feat(libdisplay-info): 生成全部走 build.mcpp,并带模块 (#308)

按规范重做:fork 的生成物不再用 sh + python 预生成再签进仓,改由 build.mcpp
产出——它是 C++,mcpp 编译并运行它,所以这个包不需要 python3、sh 或任何外部工具。

  pnp-id-table.c            2583 行厂商表,写进 out dir
  src/libdisplay-info.cppm  模块包装,206 个名字(130 类型 + 76 函数)

没有签进仓的生成物,也就没有「重生成再 diff」的 CI 步骤——数据与代码不一致
这个状态不存在。这是构建期生成和签生成物的本质区别。

模块解决一个真问题:七个公共头一个 extern "C" 都没有,C++ 消费者 #include 会
mangle 到链接失败。测试成员之前就得自己包一层;现在 import freedesktop.displayinfo;
把包装做在模块内。测试已改成 import 并通过,证明经索引也可用。

顺带:build.mcpp 的表比上游生成器更正确。pnp.ids 里 U+00A0 编码是 c2 a0 两字节,
上游按文本读、按码点转义成 \240(单字节,不是 UTF-8);build.mcpp 按字节转义成
\302\240。全文件 diff:2583 行,除几个非 ASCII 名字外完全一致。

只改了 pkgs/ 与 tests/examples/。

Author: Sunrisepeak

pkgs/f/freedesktop.libdisplay-info.lua

@@ -24,18 +24,35 @@
 -- tables generated from them by 15 (2568 vs 2583) — so an unpinned build makes
 -- `di_info_get_make` answer differently depending on where it was compiled.
 --
--- The fork pins hwdata v0.410, checks the input in beside the output, and its
--- CI regenerates and diffs. Same arrangement as freedesktop.libevdev with
--- upstream's bundled kernel headers.
---
--- NO MODULE WRAPPER, deliberately: this library's consumer is wlroots, which is
--- C, and the surface is 74 functions over ~360 structs. The design doc's rule
--- applies — the module layer is a RESULT of forking, not a reason to fork.
---
--- ⚠ C++ CONSUMERS MUST WRAP THE INCLUDES. Not one of the seven public headers
--- has an `extern "C"` block, so a C++ TU mangles every declaration and the link
--- fails with `undefined reference to di_info_get_make(di_info const*)` — naming
--- a symbol that is right there. Same as compat.libseat.
+-- The fork pins hwdata v0.410 and checks it in as an INPUT. There is no
+-- checked-in output and no regenerate-and-diff CI step, because there is
+-- nothing to keep honest: `build.mcpp` PRODUCES the table during the build.
+--
+-- NOTHING IN THIS PACKAGE NEEDS python3, sh OR ANY OTHER TOOL. `build.mcpp` is
+-- C++ that mcpp compiles and runs, and it does every generated artifact:
+--
+--     pnp-id-table.c            2,583 lines, into the out dir
+--     src/libdisplay-info.cppm  the module wrapper, 206 names
+--
+-- IT IS ALSO MORE CORRECT THAN UPSTREAM'S GENERATOR. pnp.ids stores
+-- `DemoPad<U+00A0>Software<U+00A0>Ltd`, and U+00A0 is the two bytes c2 a0.
+-- Upstream reads the file as TEXT and escapes the codepoint by ordinal —
+-- `\240`, a single byte that is not its UTF-8 encoding, so the string a
+-- consumer prints is invalid UTF-8. build.mcpp escapes BYTES. Diffed over the
+-- whole file: 2,583 lines, identical except for the handful of non-ASCII names,
+-- where this one is right.
+--
+-- THE MODULE IS GENERATED, not hand-written: 206 names read out of the public
+-- headers, so a version bump cannot silently drop one.
+--
+--     import freedesktop.displayinfo;
+--
+-- and that also removes a real burden — not one of the seven public headers has
+-- an `extern "C"` block, so a C++ TU that #includes them mangles every
+-- declaration and fails to link with `undefined reference to
+-- di_info_get_make(di_info const*)`. The module does that wrapping once, inside
+-- the module purview, so a consumer does not. (compat.libseat has the same
+-- upstream problem and no module, so there the consumer still wraps.)
 package = {
     spec        = "1",
     namespace   = "freedesktop",
@@ -49,10 +66,10 @@ package = {
         linux = {
             ["0.2.0"] = {
                 url = {
-                    GLOBAL = "https://github.com/mcpplibs/libdisplay-info/releases/download/v0.2.0/libdisplay-info-0.2.0-mcpp.tar.gz",
-                    CN     = "https://gitcode.com/mcpp-res/libdisplay-info/releases/download/0.2.0/libdisplay-info-0.2.0-mcpp.tar.gz",
+                    GLOBAL = "https://github.com/mcpplibs/libdisplay-info/releases/download/v0.2.0/libdisplay-info-0.2.0-mcpp2.tar.gz",
+                    CN     = "https://gitcode.com/mcpp-res/libdisplay-info/releases/download/0.2.0/libdisplay-info-0.2.0-mcpp2.tar.gz",
                 },
-                sha256 = "df065a6e040799536a6c93a0202f2766b8c3388b546d0ba4a43290a89aa33ccc",
+                sha256 = "8df9a8064146b2b38378bd8b146894d084ffda43b88b43c485b954da073a7617",
             },
         },
     },

tests/examples/libdisplay-info/tests/libdisplay-info.cpp

@@ -24,15 +24,19 @@
 
 #ifdef __linux__
 
-// WRAPPED, and it has to be: not one of libdisplay-info's seven public headers
-// contains an `extern "C"` block — zero occurrences, measured — so a C++
-// translation unit mangles every declaration and the link fails with
+// NO extern "C" WRAPPER, and that is the point of the module.
+//
+// Not one of libdisplay-info's seven public headers contains an `extern "C"`
+// block — zero occurrences, measured — so a C++ translation unit that
+// #includes them mangles every declaration and fails to link with
 // `undefined reference to di_info_get_make(di_info const*)`, naming a symbol
-// that is right there in the library. Same as compat.libseat.
-extern "C" {
-#include <libdisplay-info/info.h>
-#include <libdisplay-info/edid.h>
-}
+// that is right there in the library. This file did exactly that before the
+// module existed.
+//
+// `import freedesktop.displayinfo;` does the wrapping once, inside the module
+// purview. The module is GENERATED by the package's build.mcpp from the public
+// headers — 206 names — so it cannot fall behind them.
+import freedesktop.displayinfo;
 
 #include <cstdio>
 #include <cstring>