utils: begin supporting new NDKs when building

Add support for multiple NDKs for Android SDKs to be built. This is in
preparation to migrate to r27c as the default NDK to use.

Author: compnerd

utils/build.ps1

@@ -139,7 +139,7 @@ param
   [string] $PinnedToolchainVariant = "Asserts",
   [string] $PythonVersion = "3.9.10",
   [ValidatePattern("^r(?:[1-9]|[1-9][0-9])(?:[a-z])?$")]
-  [string] $AndroidNDKVersion = "r26b",
+  [string] $AndroidNDKVersion = "r27c",
   [ValidatePattern("^\d+\.\d+\.\d+(?:-\w+)?")]
   [string] $WinSDKVersion = "",
   [switch] $Android = $false,
@@ -346,13 +346,32 @@ $BuildArch = switch ($BuildArchName) {
   default { throw "Unsupported processor architecture" }
 }
 
+$KnownNDKs = @{
+  r26b = @{
+    URL = "https://dl.google.com/android/repository/android-ndk-r26b-windows.zip"
+    SHA256 = "A478D43D4A45D0D345CDA6BE50D79642B92FB175868D9DC0DFC86181D80F691E"
+    ClangVersion = 17
+  }
+  r27c = @{
+    URL = "https://dl.google.com/android/repository/android-ndk-r27c-windows.zip"
+    SHA256 = "27E49F11E0CEE5800983D8AF8F4ACD5BF09987AA6F790D4439DDA9F3643D2494"
+    ClangVersion = 18
+  }
+}
+
+
 $IsCrossCompiling = $HostArchName -ne $BuildArchName
 
 $TimingData = New-Object System.Collections.Generic.List[System.Object]
 
+function Get-AndroidNDK {
+  $NDK = $KnownNDKs[$AndroidNDKVersion]
+  if ($NDK -eq $null) { throw "Unsupported Android NDK version" }
+  return $NDK
+}
+
 function Get-AndroidNDKPath {
-  $androidNDKPath = Join-Path -Path $BinaryCache -ChildPath "android-ndk-$AndroidNDKVersion"
-  return $androidNDKPath
+  return Join-Path -Path $BinaryCache -ChildPath "android-ndk-$AndroidNDKVersion"
 }
 
 function Get-FlexExecutable {
@@ -859,14 +878,8 @@ function Fetch-Dependencies {
   Install-PythonModules
 
   if ($Android) {
-    # Only a specific NDK version is supported right now.
-    if ($AndroidNDKVersion -ne "r26b") {
-      throw "Unsupported Android NDK version"
-    }
-    $NDKURL = "https://dl.google.com/android/repository/android-ndk-r26b-windows.zip"
-    $NDKHash = "A478D43D4A45D0D345CDA6BE50D79642B92FB175868D9DC0DFC86181D80F691E"
-    DownloadAndVerify $NDKURL "$BinaryCache\android-ndk-$AndroidNDKVersion-windows.zip" $NDKHash
-
+    $NDK = Get-AndroidNDK
+    DownloadAndVerify $NDK.URL "$BinaryCache\android-ndk-$AndroidNDKVersion-windows.zip" $NDK.SHA256
     Extract-ZipFile -ZipFileName "android-ndk-$AndroidNDKVersion-windows.zip" -BinaryCache $BinaryCache -ExtractPath "android-ndk-$AndroidNDKVersion" -CreateExtractPath $false
   }
 
@@ -1104,9 +1117,6 @@ function Build-CMakeProject {
       TryAdd-KeyValue $Defines SWIFT_ANDROID_NDK_PATH "$androidNDKPath"
       TryAdd-KeyValue $Defines CMAKE_C_COMPILER_WORKS YES
       TryAdd-KeyValue $Defines CMAKE_CXX_COMPILER_WORKS YES
-      # The current Android NDK ships with Clang 17,
-      # which doesn't provide the _Builtin_float module.
-      TryAdd-KeyValue $Defines SWIFT_BUILD_CLANG_OVERLAYS_SKIP_BUILTIN_FLOAT YES
     }
 
     TryAdd-KeyValue $Defines CMAKE_BUILD_TYPE Release
@@ -1256,7 +1266,7 @@ function Build-CMakeProject {
               "-Xclang-linker", "--sysroot",
               "-Xclang-linker", "$androidNDKPath\toolchains\llvm\prebuilt\windows-x86_64\sysroot",
               "-Xclang-linker", "-resource-dir",
-              "-Xclang-linker", "$androidNDKPath\toolchains\llvm\prebuilt\windows-x86_64\lib\clang\17"
+              "-Xclang-linker", "$androidNDKPath\toolchains\llvm\prebuilt\windows-x86_64\lib\clang\$($(Get-AndroidNDK).ClangVersion)"
             )
           }
         }
@@ -2064,16 +2074,17 @@ function Build-CURL([Platform]$Platform, $Arch) {
 
 function Build-Runtime([Platform]$Platform, $Arch) {
   $PlatformDefines = @{}
-  if ($Platform -eq "Android") {
+  if ($Platform -eq [Platform]::Android) {
     $PlatformDefines += @{
       LLVM_ENABLE_LIBCXX = "YES";
       SWIFT_USE_LINKER = "lld";
       SWIFT_INCLUDE_TESTS = "NO";
       SWIFT_INCLUDE_TEST_BINARIES = "NO";
+      # Clang[<18] doesn't provide the _Builtin_float module.
+      SWIFT_BUILD_CLANG_OVERLAYS_SKIP_BUILTIN_FLOAT = "YES";
     }
   }
 
-
   Isolate-EnvVars {
     $env:Path = "$(Get-CMarkBinaryCache $Arch)\src;$(Get-PinnedToolchainRuntime);${env:Path}"