[Module] Use stricter module hash

Use a stricter module hash for modules as moving towards more explicit
modules. Previously, a normalized target triple without deployment
target is used as part of the module hash, with the assumption that
deployment target should not change binary module generated.

In reality, the binary module compilation also needs to provide the
typecheck for all interface to ensure the underlying C/ObjC module that
built with the correct deployment target does provide the interfaces to
pass typecheck. Using a stricter module hash can avoid the potentially
confusing error when importing the module.

This commit adds following to module hash to distinguish swiftmodules.
* Deployment target
* -application-extension

rdar://134301179

Author: cachemeifyoucan

lib/Frontend/ModuleInterfaceLoader.cpp

@@ -2071,8 +2071,24 @@ StringRef InterfaceSubContextDelegateImpl::computeCachedOutputPath(
 std::string
 InterfaceSubContextDelegateImpl::getCacheHash(StringRef useInterfacePath,
                                               StringRef sdkPath) {
-  auto normalizedTargetTriple =
-      getTargetSpecificModuleTriple(genericSubInvocation.getLangOptions().Target);
+  // When doing dependency scanning for explicit module, use strict context hash
+  // to ensure sound module hash.
+  bool useStrictCacheHash =
+      genericSubInvocation.getFrontendOptions().RequestedAction ==
+      FrontendOptions::ActionType::ScanDependencies;
+
+  // Include the normalized target triple when not using strict hash.
+  // Otherwise, use the full target to ensure soundness of the hash. In
+  // practice, .swiftinterface files will be in target-specific subdirectories
+  // and would have target-specific pieces #if'd out. However, it doesn't hurt
+  // to include it, and it guards against mistakenly reusing cached modules
+  // across targets. Note that this normalization explicitly doesn't include the
+  // minimum deployment target (e.g. the '12.0' in 'ios12.0').
+  auto targetToHash = useStrictCacheHash
+                          ? genericSubInvocation.getLangOptions().Target
+                          : getTargetSpecificModuleTriple(
+                                genericSubInvocation.getLangOptions().Target);
+
   std::string sdkBuildVersion = getSDKBuildVersion(sdkPath);
   const auto ExtraArgs = genericSubInvocation.getClangImporterOptions()
                              .getReducedExtraArgsForSwiftModuleDependency();
@@ -2089,13 +2105,8 @@ InterfaceSubContextDelegateImpl::getCacheHash(StringRef useInterfacePath,
       // anyways.
       useInterfacePath,
 
-      // Include the normalized target triple. In practice, .swiftinterface
-      // files will be in target-specific subdirectories and would have
-      // target-specific pieces #if'd out. However, it doesn't hurt to include
-      // it, and it guards against mistakenly reusing cached modules across
-      // targets. Note that this normalization explicitly doesn't include the
-      // minimum deployment target (e.g. the '12.0' in 'ios12.0').
-      normalizedTargetTriple.str(),
+      // The target triple to hash.
+      targetToHash.str(),
 
       // The SDK path is going to affect how this module is imported, so
       // include it.
@@ -2121,6 +2132,10 @@ InterfaceSubContextDelegateImpl::getCacheHash(StringRef useInterfacePath,
       // module.
       llvm::hash_combine_range(ExtraArgs.begin(), ExtraArgs.end()),
 
+      /// Application extension.
+      unsigned(
+          genericSubInvocation.getLangOptions().EnableAppExtensionRestrictions),
+
       // Whether or not OSSA modules are enabled.
       //
       // If OSSA modules are enabled, we use a separate namespace of modules to

test/ScanDependencies/module_hash.swift

@@ -14,7 +14,7 @@
 // RUN:   -disable-implicit-string-processing-module-import -disable-implicit-concurrency-module-import -O \
 // RUN:   -o %t/deps-3.json -Xcc -fapplication-extension -I %t/include
 
-/// Check module hash for the swiftmodule. 1 and 2 should match, but not 3.
+/// Check module hash for the swiftmodule. They should all not match.
 // RUN: %{python} %S/../CAS/Inputs/SwiftDepsExtractor.py %t/deps-1.json Library modulePath > %t/path-1
 // RUN: %{python} %S/../CAS/Inputs/SwiftDepsExtractor.py %t/deps-2.json Library modulePath > %t/path-2
 // RUN: %{python} %S/../CAS/Inputs/SwiftDepsExtractor.py %t/deps-3.json Library modulePath > %t/path-3

test/ScanDependencies/module_hash_macos.swift

@@ -0,0 +1,47 @@
+// REQUIRES: OS=macosx, objc_interop
+// RUN: %empty-directory(%t)
+// RUN: split-file %s %t
+
+/// Different version should not match.
+// RUN: %target-swift-frontend -target %module-target-triple -scan-dependencies -module-name Test %t/main.swift -module-cache-path %t/clang-module-cache \
+// RUN:   -disable-implicit-string-processing-module-import -disable-implicit-concurrency-module-import -O \
+// RUN:   -o %t/deps-now.json -I %t/include
+// RUN: %target-swift-frontend -target %module-target-future -scan-dependencies -module-name Test %t/main.swift -module-cache-path %t/clang-module-cache \
+// RUN:   -disable-implicit-string-processing-module-import -disable-implicit-concurrency-module-import -O \
+// RUN:   -o %t/deps-future.json -I %t/include
+// RUN: %{python} %S/../CAS/Inputs/SwiftDepsExtractor.py %t/deps-now.json Library modulePath > %t/path-now
+// RUN: %{python} %S/../CAS/Inputs/SwiftDepsExtractor.py %t/deps-future.json Library modulePath > %t/path-future
+// RUN: not diff %t/path-now %t/path-future
+
+/// Application extension should not match.
+// RUN: %target-swift-frontend -scan-dependencies -module-name Test %t/main.swift -module-cache-path %t/clang-module-cache \
+// RUN:   -disable-implicit-string-processing-module-import -disable-implicit-concurrency-module-import -O \
+// RUN:   -o %t/deps.json -I %t/include
+// RUN: %target-swift-frontend -scan-dependencies -module-name Test %t/main.swift -module-cache-path %t/clang-module-cache \
+// RUN:   -disable-implicit-string-processing-module-import -disable-implicit-concurrency-module-import -O \
+// RUN:   -o %t/deps-ae.json -I %t/include -application-extension
+// RUN: %{python} %S/../CAS/Inputs/SwiftDepsExtractor.py %t/deps.json Library modulePath > %t/path
+// RUN: %{python} %S/../CAS/Inputs/SwiftDepsExtractor.py %t/deps-ae.json Library modulePath > %t/path-ae
+// RUN: not diff %t/path %t/path-ae
+
+//--- main.swift
+import Library
+
+//--- include/Library.swiftinterface
+// swift-interface-format-version: 1.0
+// swift-module-flags: -module-name Library -O -disable-implicit-string-processing-module-import -disable-implicit-concurrency-module-import -user-module-version 1.0
+import Swift
+@_exported import A
+@inlinable
+public func test() {
+    foo()
+}
+
+//--- include/a.h
+void foo(void);
+
+//--- include/module.modulemap
+module A {
+  header "a.h"
+  export *
+}