[cxx-interop][stdlib] windows - use new hash inline functions like other platforms

stdlib/public/Cxx/cxxshim/libcxxstdlibshim.h

@@ -4,19 +4,19 @@
 
 /// Used for std::string conformance to Swift.Hashable
 typedef std::hash<std::string> __swift_interopHashOfString;
-inline std::size_t __swift_interopComputeHashOfString(std::string str) {
+inline std::size_t __swift_interopComputeHashOfString(const std::string &str) {
   return __swift_interopHashOfString()(str);
 }
 
 /// Used for std::u16string conformance to Swift.Hashable
 typedef std::hash<std::u16string> __swift_interopHashOfU16String;
-inline std::size_t __swift_interopComputeHashOfU16String(std::u16string str) {
+inline std::size_t __swift_interopComputeHashOfU16String(const std::u16string &str) {
   return __swift_interopHashOfU16String()(str);
 }
 
 /// Used for std::u32string conformance to Swift.Hashable
 typedef std::hash<std::u32string> __swift_interopHashOfU32String;
-inline std::size_t __swift_interopComputeHashOfU32String(std::u32string str) {
+inline std::size_t __swift_interopComputeHashOfU32String(const std::u32string &str) {
   return __swift_interopHashOfU32String()(str);
 }
 

stdlib/public/Cxx/std/String.swift

@@ -198,11 +198,7 @@ extension std.string: Hashable {
   @_alwaysEmitIntoClient
   public func hash(into hasher: inout Hasher) {
     // Call std::hash<std::string>::operator()
-#if os(Windows) // FIXME: https://github.com/swiftlang/swift/issues/77856
-    let cxxHash = __swift_interopHashOfString().callAsFunction(self)
-#else
     let cxxHash = __swift_interopComputeHashOfString(self)
-#endif
     hasher.combine(cxxHash)
   }
 }
@@ -211,11 +207,7 @@ extension std.u16string: Hashable {
   @_alwaysEmitIntoClient
   public func hash(into hasher: inout Hasher) {
     // Call std::hash<std::u16string>::operator()
-#if os(Windows) // FIXME: https://github.com/swiftlang/swift/issues/77856
-    let cxxHash = __swift_interopHashOfU16String().callAsFunction(self)
-#else
     let cxxHash = __swift_interopComputeHashOfU16String(self)
-#endif
     hasher.combine(cxxHash)
   }
 }
@@ -224,11 +216,7 @@ extension std.u32string: Hashable {
   @_alwaysEmitIntoClient
   public func hash(into hasher: inout Hasher) {
     // Call std::hash<std::u32string>::operator()
-#if os(Windows) // FIXME: https://github.com/swiftlang/swift/issues/77856
-    let cxxHash = __swift_interopHashOfU32String().callAsFunction(self)
-#else
     let cxxHash = __swift_interopComputeHashOfU32String(self)
-#endif
     hasher.combine(cxxHash)
   }
 }

test/Interop/Cxx/stdlib/Inputs/module.modulemap

@@ -40,6 +40,12 @@ module StdString {
   export *
 }
 
+module StdStringAndVector {
+  header "std-string-and-vector.h"
+  requires cplusplus
+  export *
+}
+
 module StdStringView {
   header "std-string-view.h"
   requires cplusplus

test/Interop/Cxx/stdlib/Inputs/std-string-and-vector.h

@@ -0,0 +1,11 @@
+#include <string>
+#include <vector>
+
+struct Item {
+  std::vector<std::string> keys;
+  std::vector<std::string> values;
+};
+
+inline Item get_item() {
+  return {};
+}

test/Interop/Cxx/stdlib/use-std-string-with-opts.swift

@@ -0,0 +1,20 @@
+// RUN: %target-run-simple-swift(-I %S/Inputs -cxx-interoperability-mode=default -Xcc -std=c++20 -O)
+//
+// REQUIRES: executable_test
+
+// Tests optimizations related to CxxStdlib.
+
+import StdlibUnittest
+import CxxStdlib
+import StdStringAndVector
+
+var StdStringOptTestSuite = TestSuite("StdStringWithOpts")
+
+StdStringOptTestSuite.test("std::string with Hashable conformance optimized") {
+    let item = get_item()
+    let dict = Dictionary(uniqueKeysWithValues: zip(item.keys, item.values).lazy)
+
+    expectEqual(dict.count, 0)
+}
+
+runAllTests()