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

Similarly to how #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.

Author: artemcm

include/swift/AST/ClangModuleLoader.h

@@ -140,6 +140,7 @@ class ClangModuleLoader : public ModuleLoader {
   /// (The implementing `ClangImporter` class maintains separate Target info
   /// for use by IRGen/CodeGen clients)
   virtual clang::TargetInfo &getModuleAvailabilityTarget() const = 0;
+  virtual clang::TargetInfo &getTargetInfo() const = 0;
 
   virtual clang::ASTContext &getClangASTContext() const = 0;
   virtual clang::Preprocessor &getClangPreprocessor() const = 0;

include/swift/ClangImporter/ClangImporter.h

@@ -570,7 +570,7 @@ class ClangImporter final : public ClangModuleLoader {
   /// instead. To distinguish IRGen clients from module loading clients,
   /// `getModuleAvailabilityTarget` should be used instead by module-loading
   /// clients.
-  clang::TargetInfo &getTargetInfo() const;
+  clang::TargetInfo &getTargetInfo() const override;
   clang::CodeGenOptions &getCodeGenOpts() const;
 
   std::string getClangModuleHash() const;

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/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 +1,63 @@
+// REQUIRES: objc_interop
+// 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
+
+//--- 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=15.00))), apply_to=function)
+extern int funcBar(void);
+#pragma clang attribute pop
+
+//--- test.swift
+import Bar
+public func foo() {
+    if #available(macOS 15.0, *), funcBar() != 0 {
+        print("Hello, World!")
+    }
+}