IRGen: rework linking against CxxStdlib

Rewrite the handling for the `CxxStdlib` implicit linking to use a
slightly more functional style for filtering.  Additionally, add Windows
to the list providing the overlay.  The Windows linking scenario is a
slightly more complicated as the library names differ between static and
dynamic variants to disambiguate between import libraries and static
libraries.  Take this into account when embedding the library name so
that the linker can find the appropriate content.

Author: compnerd

lib/IRGen/GenDecl.cpp

@@ -491,13 +491,32 @@ void IRGenModule::emitSourceFile(SourceFile &SF) {
     if (!getSwiftModule()->getName().is("Cxx"))
       this->addLinkLibrary(LinkLibrary("swiftCxx", LibraryKind::Library));
 
-    // Only link with CxxStdlib on platforms where the overlay is available.
-    // Do not try to link CxxStdlib with itself.
-    if ((target.isOSDarwin() || (target.isOSLinux() && !target.isAndroid())) &&
-        !getSwiftModule()->getName().is("Cxx") &&
-        !getSwiftModule()->getName().is("CxxStdlib") &&
-        !getSwiftModule()->getName().is("std")) {
-      this->addLinkLibrary(LinkLibrary("swiftCxxStdlib", LibraryKind::Library));
+    // Do not try to link CxxStdlib with the C++ standard library, Cxx or
+    // itself.
+    if (llvm::none_of(llvm::ArrayRef{"Cxx", "CxxStdlib", "std"},
+                      [M = getSwiftModule()->getName().str()](StringRef Name) {
+                        return M == Name;
+                      })) {
+      // Only link with CxxStdlib on platforms where the overlay is available.
+      switch (target.getOS()) {
+      case llvm::Triple::Linux:
+        if (!target.isAndroid())
+          this->addLinkLibrary(LinkLibrary("swiftCxxStdlib",
+                                           LibraryKind::Library));
+        break;
+      case llvm::Triple::Win32: {
+        bool isStatic = Context.getModuleByName("CxxStdlib")->isStaticLibrary();
+        this->addLinkLibrary(
+            LinkLibrary(isStatic ? "libswiftCxxStdlib" : "swiftCxxStdlib",
+                        LibraryKind::Library));
+        break;
+      }
+      default:
+        if (target.isOSDarwin())
+          this->addLinkLibrary(LinkLibrary("swiftCxxStdlib",
+                                           LibraryKind::Library));
+        break;
+      }
     }
   }
 

test/Interop/Cxx/class/constructors-copy-irgen-windows.swift

@@ -1,6 +1,6 @@
 // Target-specific tests for C++ copy constructor code generation.
 
-// RUN: %swift -module-name MySwift -target x86_64-unknown-windows-msvc -dump-clang-diagnostics -I %S/Inputs -enable-experimental-cxx-interop -emit-ir %s -parse-stdlib -parse-as-library -disable-legacy-type-info | %FileCheck %s -check-prefix=MICROSOFT_X64
+// RUN: %swift -module-name MySwift -target x86_64-unknown-windows-msvc %target-swift-flags -dump-clang-diagnostics -I %S/Inputs -enable-experimental-cxx-interop -emit-ir %s -parse-stdlib -parse-as-library -disable-legacy-type-info | %FileCheck %s -check-prefix=MICROSOFT_X64
 
 // REQUIRES: OS=windows-msvc
 // REQUIRES: CPU=x86_64

test/Interop/Cxx/class/constructors-irgen-windows.swift

@@ -1,6 +1,6 @@
 // Target-specific tests for C++ constructor call code generation.
 
-// RUN: %swift -module-name MySwift -target x86_64-unknown-windows-msvc -dump-clang-diagnostics -I %S/Inputs -enable-experimental-cxx-interop -emit-ir %s -parse-stdlib -parse-as-library -disable-legacy-type-info | %FileCheck %s -check-prefix=MICROSOFT_X64
+// RUN: %swift -module-name MySwift -target x86_64-unknown-windows-msvc %target-swift-flags -dump-clang-diagnostics -I %S/Inputs -enable-experimental-cxx-interop -emit-ir %s -parse-stdlib -parse-as-library -disable-legacy-type-info | %FileCheck %s -check-prefix=MICROSOFT_X64
 
 // REQUIRES: OS=windows-msvc
 // REQUIRES: CPU=x86_64

test/Interop/Cxx/class/copy-move-assignment-irgen.swift

@@ -1,4 +1,4 @@
-// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -I %S/Inputs -enable-experimental-cxx-interop -emit-ir %s -Xcc -fignore-exceptions -O | %FileCheck %s
+// RUN: %target-swift-frontend -I %S/Inputs -enable-experimental-cxx-interop -emit-ir %s -Xcc -fignore-exceptions -O | %FileCheck %s
 
 import CopyMoveAssignment
 

test/Interop/Cxx/class/destructors-correct-abi-irgen.swift

@@ -1,4 +1,4 @@
-// RUN: %swift -I %S/Inputs -enable-experimental-cxx-interop -emit-ir %s | %FileCheck %s
+// RUN: %swift %target-swift-flags -I %S/Inputs -enable-experimental-cxx-interop -emit-ir %s | %FileCheck %s
 
 import Destructors
 

test/Interop/Cxx/foreign-reference/Inputs/move-only.h

@@ -2,11 +2,7 @@
 #define TEST_INTEROP_CXX_FOREIGN_REFERENCE_INPUTS_MOVE_ONLY_H
 
 #include <stdlib.h>
-#if defined(_WIN32)
-inline void *operator new(size_t, void *p) { return p; }
-#else
 #include <new>
-#endif
 
 #include "visibility.h"
 

test/Interop/Cxx/foreign-reference/Inputs/nullable.h

@@ -2,11 +2,7 @@
 #define TEST_INTEROP_CXX_FOREIGN_REFERENCE_INPUTS_NULLABLE_H
 
 #include <stdlib.h>
-#if defined(_WIN32)
-inline void *operator new(size_t, void *p) { return p; }
-#else
 #include <new>
-#endif
 
 struct __attribute__((swift_attr("import_reference")))
 __attribute__((swift_attr("retain:immortal")))

test/Interop/Cxx/foreign-reference/Inputs/singleton.h

@@ -2,11 +2,7 @@
 #define TEST_INTEROP_CXX_FOREIGN_REFERENCE_INPUTS_SINGLETON_H
 
 #include <stdlib.h>
-#if defined(_WIN32)
-inline void *operator new(size_t, void *p) { return p; }
-#else
 #include <new>
-#endif
 
 #include "visibility.h"
 

test/Interop/Cxx/stdlib/use-std-pair.swift

@@ -1,5 +1,5 @@
 // RUN: %target-run-simple-swift(-I %S/Inputs -Xfrontend -enable-experimental-cxx-interop)
-//
+
 // REQUIRES: executable_test
 
 import StdlibUnittest
@@ -15,7 +15,6 @@ StdPairTestSuite.test("StdPairInts.init") {
   expectEqual(pi.second, 2)
 }
 
-#if !os(Windows) // FIXME: enable once swiftCxxStdlib is built on Windows (https://github.com/apple/swift/issues/67649)
 StdPairTestSuite.test("StdPairStrings.init") {
   let ps = PairStrings(first: std.string(), second: std.string())
   expectEqual(ps.first, std.string())
@@ -25,7 +24,6 @@ StdPairTestSuite.test("StdPairStrings.init") {
   expectEqual(ps2.first, std.string("abc"))
   expectEqual(ps2.second, std.string("123"))
 }
-#endif
 
 StdPairTestSuite.test("StdPair.elements") {
   var pi = getIntPair()

test/Interop/Cxx/union/anonymous-union-partly-invalid.swift

@@ -1,4 +1,4 @@
-// RUN: %swift -I %S/Inputs -enable-experimental-cxx-interop -enable-objc-interop -emit-ir %s -Xcc -fignore-exceptions | %FileCheck %s
+// RUN: %swift %target-swift-flags -I %S/Inputs -enable-experimental-cxx-interop -enable-objc-interop -emit-ir %s -Xcc -fignore-exceptions | %FileCheck %s
 
 import AnonymousUnionPartlyInvalid
 

test/Interop/lit.local.cfg

@@ -28,13 +28,18 @@ if is_cf_options_interop_updated:
     config.available_features.add('cxx-interop-fixed-cf_options')
 
 if get_target_os() in ['windows-msvc']:
+    import os
     config.substitutions.insert(0, ('%target-abi', 'WIN'))
     # Clang should build object files with link settings equivalent to -libc MD
     # when building for the MSVC target.
     clang_opt = clang_compile_opt + '-D_MT -D_DLL -Xclang --dependent-lib=msvcrt -Xclang --dependent-lib=oldnames '
+    config.substitutions.insert(0, ('%target-swift-flags', '-vfsoverlay {}'.format(os.path.join(config.swift_obj_root,
+                                                            'stdlib',
+                                                            'windows-vfs-overlay.yaml'))))
 else:
     # FIXME(compnerd) do all the targets we currently support use SysV ABI?
     config.substitutions.insert(0, ('%target-abi', 'SYSV'))
+    config.substitutions.insert(0, ('%target-swift-flags', ''))
 
 # Enable C++ interop when compiling Swift sources.
 config.substitutions.insert(0, ('%target-interop-build-swift',