[Driver] Disallow bridging headers with framework targets.

While this appears to work, it causes problems down the line -- it's a
brittle configuration for debugging, and PrintAsObjC currently doesn't
fail gracefully if you reference a bridging-header-only type in your
public interface.

We definitely want something like this to work some day, but don't have
time to fix it now. Filed <rdar://problem/17615898>.

Swift SVN r19762

Author: jrose-apple

include/swift/AST/DiagnosticsDriver.def

@@ -78,6 +78,9 @@ ERROR(error_unknown_file_type,driver,none,
 ERROR(error_invalid_arch,driver,none,
       "invalid target architecture '%0'", (StringRef))
 
+ERROR(error_framework_bridging_header,driver,none,
+      "using bridging headers with framework targets is unsupported", ())
+
 #ifndef DIAG_NO_UNDEF
 # if defined(DIAG)
 #  undef DIAG

lib/Driver/Driver.cpp

@@ -68,6 +68,13 @@ Driver::~Driver() {
   llvm::DeleteContainerSeconds(ToolChains);
 }
 
+static void validateArgs(DiagnosticEngine &diags, const ArgList &Args) {
+  if (Args.hasArgNoClaim(options::OPT_import_underlying_module) &&
+      Args.hasArgNoClaim(options::OPT_import_objc_header)) {
+    diags.diagnose({}, diag::error_framework_bridging_header);
+  }
+}
+
 std::unique_ptr<Compilation> Driver::buildCompilation(
     ArrayRef<const char *> Args) {
   llvm::PrettyStackTraceString CrashInfo("Compilation construction");
@@ -92,6 +99,8 @@ std::unique_ptr<Compilation> Driver::buildCompilation(
 
   const ToolChain &TC = getToolChain(*ArgList);
 
+  validateArgs(Diags, *TranslatedArgList);
+
   if (Diags.hadAnyError())
     return nullptr;
 

test/Driver/options.swift

@@ -51,3 +51,6 @@
 
 // RUN: %swift_driver -assert-config DisableReplacement -### | FileCheck -check-prefix=ASSERTCONFIG6 %s
 // ASSERTCONFIG6: -assert-config DisableReplacement
+
+// RUN: not %swift_driver -import-objc-header fake.h -import-underlying-module -c %s 2>&1 | FileCheck -check-prefix=FRAMEWORK_BRIDGING_HEADER %s
+// FRAMEWORK_BRIDGING_HEADER: error: using bridging headers with framework targets is unsupported