Centralize and clean up setting of "used @preconcurrency" state.

Author: DougGregor

lib/Sema/TypeCheckConcurrency.cpp

@@ -721,10 +721,13 @@ DiagnosticBehavior SendableCheckContext::diagnosticBehavior(
   auto import = findImportFor(nominal, fromDC);
 
   // When the type is explicitly non-Sendable...
+  auto sourceFile = fromDC->getParentSourceFile();
   if (isExplicitlyNonSendable) {
     // @preconcurrency imports downgrade the diagnostic to a warning in Swift 6,
     if (import && import->options.contains(ImportFlags::Preconcurrency)) {
-      // FIXME: Note that this @preconcurrency import was "used".
+      if (sourceFile)
+        sourceFile->setImportUsedPreconcurrency(*import);
+
       return DiagnosticBehavior::Warning;
     }
 
@@ -736,7 +739,9 @@ DiagnosticBehavior SendableCheckContext::diagnosticBehavior(
   // @preconcurrency suppresses the diagnostic in Swift 5.x, and
   // downgrades it to a warning in Swift 6 and later.
   if (import && import->options.contains(ImportFlags::Preconcurrency)) {
-    // FIXME: Note that this @preconcurrency import was "used".
+    if (sourceFile)
+      sourceFile->setImportUsedPreconcurrency(*import);
+
     return nominalModule->getASTContext().LangOpts.isSwiftVersionAtLeast(6)
         ? DiagnosticBehavior::Warning
         : DiagnosticBehavior::Ignore;
@@ -774,14 +779,6 @@ static bool diagnoseSingleNonSendableType(
 
   bool wasSuppressed = diagnose(type, behavior);
 
-  // If this type was imported from another module, try to find the
-  // corresponding import.
-  Optional<AttributedImport<swift::ImportedModule>> import;
-  SourceFile *sourceFile = fromContext.fromDC->getParentSourceFile();
-  if (nominal && nominal->getParentModule() != module) {
-    import = findImportFor(nominal, fromContext.fromDC);
-  }
-
   if (behavior == DiagnosticBehavior::Ignore || wasSuppressed) {
     // Don't emit any other diagnostics.
   } else if (type->is<FunctionType>()) {
@@ -805,6 +802,14 @@ static bool diagnoseSingleNonSendableType(
         diag::non_sendable_nominal, nominal->getDescriptiveKind(),
         nominal->getName());
 
+    // This type was imported from another module; try to find the
+    // corresponding import.
+    Optional<AttributedImport<swift::ImportedModule>> import;
+    SourceFile *sourceFile = fromContext.fromDC->getParentSourceFile();
+    if (sourceFile) {
+      import = findImportFor(nominal, fromContext.fromDC);
+    }
+
     // If we found the import that makes this nominal type visible, remark
     // that it can be @preconcurrency import.
     // Only emit this remark once per source file, because it can happen a
@@ -823,14 +828,6 @@ static bool diagnoseSingleNonSendableType(
     }
   }
 
-  // If we found an import that makes this nominal type visible, and that
-  // was a @preconcurrency import, note that we have made use of the
-  // attribute.
-  if (import && import->options.contains(ImportFlags::Preconcurrency) &&
-      sourceFile) {
-    sourceFile->setImportUsedPreconcurrency(*import);
-  }
-
   return behavior == DiagnosticBehavior::Unspecified && !wasSuppressed;
 }