[clang] [clang][modules] Built-in modules are not correctly enabled for Mac Catalyst (PR #104872)

[Ian Anderson via cfe-commits]

https://github.com/ian-twilightcoder updated https://github.com/llvm/llvm-project/pull/104872

>From 2203d4437fd2a535cc559bcfbf0a41b5d6acf1cc Mon Sep 17 00:00:00 2001
From: Ian Anderson <iana at apple.com>
Date: Mon, 19 Aug 2024 15:01:33 -0700
Subject: [PATCH] [clang][modules] Built-in modules are not correctly enabled
 for Mac Catalyst

Mac Catalyst is the iOS platform, but it builds against the macOS SDK and so it needs to be checking the macOS SDK version instead of the iOS one.
Add tests against a greater-than SDK version just to make sure this works beyond the initially supporting SDKs.
---
 clang/lib/Driver/ToolChains/Darwin.cpp                 | 10 +++++++++-
 .../test/Driver/Inputs/MacOSX15.1.sdk/SDKSettings.json |  1 +
 clang/test/Driver/darwin-builtin-modules.c             |  3 +++
 3 files changed, 13 insertions(+), 1 deletion(-)
 create mode 100644 clang/test/Driver/Inputs/MacOSX15.1.sdk/SDKSettings.json

diff --git a/clang/lib/Driver/ToolChains/Darwin.cpp b/clang/lib/Driver/ToolChains/Darwin.cpp
index ee6890d5b98f0e..2550541a438481 100644
--- a/clang/lib/Driver/ToolChains/Darwin.cpp
+++ b/clang/lib/Driver/ToolChains/Darwin.cpp
@@ -2953,7 +2953,15 @@ static bool sdkSupportsBuiltinModules(
   case Darwin::MacOS:
     return SDKVersion >= VersionTuple(15U);
   case Darwin::IPhoneOS:
-    return SDKVersion >= VersionTuple(18U);
+    switch (TargetEnvironment) {
+    case Darwin::MacCatalyst:
+      // Mac Catalyst uses `-target arm64-apple-ios18.0-macabi` so the platform
+      // is iOS, but it builds with the macOS SDK, so it's the macOS SDK version
+      // that's relevant.
+      return SDKVersion >= VersionTuple(15U);
+    default:
+      return SDKVersion >= VersionTuple(18U);
+    }
   case Darwin::TvOS:
     return SDKVersion >= VersionTuple(18U);
   case Darwin::WatchOS:
diff --git a/clang/test/Driver/Inputs/MacOSX15.1.sdk/SDKSettings.json b/clang/test/Driver/Inputs/MacOSX15.1.sdk/SDKSettings.json
new file mode 100644
index 00000000000000..d46295b2ab5a17
--- /dev/null
+++ b/clang/test/Driver/Inputs/MacOSX15.1.sdk/SDKSettings.json
@@ -0,0 +1 @@
+{"Version":"15.1", "MaximumDeploymentTarget": "15.1.99"}
diff --git a/clang/test/Driver/darwin-builtin-modules.c b/clang/test/Driver/darwin-builtin-modules.c
index ec515133be8aba..4564d7317d7abe 100644
--- a/clang/test/Driver/darwin-builtin-modules.c
+++ b/clang/test/Driver/darwin-builtin-modules.c
@@ -8,5 +8,8 @@
 
 // RUN: %clang -isysroot %S/Inputs/MacOSX15.0.sdk -target x86_64-apple-macos14.0 -### %s 2>&1 | FileCheck --check-prefix=CHECK_FUTURE %s
 // RUN: %clang -isysroot %S/Inputs/MacOSX15.0.sdk -target x86_64-apple-macos15.0 -### %s 2>&1 | FileCheck --check-prefix=CHECK_FUTURE %s
+// RUN: %clang -isysroot %S/Inputs/MacOSX15.0.sdk -target x86_64-apple-ios18.0-macabi -### %s 2>&1 | FileCheck --check-prefix=CHECK_FUTURE %s
+// RUN: %clang -isysroot %S/Inputs/MacOSX15.1.sdk -target x86_64-apple-macos15.1 -darwin-target-variant x86_64-apple-ios18.1-macabi -### %s 2>&1 | FileCheck --check-prefix=CHECK_FUTURE %s
+// RUN: %clang -isysroot %S/Inputs/MacOSX15.1.sdk -target x86_64-apple-ios18.1-macabi -darwin-target-variant x86_64-apple-macos15.1 -### %s 2>&1 | FileCheck --check-prefix=CHECK_FUTURE %s
 // RUN: %clang -isysroot %S/Inputs/DriverKit23.0.sdk -target arm64-apple-driverkit23.0 -### %s 2>&1 | FileCheck --check-prefix=CHECK_FUTURE %s
 // CHECK_FUTURE-NOT: -fbuiltin-headers-in-system-modules