[CodeCompletion] Explain why results aren't recommended

* Implement 'getDiagnosticSeverity()' and 'getDiagnosticMessage()' on
  'CodeCompletionResult'
* Differentiate 'RedundantImportIndirect' from 'RedundantImport'
* Make non-Sendable check respects '-warn-concurrency'

rdar://76129658

Author: rintaro

include/swift/AST/DiagnosticEngine.h

@@ -1116,6 +1116,8 @@ namespace swift {
     void emitTentativeDiagnostics();
 
   public:
+    DiagnosticKind declaredDiagnosticKindFor(const DiagID id);
+
     llvm::StringRef diagnosticStringFor(const DiagID id,
                                         bool printDiagnosticNames);
 
@@ -1313,6 +1315,26 @@ namespace swift {
     builder();
   }
 
+/// Temporary on-stack storage and unescaping for encoded diagnostic
+/// messages.
+class EncodedDiagnosticMessage {
+  llvm::SmallString<128> Buf;
+
+public:
+  /// \param S A string with an encoded message
+  EncodedDiagnosticMessage(StringRef S);
+
+  /// The unescaped message to display to the user.
+  const StringRef Message;
+};
+
+/// Returns a value that can be used to select between accessor kinds in
+/// diagnostics.
+///
+/// This is correlated with diag::availability_deprecated and others.
+std::pair<unsigned, DeclName>
+getAccessorKindAndNameForDiagnostics(const ValueDecl *D);
+
 } // end namespace swift
 
 #endif

include/swift/AST/DiagnosticsAll.def

@@ -20,6 +20,7 @@
 #define DIAG_NO_UNDEF
 
 #include "DiagnosticsCommon.def"
+#include "DiagnosticsIDE.def"
 #include "DiagnosticsParse.def"
 #include "DiagnosticsSema.def"
 #include "DiagnosticsClangImporter.def"

include/swift/AST/DiagnosticsIDE.def

@@ -0,0 +1,39 @@
+//===--- DiagnosticsIDE.def - Diagnostics Text ------------------*- C++ -*-===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2021 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+#define DEFINE_DIAGNOSTIC_MACROS
+#include "DefineDiagnosticMacros.h"
+
+//===----------------------------------------------------------------------===//
+
+ERROR(ide_async_in_nonasync_context, none,
+      "async %0 used in a context that does not support concurrency",
+      (DeclName))
+
+// NOTE: This is WARNING because this is emitted for cross actor references with
+// non-'Sendable' types. That is optionally ('-warn-concurrency') warning in
+// Swift 5.5.
+WARNING(ide_cross_actor_reference_swift5, none,
+        "actor-isolated %0 should only be referenced from inside the actor",
+        (DeclName))
+
+WARNING(ide_redundant_import, none,
+        "module %0 is already imported", (DeclName))
+
+// FIXME: Inform which other 'import' this module came from.
+NOTE(ide_redundant_import_indirect, none,
+     "module %0 is already imported via another module import", (DeclName))
+
+//===----------------------------------------------------------------------===//
+
+#define UNDEFINE_DIAGNOSTIC_MACROS
+#include "DefineDiagnosticMacros.h"

include/swift/AST/DiagnosticsIDE.h

@@ -0,0 +1,32 @@
+//===--- DiagnosticsIDE.h - Diagnostic Definitions --------------*- C++ -*-===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2021 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+//
+/// \file
+/// This file defines diagnostics used only in IDE.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef SWIFT_DIAGNOSTICSIDE_H
+#define SWIFT_DIAGNOSTICSIDE_H
+
+#include "swift/AST/DiagnosticsCommon.h"
+
+namespace swift {
+  namespace diag {
+  // Declare common diagnostics objects with their appropriate types.
+#define DIAG(KIND,ID,Options,Text,Signature) \
+    extern detail::DiagWithArguments<void Signature>::type ID;
+#include "DiagnosticsIDE.def"
+  }
+}
+
+#endif

include/swift/IDE/CodeCompletion.h

@@ -568,6 +568,14 @@ enum class CompletionKind {
   TypeAttrBeginning,
 };
 
+enum class CodeCompletionDiagnosticSeverity: uint8_t {
+  None,
+  Error,
+  Warning,
+  Remark,
+  Note,
+};
+
 /// A single code completion result.
 class CodeCompletionResult {
   friend class CodeCompletionResultBuilder;
@@ -607,6 +615,7 @@ class CodeCompletionResult {
   enum class NotRecommendedReason {
     None = 0,
     RedundantImport,
+    RedundantImportIndirect,
     Deprecated,
     InvalidAsyncContext,
     CrossActorReference,
@@ -638,6 +647,8 @@ class CodeCompletionResult {
   ArrayRef<StringRef> AssociatedUSRs;
   ArrayRef<std::pair<StringRef, StringRef>> DocWords;
   unsigned TypeDistance : 3;
+  unsigned DiagnosticSeverity: 3;
+  StringRef DiagnosticMessage;
 
 public:
   /// Constructs a \c Pattern, \c Keyword or \c BuiltinOperator result.
@@ -664,6 +675,7 @@ class CodeCompletionResult {
            getOperatorKind() != CodeCompletionOperatorKind::None);
     AssociatedKind = 0;
     IsSystem = 0;
+    DiagnosticSeverity = 0;
   }
 
   /// Constructs a \c Keyword result.
@@ -684,6 +696,7 @@ class CodeCompletionResult {
     assert(CompletionString);
     AssociatedKind = static_cast<unsigned>(Kind);
     IsSystem = 0;
+    DiagnosticSeverity = 0;
   }
 
   /// Constructs a \c Literal result.
@@ -701,6 +714,7 @@ class CodeCompletionResult {
         TypeDistance(TypeDistance) {
     AssociatedKind = static_cast<unsigned>(LiteralKind);
     IsSystem = 0;
+    DiagnosticSeverity = 0;
     assert(CompletionString);
   }
 
@@ -728,6 +742,7 @@ class CodeCompletionResult {
     assert(AssociatedDecl && "should have a decl");
     AssociatedKind = unsigned(getCodeCompletionDeclKind(AssociatedDecl));
     IsSystem = getDeclIsSystem(AssociatedDecl);
+    DiagnosticSeverity = 0;
     assert(CompletionString);
     if (isOperator())
       KnownOperatorKind =
@@ -743,20 +758,22 @@ class CodeCompletionResult {
                        CodeCompletionDeclKind DeclKind, bool IsSystem,
                        StringRef ModuleName, StringRef SourceFilePath,
                        CodeCompletionResult::NotRecommendedReason NotRecReason,
-                       StringRef BriefDocComment,
+                       CodeCompletionDiagnosticSeverity diagSeverity,
+                       StringRef DiagnosticMessage, StringRef BriefDocComment,
                        ArrayRef<StringRef> AssociatedUSRs,
                        ArrayRef<std::pair<StringRef, StringRef>> DocWords,
                        ExpectedTypeRelation TypeDistance,
                        CodeCompletionOperatorKind KnownOperatorKind)
       : Kind(ResultKind::Declaration),
         KnownOperatorKind(unsigned(KnownOperatorKind)),
-        SemanticContext(unsigned(SemanticContext)),
-        Flair(unsigned(Flair.toRaw())), NotRecommended(unsigned(NotRecReason)),
-        IsSystem(IsSystem), NumBytesToErase(NumBytesToErase),
-        CompletionString(CompletionString), ModuleName(ModuleName),
-        SourceFilePath(SourceFilePath), BriefDocComment(BriefDocComment),
-        AssociatedUSRs(AssociatedUSRs), DocWords(DocWords),
-        TypeDistance(TypeDistance) {
+        SemanticContext(unsigned(SemanticContext)), Flair(unsigned(Flair.toRaw())),
+        NotRecommended(unsigned(NotRecReason)), IsSystem(IsSystem),
+        NumBytesToErase(NumBytesToErase), CompletionString(CompletionString),
+        ModuleName(ModuleName), SourceFilePath(SourceFilePath),
+        BriefDocComment(BriefDocComment), AssociatedUSRs(AssociatedUSRs),
+        DocWords(DocWords), TypeDistance(TypeDistance),
+        DiagnosticSeverity(unsigned(diagSeverity)),
+        DiagnosticMessage(DiagnosticMessage) {
     AssociatedKind = static_cast<unsigned>(DeclKind);
     assert(CompletionString);
     assert(!isOperator() ||
@@ -859,6 +876,19 @@ class CodeCompletionResult {
     SourceFilePath = value;
   }
 
+  void setDiagnostics(CodeCompletionDiagnosticSeverity severity, StringRef message) {
+    DiagnosticSeverity = static_cast<unsigned>(severity);
+    DiagnosticMessage = message;
+  }
+
+  CodeCompletionDiagnosticSeverity getDiagnosticSeverity() const {
+    return static_cast<CodeCompletionDiagnosticSeverity>(DiagnosticSeverity);
+  }
+
+  StringRef getDiagnosticMessage() const {
+    return DiagnosticMessage;
+  }
+
   /// Returns the source file path where the associated decl was declared.
   /// Returns an empty string if the information is not available.
   StringRef getSourceFilePath() const {

include/swift/Parse/Lexer.h

@@ -448,7 +448,7 @@ class Lexer {
   /// the byte content.
   ///
   /// If a copy needs to be made, it will be allocated out of the provided
-  /// \p Buffer.
+  /// \p Buffer. If \p IndentToStrip is '~0U', the indent is auto-detected.
   static StringRef getEncodedStringSegment(StringRef Str,
                                            SmallVectorImpl<char> &Buffer,
                                            bool IsFirstSegment = false,

lib/AST/DiagnosticEngine.cpp

@@ -1244,6 +1244,10 @@ void DiagnosticEngine::emitDiagnostic(const Diagnostic &diagnostic) {
     emitDiagnostic(childNote);
 }
 
+DiagnosticKind DiagnosticEngine::declaredDiagnosticKindFor(const DiagID id) {
+  return storedDiagnosticInfos[(unsigned)id].kind;
+}
+
 llvm::StringRef
 DiagnosticEngine::diagnosticStringFor(const DiagID id,
                                       bool printDiagnosticNames) {
@@ -1322,3 +1326,24 @@ void DiagnosticEngine::onTentativeDiagnosticFlush(Diagnostic &diagnostic) {
     argument = DiagnosticArgument(StringRef(I->getKeyData()));
   }
 }
+
+EncodedDiagnosticMessage::EncodedDiagnosticMessage(StringRef S)
+    : Message(Lexer::getEncodedStringSegment(S, Buf, /*IsFirstSegment=*/true,
+                                             /*IsLastSegment=*/true,
+                                             /*IndentToStrip=*/~0U)) {}
+
+std::pair<unsigned, DeclName>
+swift::getAccessorKindAndNameForDiagnostics(const ValueDecl *D) {
+  // This should always be one more than the last AccessorKind supported in
+  // the diagnostics. If you need to change it, change the assertion below as
+  // well.
+  static const unsigned NOT_ACCESSOR_INDEX = 2;
+
+  if (auto *accessor = dyn_cast<AccessorDecl>(D)) {
+    DeclName Name = accessor->getStorage()->getName();
+    assert(accessor->isGetterOrSetter());
+    return {static_cast<unsigned>(accessor->getAccessorKind()), Name};
+  }
+
+  return {NOT_ACCESSOR_INDEX, D->getName()};
+}

lib/IDE/CMakeLists.txt

@@ -2,6 +2,7 @@
 add_swift_host_library(swiftIDE STATIC
   CodeCompletion.cpp
   CodeCompletionCache.cpp
+  CodeCompletionDiagnostics.cpp
   CodeCompletionResultPrinter.cpp
   CommentConversion.cpp
   CompletionInstance.cpp