[Bridging PCH] Handle mixed PCH + implicit bridging header imports.

This happens fairly regularly in unit testing scenarios.

Author: graydon

lib/ClangImporter/SwiftLookupTable.cpp

@@ -322,7 +322,8 @@ clang::NamedDecl *SwiftLookupTable::resolveContext(StringRef unresolvedName) {
 }
 
 void SwiftLookupTable::addCategory(clang::ObjCCategoryDecl *category) {
-  assert(!Reader && "Cannot modify a lookup table stored on disk");
+  // Force deserialization to occur before appending.
+  (void) categories();
 
   // Add the category.
   Categories.push_back(category);
@@ -467,8 +468,6 @@ bool SwiftLookupTable::addLocalEntry(SingleEntry newEntry,
 void SwiftLookupTable::addEntry(DeclName name, SingleEntry newEntry,
                                 EffectiveClangContext effectiveContext,
                                 const clang::Preprocessor *PP) {
-  assert(!Reader && "Cannot modify a lookup table stored on disk");
-
   // Translate the context.
   auto contextOpt = translateContext(effectiveContext);
   if (!contextOpt) {
@@ -484,6 +483,9 @@ void SwiftLookupTable::addEntry(DeclName name, SingleEntry newEntry,
     return;
   }
 
+  // Populate cache from reader if necessary.
+  findOrCreate(name.getBaseName().str());
+
   auto context = *contextOpt;
 
   // If this is a global imported as a member, record is as such.

test/ClangImporter/Inputs/app-bridging-header-to-pch.h

@@ -0,0 +1,3 @@
+static inline int app_function(int x) {
+  return x + 27;
+}

test/ClangImporter/Inputs/app-that-uses-pch-bridging-header.swift

@@ -0,0 +1,6 @@
+import Foundation
+
+public func AppFunc() -> Int32 {
+  return app_function(10)
+}
+

test/ClangImporter/Inputs/chained-unit-test-bridging-header-to-pch.h

@@ -0,0 +1,5 @@
+#import "app-bridging-header-to-pch.h"
+
+static inline int unit_test_function(int x) {
+  return x + 28;
+}

test/ClangImporter/Inputs/unit-test-bridging-header-to-pch.h

@@ -0,0 +1,3 @@
+static inline int unit_test_function(int x) {
+  return x + 28;
+}

test/ClangImporter/pch-bridging-header-unittest-ok.swift

@@ -0,0 +1,21 @@
+// REQUIRES: objc_interop
+// RUN: rm -rf %t && mkdir -p %t/tmp
+// RUN: %target-swiftc_driver -emit-module -import-objc-header %S/Inputs/app-bridging-header-to-pch.h -module-name App -emit-module-path %t/App.swiftmodule %S/Inputs/app-that-uses-pch-bridging-header.swift
+// RUN: llvm-bcanalyzer -dump %t/App.swiftmodule | %FileCheck %s
+// CHECK: IMPORTED_HEADER{{.*}}Inputs/app-bridging-header-to-pch.h
+
+// Should get no warnings when we PCH-in the chained unit-test bridging header (thereby suppressing implicit import)
+// RUN: %target-swiftc_driver -D UNIT_TESTS -typecheck -Xfrontend -verify -import-objc-header %S/Inputs/chained-unit-test-bridging-header-to-pch.h  -I %S/Inputs -I %t %s
+
+// Should get no warnings when we PCH-in the app bridging header (thereby suppressing implicit import)
+// RUN: %target-swiftc_driver -typecheck -Xfrontend -verify -import-objc-header %S/Inputs/app-bridging-header-to-pch.h -I %t %s
+
+import App
+
+func test_all() {
+#if UNIT_TESTS
+  let _ = unit_test_function(AppFunc())
+#else
+  let _ = app_function(AppFunc())
+#endif
+}

test/ClangImporter/pch-bridging-header-unittest-warn.swift

@@ -0,0 +1,21 @@
+// REQUIRES: objc_interop
+// RUN: rm -rf %t && mkdir -p %t/tmp
+// RUN: %target-swiftc_driver -emit-module -import-objc-header %S/Inputs/app-bridging-header-to-pch.h -module-name App -emit-module-path %t/App.swiftmodule %S/Inputs/app-that-uses-pch-bridging-header.swift
+// RUN: llvm-bcanalyzer -dump %t/App.swiftmodule | %FileCheck %s
+// CHECK: IMPORTED_HEADER{{.*}}Inputs/app-bridging-header-to-pch.h
+
+// Should get a warning when we PCH-in the unit test header and then implicitly import the app header.
+// RUN: %target-swiftc_driver -D UNIT_TESTS -typecheck -Xfrontend -verify -import-objc-header %S/Inputs/unit-test-bridging-header-to-pch.h -I %t %s
+
+// Should get a warning when skip the unit test header entirely and implicitly import the app header.
+// RUN: %target-swiftc_driver -typecheck -Xfrontend -verify -I %t %s
+
+import App // expected-warning{{implicit import of bridging header 'app-bridging-header-to-pch.h' via module 'App' is deprecated and will be removed in a later version of Swift}}
+
+func test_all() {
+#if UNIT_TESTS
+  let _ = unit_test_function(AppFunc())
+#else
+  let _ = app_function(AppFunc())
+#endif
+}