[ASTPrinter] Fix printing inconsistent implementation-only imported in experimental mode

Make sure we print imports that are sometimes normal and sometimes
implemntation-only in the experimental SPI import mode.

rdar://89620638

Author: xymus

lib/Frontend/ModuleInterfaceSupport.cpp

@@ -197,12 +197,22 @@ static void printImports(raw_ostream &out,
   // imports and filter them later.
   llvm::SmallSet<ImportedModule, 4, ImportedModule::Order> ioiImportSet;
   if (Opts.PrintSPIs && Opts.ExperimentalSPIImports) {
-    allImportFilter |= ModuleDecl::ImportFilterKind::ImplementationOnly;
 
-    SmallVector<ImportedModule, 4> ioiImport;
-    M->getImportedModules(ioiImport,
+    SmallVector<ImportedModule, 4> ioiImports, allImports;
+    M->getImportedModules(ioiImports,
                           ModuleDecl::ImportFilterKind::ImplementationOnly);
-    ioiImportSet.insert(ioiImport.begin(), ioiImport.end());
+
+    // Only consider modules imported consistently as implementation-only.
+    M->getImportedModules(allImports,
+                          allImportFilter);
+    llvm::SmallSet<ImportedModule, 8, ImportedModule::Order> allImportSet;
+    allImportSet.insert(allImports.begin(), allImports.end());
+
+    for (auto import: ioiImports)
+      if (allImportSet.count(import) == 0)
+        ioiImportSet.insert(import);
+
+    allImportFilter |= ModuleDecl::ImportFilterKind::ImplementationOnly;
   }
 
   SmallVector<ImportedModule, 8> allImports;

test/SPI/Inputs/experimental_spi_imports_inconsistent.swift

@@ -0,0 +1 @@
+@_implementationOnly import InconsistentlyImported

test/SPI/experimental_spi_imports_swiftinterface.swift

@@ -7,16 +7,22 @@
 // RUN: %target-swift-frontend -emit-module %S/Inputs/ioi_helper.swift -module-name ExperimentalImported -emit-module-path %t/ExperimentalImported.swiftmodule -swift-version 5 -enable-library-evolution
 // RUN: %target-swift-frontend -emit-module %t/empty.swift -module-name IOIImported -emit-module-path %t/IOIImported.swiftmodule -swift-version 5 -enable-library-evolution
 // RUN: %target-swift-frontend -emit-module %t/empty.swift -module-name SPIImported -emit-module-path %t/SPIImported.swiftmodule -swift-version 5 -enable-library-evolution
+// RUN: %target-swift-frontend -emit-module %t/empty.swift -module-name InconsistentlyImported -emit-module-path %t/InconsistentlyImported.swiftmodule -swift-version 5 -enable-library-evolution
 
 /// Test the generated swiftinterface.
-// RUN: %target-swift-frontend -typecheck %s -emit-module-interface-path %t/main.swiftinterface -emit-private-module-interface-path %t/main.private.swiftinterface -enable-library-evolution -swift-version 5 -I %t -experimental-spi-imports
+// RUN: %target-swift-frontend -typecheck %s %S/Inputs/experimental_spi_imports_inconsistent.swift -emit-module-interface-path %t/main.swiftinterface -emit-private-module-interface-path %t/main.private.swiftinterface -enable-library-evolution -swift-version 5 -I %t -experimental-spi-imports
 // RUN: %FileCheck -check-prefix=CHECK-PUBLIC %s < %t/main.swiftinterface
 // RUN: %FileCheck -check-prefix=CHECK-PRIVATE %s < %t/main.private.swiftinterface
 
 @_spi(dummy) @_implementationOnly import ExperimentalImported
 // CHECK-PUBLIC-NOT: import ExperimentalImported
 // CHECK-PRIVATE: @_implementationOnly @_spi{{.*}} import ExperimentalImported
 
+// This is also imported as implementation-only via another source file.
+import InconsistentlyImported
+// CHECK-PUBLIC: {{^}}import InconsistentlyImported
+// CHECK-PRIVATE: {{^}}import InconsistentlyImported
+
 @_implementationOnly import IOIImported
 // CHECK-PUBLIC-NOT: IOIImported
 // CHECK-PRIVATE-NOT: IOIImported