Fix and test for extension body

Author: David Ungar

include/swift/AST/DeclContext.h

@@ -814,7 +814,7 @@ class IterableDeclContext {
   /// available.
   Optional<std::string> getBodyFingerprint() const;
 
-  bool areDependenciesUsingTokenHashesForTypeBodies() const;
+  bool areTokensHashedForThisBodyInsteadOfInterfaceHash() const;
 
 private:
   /// Add a member to the list for iteration purposes, but do not notify the

lib/AST/DeclContext.cpp

@@ -918,7 +918,13 @@ Optional<std::string> IterableDeclContext::getBodyFingerprint() const {
       .fingerprint;
 }
 
-bool IterableDeclContext::areDependenciesUsingTokenHashesForTypeBodies() const {
+bool IterableDeclContext::areTokensHashedForThisBodyInsteadOfInterfaceHash()
+    const {
+  // Do not keep separate hashes for extension bodies because the dependencies
+  // can miss the addition of a member in an extension because there is nothing
+  // corresponding to the fingerprinted nominal dependency node.
+  if (isa<ExtensionDecl>(this))
+    return false;
   return getASTContext().LangOpts.EnableTypeFingerprints;
 }
 

lib/AST/FrontendSourceFileDepGraphFactory.cpp

@@ -721,8 +721,7 @@ FrontendSourceFileDepGraphFactory::getInterfaceHash(SourceFile *SF) {
   return interfaceHash.str().str();
 }
 
-/// At present, only nominals, protocols, and extensions have (body)
-/// fingerprints
+/// At present, only \c NominalTypeDecls have (body) fingerprints
 Optional<std::string> FrontendSourceFileDepGraphFactory::getFingerprintIfAny(
     std::pair<const NominalTypeDecl *, const ValueDecl *>) {
   return None;

lib/Parse/ParseDecl.cpp

@@ -4517,13 +4517,13 @@ Parser::parseDeclList(SourceLoc LBLoc, SourceLoc &RBLoc, Diag<> ErrorDiag,
                       bool &hadError) {
 
   // Record the curly braces but nothing inside.
-  if (IDC->areDependenciesUsingTokenHashesForTypeBodies()) {
+  if (IDC->areTokensHashedForThisBodyInsteadOfInterfaceHash()) {
     recordTokenHash("{");
     recordTokenHash("}");
   }
   llvm::MD5 tokenHashForThisDeclList;
   llvm::SaveAndRestore<NullablePtr<llvm::MD5>> T(
-      CurrentTokenHash, IDC->areDependenciesUsingTokenHashesForTypeBodies()
+      CurrentTokenHash, IDC->areTokensHashedForThisBodyInsteadOfInterfaceHash()
                             ? &tokenHashForThisDeclList
                             : CurrentTokenHash);
 

test/Frontend/Fingerprints/Inputs/extension-adds-member/definesAB-after.swift

@@ -0,0 +1,9 @@
+struct A {
+}
+struct B {
+}
+extension A {
+  var x: Int {17}
+}
+extension B {
+}

test/Frontend/Fingerprints/Inputs/extension-adds-member/definesAB-before.swift

@@ -0,0 +1,8 @@
+struct A {
+}
+struct B {
+}
+extension A {
+}
+extension B {
+}

test/Frontend/Fingerprints/Inputs/extension-adds-member/main.swift

@@ -0,0 +1 @@
+

test/Frontend/Fingerprints/Inputs/extension-adds-member/ofm.json

@@ -0,0 +1,22 @@
+{
+  "main.swift": {
+    "object": "./main.o",
+    "swift-dependencies": "./main.swiftdeps"
+  },
+  "definesAB.swift": {
+    "object": "./definesAB.o",
+    "swift-dependencies": "./definesAB.swiftdeps"
+  },
+  "usesA.swift": {
+    "object": "./usesA.o",
+    "swift-dependencies": "./usesA.swiftdeps"
+  },
+  "usesB.swift": {
+    "object": "./usesB.o",
+    "swift-dependencies": "./usesB.swiftdeps"
+  },
+  "": {
+    "swift-dependencies": "./main~buildrecord.swiftdeps"
+  }
+}
+

test/Frontend/Fingerprints/Inputs/extension-adds-member/usesA.swift

@@ -0,0 +1 @@
+let a = A()

test/Frontend/Fingerprints/Inputs/extension-adds-member/usesB.swift

@@ -0,0 +1 @@
+let b = B()