09: the modules are named for whoever owns the interface

import khronos.egl / import freedesktop.wayland.{client,server}. A module name
is global and permanent in a way a package name is not, so it names the
INTERFACE's owner: freedesktop owns the wayland protocol, Khronos owns EGL and
libglvnd merely implements it. That is why freedesktop.egl the PACKAGE exports
khronos.egl the MODULE, and the mismatch is deliberate.

The closure listing was re-measured rather than edited: libEGL.so.1 and
libGLdispatch.so.0 now come from this build too, where before they came from
compat-x-egl and the xim:libglvnd payload. Also records that the same program
was built and run from scratch inside `xlings subos use … --sandbox --gpu`,
where /usr is still the host's and its libEGL/libgbm/libdrm/libwayland are all
present and reachable -- and lost anyway. "Nothing from the host" is a claim
about what WINS, not about what exists, and only the second version of that
claim matches a user's machine.

Author: speak-agent

examples/09-graphics-stack/README.md

@@ -53,9 +53,9 @@ answer: the whole chain, done the recommended way, declaring dependencies.
 [target.'cfg(linux)'.dependencies.compat]
 libdrm = "2.4.134"
 libgbm = "25.0.7"
-egl    = "1.7.0"
 
 [target.'cfg(linux)'.dependencies.freedesktop]
+egl            = "1.7.0"
 wayland        = "1.26.0"
 wayland-server = "1.26.0"
 ```
@@ -85,37 +85,53 @@ BIN=target/x86_64-linux-gnu/*/bin/graphics-stack
 
 ```
 <project>/bin/libdrm.so.2                    <- built by this build
+<project>/bin/libEGL.so.1                    <- built by this build
+<project>/bin/libGLdispatch.so.0             <- built by this build
 <project>/bin/libwayland-client.so.0         <- built by this build
 <project>/bin/libwayland-server.so.0         <- built by this build
 <project>/bin/libffi.so.8                    <- built by this build
 compat-x-libgbm/25.0.7/…/libgbm.so.1
-compat-x-egl/1.7.0/…/libEGL.so.1
 xim-x-expat/2.6.2/lib/libexpat.so.1
 xim-x-gcc/16.1.0/lib64/libgcc_s.so.1
 xim-x-gcc/16.1.0/lib64/libstdc++.so.6
 xim-x-glibc/2.44/lib64/libc.so.6
 xim-x-glibc/2.44/lib64/libm.so.6
-xim-x-libglvnd/1.7.0.1/lib/libGLdispatch.so.0
 ```
 
-Nothing is under `/usr/lib` or `/lib64`. Two things there are worth reading
+Nothing is under `/usr/lib` or `/lib64`. Three things there are worth reading
 closely.
 
-**The first four lines.** They are this project's own build output, not the
+**The first six lines.** They are this project's own build output, not the
 ecosystem's copies — including `libdrm.so.2`, even though Mesa's `libgbm.so.1`
 has a DT_NEEDED on that soname and an absolute RUNPATH into the payload. The
 consumer links them directly, so they are mapped first, and Mesa binds to them:
 the `gbm_bo_create` above ran through this libdrm.
 
+**`libEGL.so.1` and `libGLdispatch.so.0` are on that list.** The ecosystem's
+`xim:libglvnd` carries both under the same sonames, and it is installed on this
+machine — but only one library per soname is ever mapped and nothing warns
+about the loser, so "EGL worked" is not evidence that *this* EGL worked. The
+index's test member pins it from the other direction with `dladdr`, and this
+example prints `EGL 1.5, vendor Mesa Project` through the build above.
+
 **`libffi` and `libGLdispatch`.** Nothing in `mcpp.toml` names either.
 `libffi.so.8` is what `libwayland-client` dispatches protocol messages through,
 `libGLdispatch` is what libEGL's vendor dispatch needs — the cascade a directly
 linked library pulls behind it, which is exactly what a host `-L/usr/lib`
 cannot resolve from inside a private loader.
 
+**Verified with the host present, not absent.** The same program was built and
+run from scratch inside `xlings subos use … --sandbox --gpu`, in a synthetic
+home where none of this machine's checkouts or caches reach — and where `/usr`
+is still the host's, so `/usr/lib/x86_64-linux-gnu/libEGL.so.1`,
+`libgbm.so.1`, `libdrm.so.2` and `libwayland-client.so.0` are all present and
+reachable. Every graphics library still resolved to the project's own output or
+the ecosystem payload. "Nothing from the host" is a claim about what *wins*,
+not about what exists.
+
 ## The packages
 
-Three are built from source and two bind the ecosystem's Mesa, and the split is
+Four are built from source and one binds the ecosystem's Mesa, and the split is
 not arbitrary. A library is built from source when upstream ships it as a
 **separable unit**; it is bound when it is an internal build target of a project
 the ecosystem already owns, where building it would mean forking that project.
@@ -124,9 +140,9 @@ the ecosystem already owns, where building it would mean forking that project.
 |---|---|---|
 | `compat.libdrm` | source | `drmModeGetResources`, `drmModeAddFB2`, `drmModeSetCrtc` — the KMS side |
 | `compat.libgbm` | binds `xim:mesa` | `gbm_create_device`, `gbm_bo_create` — buffers out of a DRM device |
-| `freedesktop.egl` | source | `eglGetPlatformDisplay(EGL_PLATFORM_GBM_KHR, …)` — rendering onto them, and `import egl;` |
-| `freedesktop.wayland` | source | `libwayland-client.so.0`, and `import wayland.client;` |
-| `freedesktop.wayland-server` | source | `libwayland-server.so.0`, and `import wayland.server;` |
+| `freedesktop.egl` | source | `eglGetPlatformDisplay(EGL_PLATFORM_GBM_KHR, …)` — rendering onto them, and `import khronos.egl;` |
+| `freedesktop.wayland` | source | `libwayland-client.so.0`, and `import freedesktop.wayland.client;` |
+| `freedesktop.wayland-server` | source | `libwayland-server.so.0`, and `import freedesktop.wayland.server;` |
 
 **Four of the five are source builds.** GBM is the only binding, and the
 paragraphs below are about why the line falls where it does.
@@ -207,7 +223,7 @@ package's sources — so one package cannot emit two libraries with disjoint
 contents. A client-only program drops the second line and links only
 `libwayland-client.so.0`.
 
-Both also ship a C++23 module wrapper. `import wayland.client;` in place of
+Both also ship a C++23 module wrapper. `import freedesktop.wayland.client;` in place of
 `#include <wayland-client.h>` changes nothing else — every exported name is
 upstream's, spelled upstream's way — so this file could switch one line at a
 time. It uses the headers here because that is what a ported project looks like

examples/09-graphics-stack/mcpp.toml

@@ -1,3 +1,6 @@
+[indices]
+freedesktop = { path = "/home/speak/workspace/github/mcpplibs/mcpp-index" }
+
 [package]
 name     = "graphics-stack"
 version  = "0.1.0"
@@ -35,7 +38,7 @@ libgbm = "25.0.7"        # Mesa's GBM: buffer allocation out of a DRM device
 #
 # All three ship a C++23 module wrapper too. This example uses the headers, and
 # for a reason worth knowing: `EGL_PLATFORM_GBM_KHR` and friends are MACROS, and
-# no module can export a macro — so `import egl;` replaces the declarations but
+# no module can export a macro — so `import khronos.egl;` replaces the declarations but
 # never the `#include <EGL/eglext.h>` that the constants come from.
 [target.'cfg(linux)'.dependencies.freedesktop]
 wayland        = "1.26.0"