Change strategy for non-primaries

No more vacuous subconsumers. Output into active primary or everywhere.

Author: David Ungar

include/swift/AST/DiagnosticConsumer.h

@@ -174,9 +174,10 @@ class FileSpecificDiagnosticConsumer : public DiagnosticConsumer {
     /// diagnostics that are not in any of the other consumers' files.
     std::string inputFileName;
 
-    /// The consumer (if any) for diagnostics associated with the inputFileName.
-    /// A null pointer for the DiagnosticConsumer means that diagnostics for
-    /// this file should not be emitted.
+    /// The consumer for diagnostics associated with the inputFileName.
+    /// Should never be null, because diagnostics for non-primary files are
+    /// either emitted in the corresponding primary file's .dia or are
+    /// emitted to every .dia.
     std::unique_ptr<DiagnosticConsumer> consumer;
 
     // Has this subconsumer ever handled a diagnostic that is an error?
@@ -196,8 +197,6 @@ class FileSpecificDiagnosticConsumer : public DiagnosticConsumer {
                           ArrayRef<DiagnosticArgument> FormatArgs,
                           const DiagnosticInfo &Info,
                           const SourceLoc defaultDiagnosticLoc) {
-      if (!getConsumer())
-        return;
       hasAnErrorBeenConsumed |= Kind == DiagnosticKind::Error;
       getConsumer()->handleDiagnostic(SM, Loc, Kind, FormatString, FormatArgs,
                                       Info, defaultDiagnosticLoc);

lib/AST/DiagnosticConsumer.cpp

@@ -186,6 +186,7 @@ Optional<FileSpecificDiagnosticConsumer::Subconsumer *>
 FileSpecificDiagnosticConsumer::findSubconsumer(
     SourceManager &SM, SourceLoc loc, DiagnosticKind Kind,
     SourceLoc defaultDiagnosticLoc) {
+  // Ensure that a note goes to the same place as the preceeding non-note.
   switch (Kind) {
   case DiagnosticKind::Error:
   case DiagnosticKind::Warning:
@@ -203,19 +204,13 @@ Optional<FileSpecificDiagnosticConsumer::Subconsumer *>
 FileSpecificDiagnosticConsumer::findSubconsumerForNonNote(
     SourceManager &SM, const SourceLoc loc,
     const SourceLoc defaultDiagnosticLoc) {
-  const auto subconsumer = subconsumerForLocation(SM, loc);
-  if (!subconsumer)
-    return None; // No place to put it
-  if ((*subconsumer)->getConsumer())
+  if (auto subconsumer = subconsumerForLocation(SM, loc))
     return subconsumer; // A primary file with a .dia file
-  if (defaultDiagnosticLoc.isInvalid())
-    return None;
-  const auto currentPrimarySubconsumer =
-      subconsumerForLocation(SM, defaultDiagnosticLoc);
-  assert(currentPrimarySubconsumer &&
-         (*currentPrimarySubconsumer)->getConsumer() &&
-         "current primary must have a .dia file");
-  return currentPrimarySubconsumer;
+  // The diagnostic is located in a non-primary.
+  // Try to put it in the current primary file's .dia file.
+  if (defaultDiagnosticLoc.isValid())
+    return subconsumerForLocation(SM, defaultDiagnosticLoc);
+  return None;
 }
 
 bool FileSpecificDiagnosticConsumer::finishProcessing() {

lib/FrontendTool/FrontendTool.cpp

@@ -1539,24 +1539,12 @@ createDispatchingDiagnosticConsumerIfNeeded(
 
   inputsAndOutputs.forEachInputProducingSupplementaryOutput(
       [&](const InputFile &input) -> bool {
-        if (auto consumer = maybeCreateConsumerForDiagnosticsFrom(input))
+        if (auto consumer = maybeCreateConsumerForDiagnosticsFrom(input)) {
+          assert(consumer && "Consumer should always be non-null");
           subconsumers.emplace_back(input.file(), std::move(consumer));
+        }
         return false;
       });
-  // For batch mode, the compiler must swallow diagnostics pertaining to
-  // non-primary files in order to avoid Xcode showing the same diagnostic
-  // multiple times. So, create a diagnostic "eater" for those non-primary
-  // files.
-  // To avoid introducing bugs into WMO or single-file modes, test for multiple
-  // primaries.
-  if (inputsAndOutputs.hasMultiplePrimaryInputs()) {
-    inputsAndOutputs.forEachNonPrimaryInput(
-        [&](const InputFile &input) -> bool {
-          subconsumers.emplace_back(input.file(), nullptr);
-          return false;
-        });
-  }
-
   return FileSpecificDiagnosticConsumer::consolidateSubconsumers(subconsumers);
 }