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

Author: harlanhaskins

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)