Implement #warning and #error (#14048)

* Implement #warning and #error

* Fix #warning/#error in switch statements

* Fix AST printing for #warning/#error

* Add to test case

* Add extra handling to ParseDeclPoundDiagnostic

* fix dumping

* Consume the right paren even in the failure case

* Diagnose extra tokens on the same line after a diagnostic directive

include/swift/AST/Attr.h

@@ -295,6 +295,7 @@ class DeclAttribute : public AttributeBase {
 
     // Cannot have any attributes.
     OnMissingMember = 0,
+    OnPoundDiagnostic = 0,
 
     // More coarse-grained aggregations for use in Attr.def.
     OnOperator = OnInfixOperator|OnPrefixOperator|OnPostfixOperator,

include/swift/AST/Decl.h

@@ -23,6 +23,7 @@
 #include "swift/AST/ClangNode.h"
 #include "swift/AST/ConcreteDeclRef.h"
 #include "swift/AST/DefaultArgumentKind.h"
+#include "swift/AST/DiagnosticConsumer.h"
 #include "swift/AST/GenericParamKey.h"
 #include "swift/AST/IfConfigClause.h"
 #include "swift/AST/LayoutConstraint.h"
@@ -107,6 +108,7 @@ enum class DescriptiveDeclKind : uint8_t {
   EnumCase,
   TopLevelCode,
   IfConfig,
+  PoundDiagnostic,
   PatternBinding,
   Var,
   Param,
@@ -591,6 +593,14 @@ class alignas(1 << DeclAlignInBits) Decl {
     HadMissingEnd : 1
   );
 
+  SWIFT_INLINE_BITFIELD(PoundDiagnosticDecl, Decl, 1+1,
+    /// `true` if the diagnostic is an error, `false` if it's a warning.
+    IsError : 1,
+
+    /// Whether this diagnostic has already been emitted.
+    HasBeenEmitted : 1
+  );
+
   SWIFT_INLINE_BITFIELD(MissingMemberDecl, Decl, 1+2,
     NumberOfFieldOffsetVectorEntries : 1,
     NumberOfVTableEntries : 2
@@ -2059,6 +2069,52 @@ class IfConfigDecl : public Decl {
   }
 };
 
+class StringLiteralExpr;
+
+class PoundDiagnosticDecl : public Decl {
+  SourceLoc StartLoc;
+  SourceLoc EndLoc;
+  StringLiteralExpr *Message;
+
+public:
+  PoundDiagnosticDecl(DeclContext *Parent, bool IsError, SourceLoc StartLoc,
+                      SourceLoc EndLoc, StringLiteralExpr *Message)
+    : Decl(DeclKind::PoundDiagnostic, Parent), StartLoc(StartLoc),
+      EndLoc(EndLoc), Message(Message) {
+      Bits.PoundDiagnosticDecl.IsError = IsError;
+      Bits.PoundDiagnosticDecl.HasBeenEmitted = false; 
+    }
+
+  DiagnosticKind getKind() {
+    return isError() ? DiagnosticKind::Error : DiagnosticKind::Warning;
+  }
+
+  StringLiteralExpr *getMessage() { return Message; }
+
+  bool isError() {
+    return Bits.PoundDiagnosticDecl.IsError;
+  }
+
+  bool hasBeenEmitted() {
+    return Bits.PoundDiagnosticDecl.HasBeenEmitted;
+  }
+
+  void markEmitted() {
+    Bits.PoundDiagnosticDecl.HasBeenEmitted = true;
+  }
+
+  SourceLoc getEndLoc() const { return EndLoc; };
+  SourceLoc getLoc() const { return StartLoc; }
+
+  SourceRange getSourceRange() const {
+    return SourceRange(StartLoc, EndLoc);
+  }
+
+  static bool classof(const Decl *D) {
+    return D->getKind() == DeclKind::PoundDiagnostic;
+  }
+};
+
 /// ValueDecl - All named decls that are values in the language.  These can
 /// have a type, etc.
 class ValueDecl : public Decl {

include/swift/AST/DeclNodes.def

@@ -171,6 +171,7 @@ ITERABLE_GENERIC_DECL(Extension, Decl)
 CONTEXT_DECL(TopLevelCode, Decl)
 DECL(Import, Decl)
 DECL(IfConfig, Decl)
+DECL(PoundDiagnostic, Decl)
 DECL(PrecedenceGroup, Decl)
 DECL(MissingMember, Decl)
 DECL(PatternBinding, Decl)

include/swift/AST/DiagnosticsParse.def

@@ -68,6 +68,17 @@ ERROR(extra_tokens_conditional_compilation_directive,none,
 ERROR(unexpected_rbrace_in_conditional_compilation_block,none,
       "unexpected '}' in conditional compilation block", ())
 
+ERROR(pound_diagnostic_expected_string,none,
+      "expected string literal in %select{#warning|#error}0 directive",(bool))
+ERROR(pound_diagnostic_expected,none,
+      "expected '%0' in %select{#warning|#error}1 directive",(StringRef,bool))
+ERROR(pound_diagnostic_expected_parens,none,
+      "%select{#warning|#error}0 directive requires parentheses",(bool))
+ERROR(pound_diagnostic_interpolation,none,
+      "string interpolation is not allowed in %select{#warning|#error}0 directives",(bool))
+ERROR(extra_tokens_pound_diagnostic_directive,none,
+      "extra tokens following %select{#warning|#error}0 directive", (bool))
+
 ERROR(sourceLocation_expected,none,
       "expected '%0' in #sourceLocation directive", (StringRef))
 

include/swift/AST/DiagnosticsSema.def

@@ -1007,6 +1007,9 @@ ERROR(enum_element_not_materializable,none,
 ERROR(missing_initializer_def,PointsToFirstBadToken,
       "initializer requires a body", ())
 
+WARNING(pound_warning, none, "%0", (StringRef))
+ERROR(pound_error, none, "%0", (StringRef))
+
 // Attributes
 
 ERROR(operator_not_func,none,

include/swift/AST/Stmt.h

@@ -955,8 +955,8 @@ class SwitchStmt final : public LabeledStmt,
   }
 
 private:
-  struct AsCaseStmtWithSkippingIfConfig {
-    AsCaseStmtWithSkippingIfConfig() {}
+  struct AsCaseStmtWithSkippingNonCaseStmts {
+    AsCaseStmtWithSkippingNonCaseStmts() {}
     Optional<CaseStmt*> operator()(const ASTNode &N) const {
       if (auto *CS = llvm::dyn_cast_or_null<CaseStmt>(N.dyn_cast<Stmt*>()))
         return CS;
@@ -966,11 +966,11 @@ class SwitchStmt final : public LabeledStmt,
 
 public:
   using AsCaseStmtRange = OptionalTransformRange<ArrayRef<ASTNode>,
-                                                AsCaseStmtWithSkippingIfConfig>;
+                            AsCaseStmtWithSkippingNonCaseStmts>;
 
   /// Get the list of case clauses.
   AsCaseStmtRange getCases() const {
-    return AsCaseStmtRange(getRawCases(), AsCaseStmtWithSkippingIfConfig());
+    return AsCaseStmtRange(getRawCases(), AsCaseStmtWithSkippingNonCaseStmts());
   }
 
   static bool classof(const Stmt *S) {

include/swift/AST/TypeMemberVisitor.h

@@ -48,6 +48,11 @@ class TypeMemberVisitor : public DeclVisitor<ImplClass, RetTy> {
     return RetTy();
   }
 
+  // These decls are disregarded.
+  RetTy visitPoundDiagnosticDecl(PoundDiagnosticDecl *D) {
+    return RetTy();
+  }
+
   /// A convenience method to visit all the members.
   void visitMembers(NominalTypeDecl *D) {
     for (Decl *member : D->getMembers()) {

include/swift/Parse/Parser.h

@@ -755,6 +755,9 @@ class Parser {
   ParserResult<IfConfigDecl> parseIfConfig(
     llvm::function_ref<void(SmallVectorImpl<ASTNode> &, bool)> parseElements);
 
+  /// Parse a #error or #warning diagnostic.
+  ParserResult<PoundDiagnosticDecl> parseDeclPoundDiagnostic();
+
   /// Parse a #line/#sourceLocation directive.
   /// 'isLine = true' indicates parsing #line instead of #sourcelocation
   ParserStatus parseLineDirective(bool isLine = false);

include/swift/SIL/SILWitnessVisitor.h

@@ -168,6 +168,10 @@ template <class T> class SILWitnessVisitor : public ASTVisitor<T> {
     // We only care about the active members, which were already subsumed by the
     // enclosing type.
   }
+
+  void visitPoundDiagnosticDecl(PoundDiagnosticDecl *pdd) {
+    // We don't care about diagnostics at this stage.
+  }
 };
 
 } // end namespace swift

include/swift/Syntax/TokenKinds.def

@@ -259,6 +259,8 @@ POUND_KEYWORD(keyPath)
 POUND_KEYWORD(line)
 POUND_KEYWORD(sourceLocation)
 POUND_KEYWORD(selector)
+POUND_KEYWORD(warning)
+POUND_KEYWORD(error)
 
 // Keywords prefixed with a '#' that are build configurations.
 POUND_CONFIG(available)

lib/AST/ASTDumper.cpp

@@ -1098,6 +1098,16 @@ namespace {
       PrintWithColorRAII(OS, ParenthesisColor) << ')';
     }
 
+    void visitPoundDiagnosticDecl(PoundDiagnosticDecl *PDD) {
+      printCommon(PDD, "pound_diagnostic_decl");
+      auto kind = PDD->isError() ? "error" : "warning";
+      OS << " kind=" << kind << "\n";
+      Indent += 2;
+      printRec(PDD->getMessage());
+      Indent -= 2;
+      PrintWithColorRAII(OS, ParenthesisColor) << ')';
+    }
+
     void visitPrecedenceGroupDecl(PrecedenceGroupDecl *PGD) {
       printCommon(PGD, "precedence_group_decl ");
       OS << PGD->getName() << "\n";

lib/AST/ASTPrinter.cpp

@@ -1917,6 +1917,17 @@ void PrintAST::visitIfConfigDecl(IfConfigDecl *ICD) {
   Printer << tok::pound_endif;
 }
 
+void PrintAST::visitPoundDiagnosticDecl(PoundDiagnosticDecl *PDD) {
+  /// TODO: Should we even print #error/#warning?
+  if (PDD->isError()) {
+    Printer << tok::pound_error;
+  } else {
+    Printer << tok::pound_warning; 
+  }
+
+  Printer << "(\"" << PDD->getMessage()->getValue() << "\")";
+}
+
 void PrintAST::visitTypeAliasDecl(TypeAliasDecl *decl) {
   printDocumentationComment(decl);
   printAttributes(decl);

lib/AST/ASTScope.cpp

@@ -881,6 +881,7 @@ ASTScope *ASTScope::createIfNeeded(const ASTScope *parent, Decl *decl) {
   case DeclKind::Param:
   case DeclKind::EnumElement:
   case DeclKind::IfConfig:
+  case DeclKind::PoundDiagnostic:
   case DeclKind::MissingMember:
     // These declarations do not introduce scopes.
     return nullptr;

lib/AST/ASTWalker.cpp

@@ -188,6 +188,11 @@ class Traversal : public ASTVisitor<Traversal, Expr*, Stmt*,
     return false;
   }
 
+  bool visitPoundDiagnosticDecl(PoundDiagnosticDecl *PDD) {
+    // By default, ignore #error/#warning.
+    return false;
+  }
+
   bool visitOperatorDecl(OperatorDecl *OD) {
     return false;
   }
@@ -1476,7 +1481,8 @@ Stmt *Traversal::visitSwitchStmt(SwitchStmt *S) {
       } else
         return nullptr;
     } else {
-      assert(isa<IfConfigDecl>(N.get<Decl*>()));
+      assert(isa<IfConfigDecl>(N.get<Decl*>()) || 
+             isa<PoundDiagnosticDecl>(N.get<Decl*>()));
       if (doIt(N.get<Decl*>()))
         return nullptr;
     }

lib/AST/Decl.cpp

@@ -125,6 +125,7 @@ DescriptiveDeclKind Decl::getDescriptiveKind() const {
   TRIVIAL_KIND(EnumCase);
   TRIVIAL_KIND(TopLevelCode);
   TRIVIAL_KIND(IfConfig);
+  TRIVIAL_KIND(PoundDiagnostic);
   TRIVIAL_KIND(PatternBinding);
   TRIVIAL_KIND(PrecedenceGroup);
   TRIVIAL_KIND(InfixOperator);
@@ -235,6 +236,7 @@ StringRef Decl::getDescriptiveKindName(DescriptiveDeclKind K) {
   ENTRY(EnumCase, "case");
   ENTRY(TopLevelCode, "top-level code");
   ENTRY(IfConfig, "conditional block");
+  ENTRY(PoundDiagnostic, "diagnostic");
   ENTRY(PatternBinding, "pattern binding");
   ENTRY(Var, "var");
   ENTRY(Param, "parameter");
@@ -769,6 +771,7 @@ ImportKind ImportDecl::getBestImportKind(const ValueDecl *VD) {
   case DeclKind::PostfixOperator:
   case DeclKind::EnumCase:
   case DeclKind::IfConfig:
+  case DeclKind::PoundDiagnostic:
   case DeclKind::PrecedenceGroup:
   case DeclKind::MissingMember:
     llvm_unreachable("not a ValueDecl");
@@ -1535,6 +1538,7 @@ bool ValueDecl::isDefinition() const {
   case DeclKind::PrefixOperator:
   case DeclKind::PostfixOperator:
   case DeclKind::IfConfig:
+  case DeclKind::PoundDiagnostic:
   case DeclKind::PrecedenceGroup:
   case DeclKind::MissingMember:
     assert(!isa<ValueDecl>(this));
@@ -1578,6 +1582,7 @@ bool ValueDecl::isInstanceMember() const {
   case DeclKind::PrefixOperator:
   case DeclKind::PostfixOperator:
   case DeclKind::IfConfig:
+  case DeclKind::PoundDiagnostic:
   case DeclKind::PrecedenceGroup:
   case DeclKind::MissingMember:
     llvm_unreachable("Not a ValueDecl");

lib/AST/Stmt.cpp

@@ -404,7 +404,8 @@ SwitchStmt *SwitchStmt::create(LabeledStmtInfo LabelInfo, SourceLoc SwitchLoc,
 #ifndef NDEBUG
   for (auto N : Cases)
     assert((N.is<Stmt*>() && isa<CaseStmt>(N.get<Stmt*>())) ||
-           (N.is<Decl*>() && isa<IfConfigDecl>(N.get<Decl*>())));
+           (N.is<Decl*>() && (isa<IfConfigDecl>(N.get<Decl*>()) ||
+                              isa<PoundDiagnosticDecl>(N.get<Decl*>()))));
 #endif
 
   void *p = C.Allocate(totalSizeToAlloc<ASTNode>(Cases.size()),

lib/FrontendTool/ReferenceDependencies.cpp

@@ -69,6 +69,7 @@ static bool declIsPrivate(const Decl *member) {
     case DeclKind::EnumCase:
     case DeclKind::TopLevelCode:
     case DeclKind::IfConfig:
+    case DeclKind::PoundDiagnostic:
       return true;
 
     case DeclKind::Extension:
@@ -240,6 +241,7 @@ bool swift::emitReferenceDependencies(DiagnosticEngine &diags,
     case DeclKind::PatternBinding:
     case DeclKind::TopLevelCode:
     case DeclKind::IfConfig:
+    case DeclKind::PoundDiagnostic:
       // No action necessary.
       break;
 

lib/IDE/CodeCompletion.cpp

@@ -548,6 +548,7 @@ CodeCompletionResult::getCodeCompletionDeclKind(const Decl *D) {
   case DeclKind::EnumCase:
   case DeclKind::TopLevelCode:
   case DeclKind::IfConfig:
+  case DeclKind::PoundDiagnostic:
   case DeclKind::MissingMember:
     llvm_unreachable("not expecting such a declaration result");
   case DeclKind::Module:

lib/IRGen/GenDecl.cpp

@@ -1881,7 +1881,8 @@ void IRGenModule::emitGlobalDecl(Decl *D) {
   case DeclKind::TypeAlias:
   case DeclKind::GenericTypeParam:
   case DeclKind::AssociatedType:
-  case DeclKind::IfConfig:
+  case DeclKind::IfConfig: 
+  case DeclKind::PoundDiagnostic:
     return;
 
   case DeclKind::Enum:
@@ -3345,6 +3346,7 @@ void IRGenModule::emitNestedTypeDecls(DeclRange members) {
       llvm_unreachable("decl not allowed in type context");
 
     case DeclKind::IfConfig:
+    case DeclKind::PoundDiagnostic:
       continue;
 
     case DeclKind::PatternBinding:

lib/Index/IndexSymbol.cpp

@@ -214,6 +214,7 @@ SymbolInfo index::getSymbolInfoForDecl(const Decl *D) {
     case DeclKind::EnumCase:
     case DeclKind::TopLevelCode:
     case DeclKind::IfConfig:
+    case DeclKind::PoundDiagnostic:
     case DeclKind::MissingMember:
     case DeclKind::Module:
       break;