Fix fingerprints in unit tests of driver.

Author: David Ungar

include/swift/Basic/Fingerprint.h

@@ -76,6 +76,10 @@ class Fingerprint final {
   /// Strings that violate this invariant will return a null optional.
   static llvm::Optional<Fingerprint> fromString(llvm::StringRef value);
 
+  /// For mocking only:
+  /// Aborts if unconvertible, returns None for an empty string.
+  static llvm::Optional<Fingerprint> mockFromString(llvm::StringRef value);
+
  /// Creates a fingerprint value by consuming the given \c MD5Result from LLVM.
   explicit Fingerprint(llvm::MD5::MD5Result &&MD5Value)
       : core{MD5Value.words()} {}

lib/Basic/Fingerprint.cpp

@@ -48,6 +48,24 @@ Optional<Fingerprint> Fingerprint::fromString(StringRef value) {
   return fp;
 }
 
+Optional<Fingerprint> Fingerprint::mockFromString(llvm::StringRef value) {
+  auto contents = value.str();
+  const auto n = value.size();
+  if (n == 0 || n > Fingerprint::DIGEST_LENGTH)
+    return None;
+  // Insert at start so that "1" and "10" are distinct
+  contents.insert(0, Fingerprint::DIGEST_LENGTH - n, '0');
+  auto fingerprint = fromString(contents);
+    if (!fingerprint) {
+    llvm::errs() << "unconvertable fingerprint from switdeps ':"
+                 << contents << "'\n";
+    abort();
+  }
+  return fingerprint;
+}
+
+
+
 llvm::SmallString<Fingerprint::DIGEST_LENGTH> Fingerprint::getRawValue() const {
   llvm::SmallString<Fingerprint::DIGEST_LENGTH> Str;
   llvm::raw_svector_ostream Res(Str);

unittests/Driver/MockingFineGrainedDependencyGraphs.cpp

@@ -42,17 +42,9 @@ mocking_fine_grained_dependency_graphs::getChangesForSimulatedLoad(
     const bool hadCompilationError) {
   auto swiftDeps =
     cmd->getOutput().getAdditionalOutputForType(file_types::TY_SwiftDeps).str();
-  assert(!swiftDeps.empty());
-  // Insert at start so that "1" and "10" are distinct
-  swiftDeps.insert(0, Fingerprint::DIGEST_LENGTH - swiftDeps.size(), '0');
-  auto swiftDepsFingerprint = Fingerprint::fromString(swiftDeps);
-  if (!swiftDepsFingerprint) {
-    llvm::errs() << "unconvertable fingerprint from switdeps ':"
-                 << swiftDeps << "'\n";
-    abort();
-  }
-  auto interfaceHash =
-    interfaceHashIfNonEmpty.getValueOr(swiftDepsFingerprint.getValue());
+  auto swiftDepsFingerprint =
+    Fingerprint::mockFromString(swiftDeps).getValue();
+  auto interfaceHash = interfaceHashIfNonEmpty.getValueOr(swiftDepsFingerprint);
 
   SourceManager sm;
   DiagnosticEngine diags(sm);

unittests/Driver/UnitTestSourceFileDepGraphFactory.cpp

@@ -54,10 +54,8 @@ void UnitTestSourceFileDepGraphFactory::addADefinedDecl(StringRef s,
   if (!key)
     return;
   auto fingerprintString = s.split(fingerprintSeparator).second.str();
-  fingerprintString.resize(Fingerprint::DIGEST_LENGTH, 'X');
-  const Optional<Fingerprint> fingerprint = fingerprintString.empty()
-                                              ? Optional<Fingerprint>()
-                                              : Fingerprint::fromString(fingerprintString);
+  const Optional<Fingerprint> fingerprint =
+    Fingerprint::mockFromString(fingerprintString);
 
   AbstractSourceFileDepGraphFactory::addADefinedDecl(key.getValue(),
                                                      fingerprint);