Modify clang declaration weakly-imported query to use Swift's code-gen target triple

Similarly to how https://github.com/swiftlang/swift/pull/70564 configures 'ClangImporter's 'CodeGenerator' using Swift's compilation target triple, we must use the versioned version of the 'isWeakImported' query to determine linkage for imported Clang symbols.

lib/AST/Decl.cpp

@@ -75,6 +75,7 @@
 
 #include "clang/Basic/CharInfo.h"
 #include "clang/Basic/Module.h"
+#include "clang/Basic/TargetInfo.h"
 #include "clang/AST/Attr.h"
 #include "clang/AST/DeclObjC.h"
 
@@ -1468,9 +1469,9 @@ AvailabilityRange Decl::getAvailabilityForLinkage() const {
 
 bool Decl::isAlwaysWeakImported() const {
   // For a Clang declaration, trust Clang.
-  if (auto clangDecl = getClangDecl()) {
-    return clangDecl->isWeakImported();
-  }
+  if (auto clangDecl = getClangDecl())
+    return clangDecl->isWeakImported(
+        getASTContext().LangOpts.getMinPlatformVersion());
 
   if (getAttrs().hasAttribute<WeakLinkedAttr>())
     return true;

lib/ClangImporter/ClangImporter.cpp

@@ -66,6 +66,7 @@
 #include "clang/Basic/FileEntry.h"
 #include "clang/Basic/IdentifierTable.h"
 #include "clang/Basic/LangStandard.h"
+#include "clang/Basic/MacroBuilder.h"
 #include "clang/Basic/Module.h"
 #include "clang/Basic/Specifiers.h"
 #include "clang/Basic/TargetInfo.h"
@@ -1464,8 +1465,14 @@ ClangImporter::create(ASTContext &ctx,
         importer.get(), importerOpts, VFS, *swiftTargetClangArgs);
     if (!swiftTargetClangInvocation)
       return nullptr;
-    importer->Impl.setSwiftTargetInfo(clang::TargetInfo::CreateTargetInfo(
-        clangDiags, swiftTargetClangInvocation->TargetOpts));
+    auto targetInfo = clang::TargetInfo::CreateTargetInfo(
+        clangDiags, swiftTargetClangInvocation->TargetOpts);
+    // Ensure the target info has configured target-specific defines
+    std::string defineBuffer;
+    llvm::raw_string_ostream predefines(defineBuffer);
+    clang::MacroBuilder builder(predefines);
+    targetInfo->getTargetDefines(instance.getLangOpts(), builder);
+    importer->Impl.setSwiftTargetInfo(targetInfo);
     importer->Impl.setSwiftCodeGenOptions(new clang::CodeGenOptions(
         swiftTargetClangInvocation->getCodeGenOpts()));
   } else {

lib/SIL/IR/SILFunction.cpp

@@ -618,7 +618,8 @@ bool SILFunction::isWeakImported(ModuleDecl *module) const {
 
   // For imported functions check the Clang declaration.
   if (ClangNodeOwner)
-    return ClangNodeOwner->getClangDecl()->isWeakImported();
+    return ClangNodeOwner->getClangDecl()->isWeakImported(
+        getASTContext().LangOpts.getMinPlatformVersion());
 
   // For native functions check a flag on the SILFunction
   // itself.

test/SILGen/clang-target-weak-import.swift

@@ -0,0 +1,70 @@
+// REQUIRES: objc_interop
+// REQUIRES: OS=macosx
+// RUN: %empty-directory(%t)
+// RUN: %empty-directory(%t/module-cache)
+// RUN: %empty-directory(%t/inputs)
+// RUN: %empty-directory(%t/cheaders)
+
+// RUN: split-file %s %t
+// RUN: sed -e "s|INPUTSDIR|%/t/inputs|g" %t/map.json.template > %t/map.json.template1
+// RUN: sed -e "s|STDLIBMOD|%/stdlib_module|g" %t/map.json.template1 > %t/map.json.template2
+// RUN: sed -e "s|ONONEMOD|%/ononesupport_module|g" %t/map.json.template2 > %t/map.json.template3
+// RUN: sed -e "s|CHEADERSDIR|%t/cheaders|g" %t/map.json.template3 > %t/map.json.template4
+// RUN: sed -e "s|SWIFTLIBDIR|%swift-lib-dir|g" %t/map.json.template4 > %t/map.json
+
+// RUN: %target-swift-emit-pcm -module-name Bar -o %t/inputs/Bar.pcm %t/cheaders/module.modulemap -target %target-cpu-apple-macosx15.0
+// RUN: %target-swift-emit-pcm -module-name SwiftShims %swift-lib-dir/swift/shims/module.modulemap -o %t/inputs/SwiftShims.pcm -target %target-cpu-apple-macosx15.0
+
+// RUN: %target-swift-frontend -c -disable-implicit-swift-modules -disable-implicit-concurrency-module-import -disable-implicit-string-processing-module-import -module-cache-path %t/module-cache -explicit-swift-module-map-file %t/map.json -primary-file %t/test.swift -o %t/test.o -target %target-cpu-apple-macosx14.0 -clang-target %target-cpu-apple-macosx15.0
+
+// RUN: %llvm-nm -m %t/test.o | %FileCheck %s
+// CHECK: (undefined) weak external _funcBar
+// CHECK: (undefined) external _funcBarButOlder
+
+//--- map.json.template
+[
+  {
+      "moduleName": "Bar",
+      "clangModulePath": "INPUTSDIR/Bar.pcm",
+      "clangModuleMapPath": "CHEADERSDIR/module.modulemap"
+  },
+  {
+      "moduleName": "Swift",
+      "modulePath": "STDLIBMOD",
+      "isFramework": false
+  },
+  {
+      "moduleName": "SwiftOnoneSupport",
+      "modulePath": "ONONEMOD",
+      "isFramework": false
+  },
+  {
+      "moduleName": "SwiftShims",
+      "isFramework": false,
+      "clangModuleMapPath": "SWIFTLIBDIR/swift/shims/module.modulemap",
+      "clangModulePath": "INPUTSDIR/SwiftShims.pcm"
+}]
+
+//--- cheaders/module.modulemap
+module Bar {
+  header "Bar.h"
+  export *
+}
+
+//--- cheaders/Bar.h
+#pragma clang attribute push (__attribute__((availability(macOS, introduced=15.0))), apply_to=function)
+extern int funcBar(void);
+#pragma clang attribute pop
+
+#pragma clang attribute push (__attribute__((availability(macOS, introduced=14.0))), apply_to=function)
+extern int funcBarButOlder(void);
+#pragma clang attribute pop
+
+//--- test.swift
+import Bar
+public func foo() {
+    let _ = funcBarButOlder()
+    if #available(macOS 15.0, *), funcBar() != 0 {
+        print("Hello, World!")
+    }
+}