[ClangImporter] Handle diagnostics about cast types in macros

CHANGELOG.md

@@ -6,6 +6,7 @@ CHANGELOG
 
 | Contents               |
 | :--------------------- |
+| [Swift 5.0](#swift-50) |
 | [Swift 4.1](#swift-41) |
 | [Swift 4.0](#swift-40) |
 | [Swift 3.1](#swift-31) |
@@ -19,6 +20,16 @@ CHANGELOG
 
 </details>
 
+Swift 5.0
+---------
+
+* C macros containing casts are no longer imported to Swift if the type in the
+  cast is unavailable or deprecated, or produces some other diagnostic when
+  referenced. (These macros were already only imported under very limited
+  circumstances with very simple values, so this is unlikely to affect
+  real-world code.)
+
+
 Swift 4.1
 ---------
 

lib/ClangImporter/ImportMacro.cpp

@@ -21,6 +21,7 @@
 #include "clang/AST/Expr.h"
 #include "clang/Lex/MacroInfo.h"
 #include "clang/Lex/Preprocessor.h"
+#include "clang/Sema/DelayedDiagnostic.h"
 #include "clang/Sema/Sema.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/APSIntType.h"
 #include "swift/AST/ASTContext.h"
@@ -361,10 +362,16 @@ static ValueDecl *importMacro(ClangImporter::Implementation &impl,
       }
       auto identifierName = identifierInfo->getName();
       auto &identifier = impl.getClangASTContext().Idents.get(identifierName);
+
+      clang::sema::DelayedDiagnosticPool diagPool{
+          impl.getClangSema().DelayedDiagnostics.getCurrentPool()};
+      auto diagState = impl.getClangSema().DelayedDiagnostics.push(diagPool);
       auto parsedType = impl.getClangSema().getTypeName(identifier,
                                                         clang::SourceLocation(),
                                                         /*scope*/nullptr);
-      if (parsedType) {
+      impl.getClangSema().DelayedDiagnostics.popWithoutEmitting(diagState);
+
+      if (parsedType && diagPool.empty()) {
         castType = parsedType.get();
       } else {
         return nullptr;

test/ClangImporter/macros.swift

@@ -172,3 +172,9 @@ func testRecursion() {
   _ = RECURSION_IN_EXPR2 // expected-error {{use of unresolved identifier 'RECURSION_IN_EXPR2'}}
   _ = RECURSION_IN_EXPR3 // expected-error {{use of unresolved identifier 'RECURSION_IN_EXPR3'}}
 }
+
+func testNulls() {
+  let _: Int = UNAVAILABLE_ONE // expected-error {{use of unresolved identifier 'UNAVAILABLE_ONE'}}
+  let _: Int = DEPRECATED_ONE // expected-error {{use of unresolved identifier 'DEPRECATED_ONE'}}
+  let _: Int = OKAY_TYPED_ONE // expected-error {{cannot convert value of type 'okay_t' (aka 'UInt32') to specified type 'Int'}}
+}

test/Inputs/clang-importer-sdk/usr/include/macros.h

@@ -144,3 +144,12 @@
 
 #define RECURSION_WITH_EXPR3 RECURSION_WITH_EXPR3_HELPER + 1
 #define RECURSION_WITH_EXPR3_HELPER RECURSION_WITH_EXPR3 + 1
+
+
+// Casts with problematic types
+#define UNAVAILABLE_ONE ((unavailable_t)1)
+typedef unsigned unavailable_t __attribute__((unavailable));
+#define DEPRECATED_ONE ((deprecated_t)1)
+typedef unsigned deprecated_t __attribute__((deprecated));
+#define OKAY_TYPED_ONE ((okay_t)1)
+typedef unsigned okay_t;