[ParseableInterface] Fix failing to build a module when the importing file has errors.

lib/Frontend/ParseableInterfaceSupport.cpp

@@ -452,7 +452,7 @@ bool ParseableInterfaceModuleLoader::buildSwiftModuleFromSwiftInterface(
       return;
     }
 
-    SubError = Diags.hadAnyError();
+    SubError = SubInstance.getDiags().hadAnyError();
   });
   return !RunSuccess || SubError;
 }

test/ParseableInterface/ModuleCache/module-cache-errors-in-importing-file.swift

@@ -0,0 +1,23 @@
+// RUN: %empty-directory(%t)
+// RUN: %empty-directory(%t/modulecache)
+//
+// Setup builds a parseable interface for a module SomeModule (built from some-module.swift).
+// This test checks we still build and load its corresponding .swiftmodule when the file that imports it contains an error prior to the import statement.
+
+// Setup phase 1: Write the input file.
+//
+// RUN: echo 'public func SomeFunc() -> Int { return 42; }' >>%t/some-module.swift
+
+// Setup phase 2: build the module.
+//
+// RUN: %target-swift-frontend -I %t -emit-parseable-module-interface-path %t/SomeModule.swiftinterface -module-name SomeModule %t/some-module.swift -emit-module -o /dev/null
+
+// Actual test: compile and verify the import succeeds (i.e. we only report the error in this file)
+//
+// RUN: %target-swift-frontend -typecheck -verify -I %t -module-cache-path %t/modulecache -enable-parseable-module-interface %s
+
+unresolved // expected-error {{use of unresolved identifier 'unresolved'}}
+
+import SomeModule
+
+print(SomeFunc())

test/SourceKit/CodeComplete/Inputs/parseable-interface/MyPoint.swift

@@ -0,0 +1,13 @@
+public struct MyPoint {
+	public let x: Double
+	public let y: Double
+
+	public init(x: Double, y: Double) {
+		self.x = x
+		self.y = y
+	}
+
+	public var magnitudeSquared: Double {
+		return x*x + y*y
+	}
+}

test/SourceKit/CodeComplete/Inputs/parseable-interface/MyPointExtensions.swift

@@ -0,0 +1,7 @@
+import MyPoint
+
+public extension MyPoint {
+	var magnitude: Double {
+		return magnitudeSquared.squareRoot()
+	}
+}

test/SourceKit/CodeComplete/complete_swiftinterface.swift

@@ -0,0 +1,28 @@
+// RUN: %empty-directory(%t)
+// RUN: %empty-directory(%t/modulecache)
+
+// 1) Build .swiftinterface files for MyPoint and MyExtensions
+// RUN: %target-swift-frontend -emit-parseable-module-interface-path %t/MyPoint.swiftinterface -module-name MyPoint -emit-module -o /dev/null %S/Inputs/parseable-interface/MyPoint.swift
+// RUN: %target-swift-frontend -emit-parseable-module-interface-path %t/MyPointExtensions.swiftinterface -module-name MyPointExtensions -emit-module -o /dev/null -enable-parseable-module-interface -module-cache-path %t/modulecache -I %t %S/Inputs/parseable-interface/MyPointExtensions.swift
+
+// 2) Check completion with a warm module cache from above
+// RUN: %swift-ide-test_plain -code-completion -code-completion-token=MEMBER -source-filename %s -I %t -module-cache-path %t/modulecache | %FileCheck %s
+
+// 3) Check completion with a cold module cache
+// RUN: %empty-directory(%t/modulecache)
+// RUN: %swift-ide-test_plain -code-completion -code-completion-token=MEMBER -source-filename %s -I %t -module-cache-path %t/modulecache | %FileCheck %s
+
+import MyPoint
+import MyPointExtensions
+
+let x = MyPoint(x: 1, y: 10.5)
+
+print(x.#^MEMBER^#)
+
+// CHECK: Begin completions, 5 items
+// CHECK: Keyword[self]/CurrNominal:          self[#MyPoint#]; name=self
+// CHECK: Decl[InstanceVar]/CurrNominal:      x[#Double#]; name=x
+// CHECK: Decl[InstanceVar]/CurrNominal:      y[#Double#]; name=y
+// CHECK: Decl[InstanceVar]/CurrNominal:      magnitudeSquared[#Double#]; name=magnitudeSquared
+// CHECK: Decl[InstanceVar]/CurrNominal:      magnitude[#Double#]; name=magnitude
+// CHECK: End completions

tools/swift-ide-test/swift-ide-test.cpp

@@ -258,6 +258,12 @@ static llvm::cl::opt<std::string>
 ModuleCachePath("module-cache-path", llvm::cl::desc("Clang module cache path"),
                 llvm::cl::cat(Category));
 
+static llvm::cl::opt<bool>
+EnableParseableModuleInterface("enable-parseable-module-interface",
+           llvm::cl::desc("Enable loading .swiftinterface files when available"),
+           llvm::cl::cat(Category),
+           llvm::cl::init(true));
+
 static llvm::cl::opt<std::string>
 PCHOutputDir("pch-output-dir",
              llvm::cl::desc("place autogenerated PCH files in this directory"),
@@ -3127,6 +3133,8 @@ int main(int argc, char *argv[]) {
         InitInvok.getLangOptions().EffectiveLanguageVersion = actual.getValue();
     }
   }
+  InitInvok.getFrontendOptions().EnableParseableModuleInterface =
+    options::EnableParseableModuleInterface;
   InitInvok.getClangImporterOptions().ModuleCachePath =
     options::ModuleCachePath;
   InitInvok.getClangImporterOptions().PrecompiledHeaderOutputDir =