Link the VC runtime statically into twcore.exe (#277)

twcore.exe imported VCRUNTIME140.dll, which Windows does not ship: it
comes with the Visual C++ Redistributable, usually installed by some
other program. The desktop installer only carries twcore.exe, so on a
machine without the redistributable the gateway cannot start. CI runners
and most real machines have it installed, which is why nothing showed.

- .cargo/config.toml: +crt-static for windows-msvc targets, so a local
  Windows build matches what is released. RUSTFLAGS overrides it, so the
  CI test builds stay dynamic; the release workflow does not set it.
- release.yml: a step reads both exes' imports with dumpbin and fails if
  any Visual C++ runtime DLL is still there.

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

Author: fylorn

.cargo/config.toml

@@ -0,0 +1,14 @@
+# Windows 上把 VC 运行库静态链接进 twcore.exe。
+#
+# **不加这一条，twcore.exe 依赖 VCRUNTIME140.dll**，而这个文件不随 Windows
+# 自带：它来自「Visual C++ 可再发行组件包」，一般是别的软件顺手装上的。桌面版
+# 的安装程序只放 twcore.exe、不装运行库，于是在一台没装过它的机器上，网关
+# 根本起不来 —— CI 和多数真机上都装着它，所以看不出来。UCRT 是 Windows 10
+# 起系统自带的，静态链接只是顺带把它也带上。
+#
+# 写在这里而不是 release.yml 里：本机在 Windows 上编出来的和发出去的是同一种。
+# **`RUSTFLAGS` 环境变量会整个盖掉这里**（ci.yml 设了 `-D warnings`，所以 CI
+# 的测试仍是动态链接的），发版流水线不设它；release.yml 里有一步查 twcore.exe
+# 的导入表，这一条哪天没生效会在那里失败。
+[target.'cfg(all(windows, target_env = "msvc"))']
+rustflags = ["-C", "target-feature=+crt-static"]

.github/workflows/release.yml

@@ -185,6 +185,31 @@ jobs:
           }
           & $exe --help | Out-Null
 
+      # **不要用户另装 VC 运行库。**VC 运行库由 `.cargo/config.toml` 静态链接进来；
+      # 这里查两个 exe 的导入表，里面不许有 Windows 不自带的那几个 DLL。这台
+      # runner 上装着运行库，exe 照样跑得起来 —— 上一步看不出这件事，只有导入表看得出。
+      # 用的是链接它的那套 MSVC 里的 dumpbin，arm64 的 exe 一样读得了
+      - name: No Visual C++ runtime to install
+        shell: pwsh
+        run: |
+          $ErrorActionPreference = "Stop"
+          $vswhere = "${env:ProgramFiles(x86)}\Microsoft Visual Studio\Installer\vswhere.exe"
+          $dumpbin = & $vswhere -latest -products * -find "VC\Tools\MSVC\**\bin\Hostx64\x64\dumpbin.exe" |
+            Select-Object -First 1
+          if (-not $dumpbin) { throw "dumpbin.exe not found" }
+          foreach ($t in @("x86_64-pc-windows-msvc", "aarch64-pc-windows-msvc")) {
+            $exe = "target\$t\release\twcore.exe"
+            $deps = & $dumpbin /nologo /dependents $exe |
+              ForEach-Object { $_.Trim() } |
+              Where-Object { $_ -match '\.dll$' }
+            if ($LASTEXITCODE -ne 0 -or -not $deps) { throw "could not read the imports of $exe" }
+            Write-Host "${exe}: $($deps -join ', ')"
+            $redist = @($deps | Where-Object { $_ -match '^(vcruntime|msvcp|concrt|vccorlib|vcomp)\d' })
+            if ($redist.Count -gt 0) {
+              throw "$exe needs the Visual C++ runtime ($($redist -join ', ')) -- the static CRT in .cargo/config.toml did not apply"
+            }
+          }
+
       - name: Package
         shell: pwsh
         run: |