_window(ps));
 		if (!ps->backend_data) {
 			log_fatal("Failed to initialize backend, aborting...");
 			quit(ps);

From 825cc563e18a4823285615336a250484d56d9473 Mon Sep 17 00:00:00 2001
From: Maxim Solovyov <msolovyov@protonmail.com>
Date: Thu, 3 Aug 2023 00:53:44 +0300
Subject: [PATCH 03/17] backend: egl: simplify usage of the target window
 parameter in egl_init

---
 src/backend/gl/egl.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/backend/gl/egl.c b/src/backend/gl/egl.c
index 1156dd5922..ca70359173 100644
--- a/src/backend/gl/egl.c
+++ b/src/backend/gl/egl.c
@@ -211,8 +211,8 @@ static backend_t *egl_init(session_t *ps, xcb_window_t target) {
 	}
 	// clang-format on
 
-	gd->target_win = eglCreatePlatformWindowSurfaceProc(
-	    gd->display, config, (xcb_window_t[]){target}, NULL);
+	gd->target_win =
+	    eglCreatePlatformWindowSurfaceProc(gd->display, config, &target, NULL);
 	if (gd->target_win == EGL_NO_SURFACE) {
 		log_error("Failed to create EGL surface.");
 		goto end;

From 156423c0104fbac7f3eb7c50c0fa4812345968fc Mon Sep 17 00:00:00 2001
From: Maxim Solovyov <msolovyov@protonmail.com>
Date: Thu, 3 Aug 2023 01:04:56 +0300
Subject: [PATCH 04/17] backend: dummy: change type of ps parameter to
 session_t in dummy_init

---
 src/backend/dummy/dummy.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/dummy/dummy.c b/src/backend/dummy/dummy.c
index 5e6f13cf9f..f4fa5f459f 100644
--- a/src/backend/dummy/dummy.c
+++ b/src/backend/dummy/dummy.c
@@ -28,8 +28,7 @@ struct dummy_data {
 	struct backend_image mask;
 };
 
-struct backend_base *
-dummy_init(struct session *ps attr_unused, xcb_window_t target attr_unused) {
+struct backend_base *dummy_init(session_t *ps attr_unused, xcb_window_t target attr_unused) {
 	auto ret = (struct backend_base *)ccalloc(1, struct dummy_data);
 	ret->c = &ps->c;
 	ret->loop = ps->loop;

From 8bf82857c4542877b4e2fa36761acb70f6fa2e2d Mon Sep 17 00:00:00 2001
From: Maxim Solovyov <msolovyov@protonmail.com>
Date: Thu, 3 Aug 2023 01:38:34 +0300
Subject: [PATCH 05/17] backend: name default backend operation implementations
 consistently

---
 src/backend/backend.h         | 6 +++---
 src/backend/backend_common.c  | 4 ++--
 src/backend/backend_common.h  | 4 ++--
 src/backend/dummy/dummy.c     | 2 +-
 src/backend/xrender/xrender.c | 2 +-
 5 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/src/backend/backend.h b/src/backend/backend.h
index 3ed7a761a8..6a05a55090 100644
--- a/src/backend/backend.h
+++ b/src/backend/backend.h
@@ -215,18 +215,18 @@ struct backend_operations {
 	                     struct xvisual_info fmt, bool owned);
 
 	/// Create a shadow context for rendering shadows with radius `radius`.
-	/// Default implementation: default_backend_create_shadow_context
+	/// Default implementation: default_create_shadow_context
 	struct backend_shadow_context *(*create_shadow_context)(backend_t *backend_data,
 	                                                        double radius);
 	/// Destroy a shadow context
-	/// Default implementation: default_backend_destroy_shadow_context
+	/// Default implementation: default_destroy_shadow_context
 	void (*destroy_shadow_context)(backend_t *backend_data,
 	                               struct backend_shadow_context *ctx);
 
 	/// Create a shadow image based on the parameters. Resulting image should have a
 	/// size of `width + radisu * 2` x `height + radius * 2`. Radius is set when the
 	/// shadow context is created.
-	/// Default implementation: default_backend_render_shadow
+	/// Default implementation: default_render_shadow
 	///
 	/// Required.
 	void *(*render_shadow)(backend_t *backend_data, int width, int height,
diff --git a/src/backend/backend_common.c b/src/backend/backend_common.c
index 3388b78516..eef214593b 100644
--- a/src/backend/backend_common.c
+++ b/src/backend/backend_common.c
@@ -293,8 +293,8 @@ bool build_shadow(struct x_connection *c, double opacity, const int width,
 	return false;
 }
 
-void *default_backend_render_shadow(backend_t *backend_data, int width, int height,
-                                    struct backend_shadow_context *sctx, struct color color) {
+void *default_render_shadow(backend_t *backend_data, int width, int height,
+                            struct backend_shadow_context *sctx, struct color color) {
 	const conv *kernel = (void *)sctx;
 	xcb_render_picture_t shadow_pixel =
 	    solid_picture(backend_data->c, true, 1, color.red, color.green, color.blue);
diff --git a/src/backend/backend_common.h b/src/backend/backend_common.h
index 2e49cecf71..a58d816c0a 100644
--- a/src/backend/backend_common.h
+++ b/src/backend/backend_common.h
@@ -62,8 +62,8 @@ bool default_is_win_transparent(void *, win *, void *);
 /// caveat as `default_is_win_transparent` applies.
 bool default_is_frame_transparent(void *, win *, void *);
 
-void *default_backend_render_shadow(backend_t *backend_data, int width, int height,
-                                    struct backend_shadow_context *sctx, struct color color);
+void *default_render_shadow(backend_t *backend_data, int width, int height,
+                            struct backend_shadow_context *sctx, struct color color);
 
 /// Implement `render_shadow` with `shadow_from_mask`.
 void *
diff --git a/src/backend/dummy/dummy.c b/src/backend/dummy/dummy.c
index 4e3d713873..19e88ddc85 100644
--- a/src/backend/dummy/dummy.c
+++ b/src/backend/dummy/dummy.c
@@ -184,7 +184,7 @@ struct backend_operations dummy_ops = {
     .bind_pixmap = dummy_bind_pixmap,
     .create_shadow_context = default_create_shadow_context,
     .destroy_shadow_context = default_destroy_shadow_context,
-    .render_shadow = default_backend_render_shadow,
+    .render_shadow = default_render_shadow,
     .make_mask = dummy_make_mask,
     .release_image = dummy_release_image,
     .is_image_transparent = dummy_is_image_transparent,
diff --git a/src/backend/xrender/xrender.c b/src/backend/xrender/xrender.c
index c359fc4efa..5c7d786ef4 100644
--- a/src/backend/xrender/xrender.c
+++ b/src/backend/xrender/xrender.c
@@ -981,7 +981,7 @@ struct backend_operations xrender_ops = {
     .release_image = release_image,
     .create_shadow_context = default_create_shadow_context,
     .destroy_shadow_context = default_destroy_shadow_context,
-    .render_shadow = default_backend_render_shadow,
+    .render_shadow = default_render_shadow,
     .make_mask = make_mask,
     //.prepare_win = prepare_win,
     //.release_win = release_win,

From bd3134efd982397a3c51a48a7d7f13e25b87c41d Mon Sep 17 00:00:00 2001
From: Maxim Solovyov <msolovyov@protonmail.com>
Date: Thu, 3 Aug 2023 01:42:00 +0300
Subject: [PATCH 06/17] backend: xrender: remove obsolete commented out backend
 operations

---
 src/backend/xrender/xrender.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/src/backend/xrender/xrender.c b/src/backend/xrender/xrender.c
index 5c7d786ef4..f7ef8616c1 100644
--- a/src/backend/xrender/xrender.c
+++ b/src/backend/xrender/xrender.c
@@ -983,8 +983,6 @@ struct backend_operations xrender_ops = {
     .destroy_shadow_context = default_destroy_shadow_context,
     .render_shadow = default_render_shadow,
     .make_mask = make_mask,
-    //.prepare_win = prepare_win,
-    //.release_win = release_win,
     .is_image_transparent = default_is_image_transparent,
     .buffer_age = buffer_age,
     .max_buffer_age = 2,

From 44800ed845fad3fb0638891764a3b17084c96c3a Mon Sep 17 00:00:00 2001
From: Maxim Solovyov <msolovyov@protonmail.com>
Date: Thu, 3 Aug 2023 01:44:54 +0300
Subject: [PATCH 07/17] backend: remove default implementations of obsolete
 backend operations

---
 src/backend/backend_common.h | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/src/backend/backend_common.h b/src/backend/backend_common.h
index a58d816c0a..da9ccd0235 100644
--- a/src/backend/backend_common.h
+++ b/src/backend/backend_common.h
@@ -54,14 +54,6 @@ solid_picture(struct x_connection *, bool argb, double a, double r, double g, do
 xcb_image_t *make_shadow(struct x_connection *c, const conv *kernel, double opacity,
                          int width, int height);
 
-/// The default implementation of `is_win_transparent`, it simply looks at win::mode. So
-/// this is not suitable for backends that alter the content of windows
-bool default_is_win_transparent(void *, win *, void *);
-
-/// The default implementation of `is_frame_transparent`, it uses win::frame_opacity. Same
-/// caveat as `default_is_win_transparent` applies.
-bool default_is_frame_transparent(void *, win *, void *);
-
 void *default_render_shadow(backend_t *backend_data, int width, int height,
                             struct backend_shadow_context *sctx, struct color color);
 

From e07b1d7a127950b4633fa5459341ab234e9e5bc6 Mon Sep 17 00:00:00 2001
From: Maxim Solovyov <msolovyov@protonmail.com>
Date: Sun, 10 Sep 2023 22:32:02 +0300
Subject: [PATCH 08/17] backend: gl: convert the shadow color to the
 premultiplied format

to respect the globally set glBlendFunc and thus get the correct and
expected result
---
 src/backend/gl/gl_common.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/backend/gl/gl_common.c b/src/backend/gl/gl_common.c
index d437fdd7bd..786e82f413 100644
--- a/src/backend/gl/gl_common.c
+++ b/src/backend/gl/gl_common.c
@@ -1347,8 +1347,11 @@ void *gl_shadow_from_mask(backend_t *base, void *mask,
 
 	glBindTexture(GL_TEXTURE_2D, tmp_texture);
 	glUseProgram(gd->shadow_shader.prog);
-	glUniform4f(gd->shadow_shader.uniform_color, (GLfloat)color.red,
-	            (GLfloat)color.green, (GLfloat)color.blue, (GLfloat)color.alpha);
+	// The shadow color is converted to the premultiplied format to respect the
+	// globally set glBlendFunc and thus get the correct and expected result.
+	glUniform4f(gd->shadow_shader.uniform_color, (GLfloat)(color.red * color.alpha),
+	            (GLfloat)(color.green * color.alpha),
+	            (GLfloat)(color.blue * color.alpha), (GLfloat)color.alpha);
 
 	// clang-format off
 	GLuint indices[] = {0, 1, 2, 2, 3, 0};

From 47bb825b2c4965d1874d983c7128af0fbfb6b4cb Mon Sep 17 00:00:00 2001
From: Yuxuan Shui <yshuiv7@gmail.com>
Date: Sun, 17 Dec 2023 08:39:02 +0000
Subject: [PATCH 09/17] backend: glx: don't return false from a function
 returning void *

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>
---
 src/backend/gl/glx.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/backend/gl/glx.c b/src/backend/gl/glx.c
index cb55d4d9b0..78143a2b77 100644
--- a/src/backend/gl/glx.c
+++ b/src/backend/gl/glx.c
@@ -371,12 +371,12 @@ glx_bind_pixmap(backend_t *base, xcb_pixmap_t pixmap, struct xvisual_info fmt, b
 	if (fmt.visual_depth > OPENGL_MAX_DEPTH) {
 		log_error("Requested depth %d higher than max possible depth %d.",
 		          fmt.visual_depth, OPENGL_MAX_DEPTH);
-		return false;
+		return NULL;
 	}
 
 	if (fmt.visual_depth < 0) {
 		log_error("Pixmap %#010x with invalid depth %d", pixmap, fmt.visual_depth);
-		return false;
+		return NULL;
 	}
 
 	auto r =

From 1b97f18e5f037d40a59f2dab9a32037b7a735f96 Mon Sep 17 00:00:00 2001
From: Yuxuan Shui <yshuiv7@gmail.com>
Date: Sun, 17 Dec 2023 08:50:47 +0000
Subject: [PATCH 10/17] compiler: bring the unreachable macro in line with C23

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>
---
 src/c2.c       |  2 +-
 src/compiler.h | 10 ++++++----
 src/utils.c    |  2 +-
 src/win.c      |  2 +-
 4 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/src/c2.c b/src/c2.c
index d82448aa24..7f1f80e0f7 100644
--- a/src/c2.c
+++ b/src/c2.c
@@ -1336,7 +1336,7 @@ static xcb_atom_t c2_get_atom_type(const c2_l_t *pleaf) {
 	case C2_L_TDRAWABLE: return XCB_ATOM_DRAWABLE;
 	default: assert(0); break;
 	}
-	unreachable;
+	unreachable();
 }
 
 /**
diff --git a/src/compiler.h b/src/compiler.h
index 76326707b0..af8fb83190 100644
--- a/src/compiler.h
+++ b/src/compiler.h
@@ -101,10 +101,12 @@
 # endif
 #endif
 
-#if defined(__GNUC__) || defined(__clang__)
-# define unreachable __builtin_unreachable()
-#else
-# define unreachable do {} while(0)
+#ifndef unreachable
+# if defined(__GNUC__) || defined(__clang__)
+#  define unreachable() __builtin_unreachable()
+# else
+#  define unreachable() do {} while(0)
+# endif
 #endif
 
 #ifndef __has_include
diff --git a/src/utils.c b/src/utils.c
index d26afa331e..5709fa21d2 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -30,7 +30,7 @@ void report_allocation_failure(const char *func, const char *file, unsigned int
 	ssize_t _ attr_unused = writev(STDERR_FILENO, v, ARR_SIZE(v));
 	abort();
 
-	unreachable;
+	unreachable();
 }
 
 ///
diff --git a/src/win.c b/src/win.c
index bd19b3d412..6dccbed652 100644
--- a/src/win.c
+++ b/src/win.c
@@ -2433,7 +2433,7 @@ bool win_check_fade_finished(session_t *ps, struct managed_win *w) {
 		case WSTATE_DESTROYING: destroy_win_finish(ps, &w->base); return true;
 		case WSTATE_MAPPING: map_win_finish(w); return false;
 		case WSTATE_FADING: w->state = WSTATE_MAPPED; break;
-		default: unreachable;
+		default: unreachable();
 		}
 	}
 

From e92745671baf07cce8044c99451418f1aa29f25a Mon Sep 17 00:00:00 2001
From: Yuxuan Shui <yshuiv7@gmail.com>
Date: Sun, 17 Dec 2023 08:55:23 +0000
Subject: [PATCH 11/17] compiler: use C23 auto when available

One annoying thing is C23 still defines auto as a storage class despite
it now being used for type inference. As a consequence we must write
"auto const" instead of the more natural "const auto".

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>
---
 src/backend/xrender/xrender.c | 20 ++++++++++----------
 src/compiler.h                |  2 ++
 src/picom.c                   |  4 ++--
 src/render.c                  | 20 ++++++++++----------
 src/win.c                     |  6 +++---
 5 files changed, 27 insertions(+), 25 deletions(-)

diff --git a/src/backend/xrender/xrender.c b/src/backend/xrender/xrender.c
index cc6e5f430a..5d04ff272b 100644
--- a/src/backend/xrender/xrender.c
+++ b/src/backend/xrender/xrender.c
@@ -176,8 +176,8 @@ static xcb_render_picture_t process_mask(struct _xrender_data *xd, struct xrende
 		*allocated = false;
 		return inner->pict;
 	}
-	const auto tmpw = to_u16_checked(inner->width);
-	const auto tmph = to_u16_checked(inner->height);
+	auto const tmpw = to_u16_checked(inner->width);
+	auto const tmph = to_u16_checked(inner->height);
 	*allocated = true;
 	x_clear_picture_clip_region(xd->base.c, inner->pict);
 	auto ret = x_create_picture_with_visual(
@@ -226,13 +226,13 @@ compose_impl(struct _xrender_data *xd, struct xrender_image *xrimg, coord_t dst,
 	region_t reg;
 
 	bool has_alpha = inner->has_alpha || img->opacity != 1;
-	const auto tmpw = to_u16_checked(inner->width);
-	const auto tmph = to_u16_checked(inner->height);
-	const auto tmpew = to_u16_checked(img->ewidth);
-	const auto tmpeh = to_u16_checked(img->eheight);
+	auto const tmpw = to_u16_checked(inner->width);
+	auto const tmph = to_u16_checked(inner->height);
+	auto const tmpew = to_u16_checked(img->ewidth);
+	auto const tmpeh = to_u16_checked(img->eheight);
 	// Remember: the mask has a 1-pixel border
-	const auto mask_dst_x = to_i16_checked(dst.x - mask_dst.x + 1);
-	const auto mask_dst_y = to_i16_checked(dst.y - mask_dst.y + 1);
+	auto const mask_dst_x = to_i16_checked(dst.x - mask_dst.x + 1);
+	auto const mask_dst_y = to_i16_checked(dst.y - mask_dst.y + 1);
 	const xcb_render_color_t dim_color = {
 	    .red = 0, .green = 0, .blue = 0, .alpha = (uint16_t)(0xffff * img->dim)};
 
@@ -395,8 +395,8 @@ static bool blur(backend_t *backend_data, double opacity, void *ctx_, void *mask
 	    resize_region(&reg_op, bctx->resize_width, bctx->resize_height);
 
 	const pixman_box32_t *extent_resized = pixman_region32_extents(&reg_op_resized);
-	const auto height_resized = to_u16_checked(extent_resized->y2 - extent_resized->y1);
-	const auto width_resized = to_u16_checked(extent_resized->x2 - extent_resized->x1);
+	auto const height_resized = to_u16_checked(extent_resized->y2 - extent_resized->y1);
+	auto const width_resized = to_u16_checked(extent_resized->x2 - extent_resized->x1);
 	static const char *filter0 = "Nearest";        // The "null" filter
 	static const char *filter = "convolution";
 
diff --git a/src/compiler.h b/src/compiler.h
index af8fb83190..302bc7bbed 100644
--- a/src/compiler.h
+++ b/src/compiler.h
@@ -7,7 +7,9 @@
 #endif
 
 // clang-format off
+#if __STDC_VERSION__ <= 201710L
 #define auto           __auto_type
+#endif
 #define likely(x)      __builtin_expect(!!(x), 1)
 #define unlikely(x)    __builtin_expect(!!(x), 0)
 #define likely_if(x)   if (likely(x))
diff --git a/src/picom.c b/src/picom.c
index c9772e3b17..1302f51465 100644
--- a/src/picom.c
+++ b/src/picom.c
@@ -265,7 +265,7 @@ void schedule_render(session_t *ps, bool triggered_by_vblank) {
 		goto schedule;
 	}
 
-	const auto deadline = ps->last_msc_instant + (unsigned long)divisor * frame_time;
+	auto const deadline = ps->last_msc_instant + (unsigned long)divisor * frame_time;
 	unsigned int available = 0;
 	if (deadline > now_us) {
 		available = (unsigned int)(deadline - now_us);
@@ -1158,7 +1158,7 @@ static int register_cm(session_t *ps) {
 	// Set WM_CLIENT_MACHINE. As per EWMH, because we set _NET_WM_PID, we must also
 	// set WM_CLIENT_MACHINE.
 	{
-		const auto hostname_max = (unsigned long)sysconf(_SC_HOST_NAME_MAX);
+		auto const hostname_max = (unsigned long)sysconf(_SC_HOST_NAME_MAX);
 		char *hostname = malloc(hostname_max);
 
 		if (gethostname(hostname, hostname_max) == 0) {
diff --git a/src/render.c b/src/render.c
index 3a7e844842..ec50d8a3ec 100644
--- a/src/render.c
+++ b/src/render.c
@@ -474,10 +474,10 @@ void paint_one(session_t *ps, struct managed_win *w, const region_t *reg_paint)
 	} else {
 		// Painting parameters
 		const margin_t extents = win_calc_frame_extents(w);
-		const auto t = extents.top;
-		const auto l = extents.left;
-		const auto b = extents.bottom;
-		const auto r = extents.right;
+		auto const t = extents.top;
+		auto const l = extents.left;
+		auto const b = extents.bottom;
+		auto const r = extents.right;
 
 #define COMP_BDR(cx, cy, cwid, chei)                                                     \
 	paint_region(ps, w, (cx), (cy), (cwid), (chei), w->frame_opacity * w->opacity,   \
@@ -888,8 +888,8 @@ win_blur_background(session_t *ps, struct managed_win *w, xcb_render_picture_t t
                     const region_t *reg_paint) {
 	const int16_t x = w->g.x;
 	const int16_t y = w->g.y;
-	const auto wid = to_u16_checked(w->widthb);
-	const auto hei = to_u16_checked(w->heightb);
+	auto const wid = to_u16_checked(w->widthb);
+	auto const hei = to_u16_checked(w->heightb);
 	const int cr = w ? w->corner_radius : 0;
 
 	double factor_center = 1.0;
@@ -1174,8 +1174,8 @@ void paint_all(session_t *ps, struct managed_win *t) {
 			if (w->corner_radius > 0 && ps->o.backend == BKEND_GLX) {
 				const int16_t x = w->g.x;
 				const int16_t y = w->g.y;
-				const auto wid = to_u16_checked(w->widthb);
-				const auto hei = to_u16_checked(w->heightb);
+				auto const wid = to_u16_checked(w->widthb);
+				auto const hei = to_u16_checked(w->heightb);
 				glx_bind_texture(ps, &w->glx_texture_bg, x, y, wid, hei);
 			}
 #endif
@@ -1195,8 +1195,8 @@ void paint_all(session_t *ps, struct managed_win *t) {
 			// Rounded corners for XRender is implemented inside render()
 			// Round window corners
 			if (w->corner_radius > 0 && ps->o.backend == BKEND_GLX) {
-				const auto wid = to_u16_checked(w->widthb);
-				const auto hei = to_u16_checked(w->heightb);
+				auto const wid = to_u16_checked(w->widthb);
+				auto const hei = to_u16_checked(w->heightb);
 				glx_round_corners_dst(ps, w, w->glx_texture_bg, w->g.x,
 				                      w->g.y, wid, hei,
 				                      (float)ps->psglx->z - 0.5F,
diff --git a/src/win.c b/src/win.c
index 6dccbed652..901b646cae 100644
--- a/src/win.c
+++ b/src/win.c
@@ -2758,7 +2758,7 @@ void win_clear_flags(struct managed_win *w, uint64_t flags) {
 }
 
 void win_set_properties_stale(struct managed_win *w, const xcb_atom_t *props, int nprops) {
-	const auto bits_per_element = sizeof(*w->stale_props) * 8;
+	auto const bits_per_element = sizeof(*w->stale_props) * 8;
 	size_t new_capacity = w->stale_props_capacity;
 
 	// Calculate the new capacity of the properties array
@@ -2793,12 +2793,12 @@ static void win_clear_all_properties_stale(struct managed_win *w) {
 }
 
 static bool win_fetch_and_unset_property_stale(struct managed_win *w, xcb_atom_t prop) {
-	const auto bits_per_element = sizeof(*w->stale_props) * 8;
+	auto const bits_per_element = sizeof(*w->stale_props) * 8;
 	if (prop >= w->stale_props_capacity * bits_per_element) {
 		return false;
 	}
 
-	const auto mask = 1UL << (prop % bits_per_element);
+	auto const mask = 1UL << (prop % bits_per_element);
 	bool ret = w->stale_props[prop / bits_per_element] & mask;
 	w->stale_props[prop / bits_per_element] &= ~mask;
 	return ret;

From 268e1d890ab7d982cbcbec034c3ccebd09c8b10b Mon Sep 17 00:00:00 2001
From: Yuxuan Shui <yshuiv7@gmail.com>
Date: Sun, 17 Dec 2023 23:34:34 +0000
Subject: [PATCH 12/17] core: exit if paint_preprocess fails

This usually means there is another compositor running. If we don't do
this picom will spin forever.

Fixes #1104

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>
---
 src/picom.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/picom.c b/src/picom.c
index 1302f51465..fa9182bf12 100644
--- a/src/picom.c
+++ b/src/picom.c
@@ -1741,6 +1741,11 @@ static void draw_callback_impl(EV_P_ session_t *ps, int revents attr_unused) {
 	auto bottom = paint_preprocess(ps, &fade_running, &animation);
 	ps->tmout_unredir_hit = false;
 
+	if (!bottom) {
+		log_fatal("Pre-render preparation has failed, exiting...");
+		exit(1);
+	}
+
 	if (!was_redirected && ps->redirected) {
 		// paint_preprocess redirected the screen, which might change the state of
 		// some of the windows (e.g. the window image might become stale).

From 7366553be2b825495c5b1e09be09d0fabde4b9b4 Mon Sep 17 00:00:00 2001
From: Yuxuan Shui <yshuiv7@gmail.com>
Date: Sun, 17 Dec 2023 23:44:56 +0000
Subject: [PATCH 13/17] core: distinguish preprocess failure and no window to
 render

paint_process would return NULL for both of these cases, but we should exit in
the failure case, and continue going in the other.

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>
---
 src/picom.c | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/src/picom.c b/src/picom.c
index fa9182bf12..6f3c2908d9 100644
--- a/src/picom.c
+++ b/src/picom.c
@@ -769,13 +769,19 @@ static void handle_root_flags(session_t *ps) {
 	}
 }
 
-static struct managed_win *
-paint_preprocess(session_t *ps, bool *fade_running, bool *animation) {
+/**
+ * Go through the window stack and calculate some parameters for rendering.
+ *
+ * @return whether the operation succeeded
+ */
+static bool paint_preprocess(session_t *ps, bool *fade_running, bool *animation,
+                             struct managed_win **out_bottom) {
 	// XXX need better, more general name for `fade_running`. It really
 	// means if fade is still ongoing after the current frame is rendered
 	struct managed_win *bottom = NULL;
 	*fade_running = false;
 	*animation = false;
+	*out_bottom = NULL;
 
 	// Fading step calculation
 	long long steps = 0L;
@@ -1036,12 +1042,13 @@ paint_preprocess(session_t *ps, bool *fade_running, bool *animation) {
 		ev_timer_stop(ps->loop, &ps->unredir_timer);
 		if (!ps->redirected) {
 			if (!redirect_start(ps)) {
-				return NULL;
+				return false;
 			}
 		}
 	}
 
-	return bottom;
+	*out_bottom = bottom;
+	return true;
 }
 
 void root_damaged(session_t *ps) {
@@ -1738,14 +1745,14 @@ static void draw_callback_impl(EV_P_ session_t *ps, int revents attr_unused) {
 	bool fade_running = false;
 	bool animation = false;
 	bool was_redirected = ps->redirected;
-	auto bottom = paint_preprocess(ps, &fade_running, &animation);
-	ps->tmout_unredir_hit = false;
-
-	if (!bottom) {
+	struct managed_win *bottom = NULL;
+	if (!paint_preprocess(ps, &fade_running, &animation, &bottom)) {
 		log_fatal("Pre-render preparation has failed, exiting...");
 		exit(1);
 	}
 
+	ps->tmout_unredir_hit = false;
+
 	if (!was_redirected && ps->redirected) {
 		// paint_preprocess redirected the screen, which might change the state of
 		// some of the windows (e.g. the window image might become stale).

From aed2a205ed30a5c65ad86f98a3bfae4b1ae3bff8 Mon Sep 17 00:00:00 2001
From: Yuxuan Shui <yshuiv7@gmail.com>
Date: Mon, 18 Dec 2023 04:11:18 +0000
Subject: [PATCH 14/17] log: add a new log level, verbose

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>
---
 src/log.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/log.h b/src/log.h
index e40fe3c8f4..6d74126c06 100644
--- a/src/log.h
+++ b/src/log.h
@@ -9,11 +9,19 @@
 
 enum log_level {
 	LOG_LEVEL_INVALID = -1,
+	/// Very noisy debug messages, many lines per frame.
 	LOG_LEVEL_TRACE = 0,
+	/// Frequent debug messages, a few lines per frame.
+	LOG_LEVEL_VERBOSE,
+	/// Less frequent debug messages.
 	LOG_LEVEL_DEBUG,
+	/// Informational messages.
 	LOG_LEVEL_INFO,
+	/// Warnings.
 	LOG_LEVEL_WARN,
+	/// Errors.
 	LOG_LEVEL_ERROR,
+	/// Fatal errors.
 	LOG_LEVEL_FATAL,
 };
 
@@ -31,6 +39,7 @@ enum log_level {
 		}                                                                              \
 	} while (0)
 #define log_trace(x, ...) LOG_UNLIKELY(TRACE, x, ##__VA_ARGS__)
+#define log_verbose(x, ...) LOG_UNLIKELY(VERBOSE, x, ##__VA_ARGS__)
 #define log_debug(x, ...) LOG_UNLIKELY(DEBUG, x, ##__VA_ARGS__)
 #define log_info(x, ...) LOG(INFO, x, ##__VA_ARGS__)
 #define log_warn(x, ...) LOG(WARN, x, ##__VA_ARGS__)

From c7ec4c2c1624cdfd2ad8936e3cdf70023f62459b Mon Sep 17 00:00:00 2001
From: Yuxuan Shui <yshuiv7@gmail.com>
Date: Mon, 18 Dec 2023 04:15:27 +0000
Subject: [PATCH 15/17] log: fix printing and parsing of the verbose log level

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>
---
 src/log.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/log.c b/src/log.c
index 870d755750..99f310a654 100644
--- a/src/log.c
+++ b/src/log.c
@@ -68,6 +68,7 @@ log_default_writev(struct log_target *tgt, const struct iovec *vec, int vcnt) {
 static attr_const const char *log_level_to_string(enum log_level level) {
 	switch (level) {
 	case LOG_LEVEL_TRACE: return "TRACE";
+	case LOG_LEVEL_VERBOSE: return "VERBOSE";
 	case LOG_LEVEL_DEBUG: return "DEBUG";
 	case LOG_LEVEL_INFO: return "INFO";
 	case LOG_LEVEL_WARN: return "WARN";
@@ -81,6 +82,9 @@ enum log_level string_to_log_level(const char *str) {
 	if (strcasecmp(str, "TRACE") == 0) {
 		return LOG_LEVEL_TRACE;
 	}
+	if (strcasecmp(str, "VERBOSE") == 0) {
+		return LOG_LEVEL_VERBOSE;
+	}
 	if (strcasecmp(str, "DEBUG") == 0) {
 		return LOG_LEVEL_DEBUG;
 	}
@@ -234,12 +238,10 @@ struct log_target *null_logger_new(void) {
 
 static void null_logger_write(struct log_target *tgt attr_unused,
                               const char *str attr_unused, size_t len attr_unused) {
-	return;
 }
 
 static void null_logger_writev(struct log_target *tgt attr_unused,
                                const struct iovec *vec attr_unused, int vcnt attr_unused) {
-	return;
 }
 
 static const struct log_ops null_logger_ops = {

From e60cb65672e585ad250a123794185350c0f41f18 Mon Sep 17 00:00:00 2001
From: Yuxuan Shui <yshuiv7@gmail.com>
Date: Mon, 18 Dec 2023 04:18:18 +0000
Subject: [PATCH 16/17] log: give verbose log level a color

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>
---
 src/log.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/log.c b/src/log.c
index 99f310a654..664b9f41be 100644
--- a/src/log.c
+++ b/src/log.c
@@ -277,6 +277,7 @@ static void file_logger_destroy(struct log_target *tgt) {
 static const char *terminal_colorize_begin(enum log_level level) {
 	switch (level) {
 	case LOG_LEVEL_TRACE: return ANSI("30;2");
+	case LOG_LEVEL_VERBOSE:
 	case LOG_LEVEL_DEBUG: return ANSI("37;2");
 	case LOG_LEVEL_INFO: return ANSI("92");
 	case LOG_LEVEL_WARN: return ANSI("33");

From fd9c52d0ee97154a84433b48a4a4f2beecb25053 Mon Sep 17 00:00:00 2001
From: Bernd Busse <bernd@busse-net.de>
Date: Thu, 19 Jan 2023 23:52:58 +0100
Subject: [PATCH 17/17] backend: xrender: force 32bit ARGB visual when adding
 rounded corners

Force the temporary picture to a 32-bit ARGB visual when masking it for
rounded corners to keep the transparency information. Otherwise, windows
with a 24-bit visual would get black corners instead.

Authored-by: Bernd Busse <bernd@busse-net.de>
Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>
---
 src/backend/xrender/xrender.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/src/backend/xrender/xrender.c b/src/backend/xrender/xrender.c
index 5d04ff272b..b2ec3f2301 100644
--- a/src/backend/xrender/xrender.c
+++ b/src/backend/xrender/xrender.c
@@ -250,10 +250,16 @@ compose_impl(struct _xrender_data *xd, struct xrender_image *xrimg, coord_t dst,
 	}
 	if (((img->color_inverted || img->dim != 0) && has_alpha) || img->corner_radius != 0) {
 		// Apply image properties using a temporary image, because the source
-		// image is transparent. Otherwise the properties can be applied directly
-		// on the target image.
+		// image is transparent or will get transparent corners. Otherwise the
+		// properties can be applied directly on the target image.
+		// Also force a 32-bit ARGB visual for transparent corners, otherwise the
+		// corners become black.
+		auto visual =
+		    (img->corner_radius != 0 && inner->depth != 32)
+		        ? x_get_visual_for_standard(xd->base.c, XCB_PICT_STANDARD_ARGB_32)
+		        : inner->visual;
 		auto tmp_pict = x_create_picture_with_visual(
-		    xd->base.c, inner->width, inner->height, inner->visual, 0, NULL);
+		    xd->base.c, inner->width, inner->height, visual, 0, NULL);
 
 		// Set clip region translated to source coordinate
 		x_set_picture_clip_region(xd->base.c, tmp_pict, to_i16_checked(-dst.x),