Add support for a declaration attribute @warn for source-level warning group behavior control

include/swift/AST/ASTBridging.h

@@ -26,12 +26,15 @@
 #include "swift/AST/LayoutConstraintKind.h"
 #include "swift/AST/PlatformKind.h"
 #include "swift/Basic/BasicBridging.h"
+#include "swift/Basic/WarningGroupBehavior.h"
 
 #ifdef NOT_COMPILED_WITH_SWIFT_PURE_BRIDGING_MODE
 #include "swift/AST/Attr.h"
 #include "swift/AST/Decl.h"
 #endif
 
+#include <utility>
+
 SWIFT_BEGIN_NULLABILITY_ANNOTATIONS
 
 namespace llvm {
@@ -1104,11 +1107,36 @@ BridgedSwiftNativeObjCRuntimeBaseAttr_createParsed(BridgedASTContext cContext,
                                                    swift::SourceRange range,
                                                    swift::Identifier name);
 
+SWIFT_NAME("BridgedWarnAttr.createParsed(_:atLoc:range:diagGroupName:behavior:reason:)")
+BridgedWarnAttr
+BridgedWarnAttr_createParsed(BridgedASTContext cContext,
+                             swift::SourceLoc atLoc,
+                             swift::SourceRange range,
+                             swift::Identifier diagGroupName,
+                             swift::WarningGroupBehavior behavior,
+                             BridgedStringRef reason);
+
 enum ENUM_EXTENSIBILITY_ATTR(closed) BridgedNonSendableKind {
   BridgedNonSendableKindSpecific,
   BridgedNonSendableKindAssumed,
 };
 
+SWIFT_NAME("BridgedWarningGroupBehaviorRule.getGroupName(self:)")
+BridgedStringRef BridgedWarningGroupBehaviorRule_getGroupName(BridgedWarningGroupBehaviorRule rule);
+
+SWIFT_NAME("BridgedWarningGroupBehaviorRule.getBehavior(self:)")
+swift::WarningGroupBehavior
+BridgedWarningGroupBehaviorRule_getBehavior(BridgedWarningGroupBehaviorRule rule);
+
+
+SWIFT_NAME("getDiagnosticGroupLinksCount()")
+SwiftInt
+BridgedDiagnosticGroupLinks_getCount();
+
+SWIFT_NAME("getDiagnosticGroupLink(at:)")
+std::pair<BridgedStringRef, BridgedStringRef>
+BridgedDiagnosticGroupLinks_getLink(SwiftInt index);
+
 SWIFT_NAME("BridgedNonSendableAttr.createParsed(_:atLoc:range:kind:)")
 BridgedNonSendableAttr BridgedNonSendableAttr_createParsed(
     BridgedASTContext cContext, swift::SourceLoc atLoc,

include/swift/AST/ASTBridgingWrappers.def

@@ -114,6 +114,7 @@ AST_BRIDGING_WRAPPER_NONNULL(CustomAttribute)
 AST_BRIDGING_WRAPPER_NULLABLE(ArgumentList)
 AST_BRIDGING_WRAPPER_NULLABLE(AvailabilitySpec)
 AST_BRIDGING_WRAPPER_CONST_NONNULL(AvailabilityMacroMap)
+AST_BRIDGING_WRAPPER_NULLABLE(WarningGroupBehaviorRule)
 AST_BRIDGING_WRAPPER_NONNULL(PoundAvailableInfo)
 AST_BRIDGING_WRAPPER_NONNULL(LifetimeEntry)
 

include/swift/AST/Attr.h

@@ -23,6 +23,7 @@
 #include "swift/AST/AvailabilityRange.h"
 #include "swift/AST/ConcreteDeclRef.h"
 #include "swift/AST/DeclNameLoc.h"
+#include "swift/AST/DiagnosticGroups.h"
 #include "swift/AST/Identifier.h"
 #include "swift/AST/KnownProtocols.h"
 #include "swift/AST/LifetimeDependence.h"
@@ -41,6 +42,7 @@
 #include "swift/Basic/SourceLoc.h"
 #include "swift/Basic/UUID.h"
 #include "swift/Basic/Version.h"
+#include "swift/Basic/WarningGroupBehavior.h"
 #include "llvm/ADT/DenseMapInfo.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
@@ -3641,6 +3643,38 @@ class NonexhaustiveAttr : public DeclAttribute {
   }
 };
 
+class WarnAttr : public DeclAttribute {
+public:
+  WarnAttr(DiagGroupID DiagnosticGroupID, WarningGroupBehavior Behavior,
+           std::optional<StringRef> Reason, SourceLoc AtLoc, SourceRange Range,
+           bool Implicit)
+      : DeclAttribute(DeclAttrKind::Warn, AtLoc, Range, Implicit),
+        DiagnosticBehavior(Behavior), DiagnosticGroupID(DiagnosticGroupID),
+        Reason(Reason) {}
+
+  WarnAttr(DiagGroupID DiagnosticGroupID, WarningGroupBehavior Behavior, bool Implicit)
+      : WarnAttr(DiagnosticGroupID, Behavior, std::nullopt, SourceLoc(),
+                 SourceRange(), Implicit) {}
+
+  WarningGroupBehavior DiagnosticBehavior;
+  DiagGroupID DiagnosticGroupID;
+  const std::optional<StringRef> Reason;
+
+  static bool classof(const DeclAttribute *DA) {
+    return DA->getKind() == DeclAttrKind::Warn;
+  }
+
+  WarnAttr *clone(ASTContext &ctx) const {
+    return new (ctx) WarnAttr(DiagnosticGroupID, DiagnosticBehavior, Reason,
+                              AtLoc, Range, isImplicit());
+  }
+
+  bool isEquivalent(const WarnAttr *other,
+                    Decl *attachedTo) const {
+    return Reason == other->Reason;
+  }
+};
+
 
 /// The kind of unary operator, if any.
 enum class UnaryOperatorKind : uint8_t { None, Prefix, Postfix };

include/swift/AST/DeclAttr.def

@@ -902,12 +902,18 @@ DECL_ATTR(specialized, Specialized,
   AllowMultipleAttributes | LongAttribute | UserInaccessible | ABIStableToAdd | ABIStableToRemove | APIStableToAdd | APIStableToRemove | ForbiddenInABIAttr,
   172)
 
+
 SIMPLE_DECL_ATTR(_unsafeSelfDependentResult, UnsafeSelfDependentResult,
   OnAccessor,
   UserInaccessible | ABIStableToAdd | ABIStableToRemove | APIBreakingToAdd | APIBreakingToRemove | EquivalentInABIAttr,
   173)
 
-LAST_DECL_ATTR(UnsafeSelfDependentResult)
+DECL_ATTR(warn, Warn,
+  OnFunc | OnConstructor | OnDestructor | OnSubscript | OnVar | OnNominalType | OnExtension | OnAccessor | OnImport,
+  AllowMultipleAttributes | ABIStableToAdd | ABIStableToRemove | APIStableToAdd | APIStableToRemove | ForbiddenInABIAttr,
+  174)
+
+LAST_DECL_ATTR(Warn)
 
 #undef DECL_ATTR_ALIAS
 #undef CONTEXTUAL_DECL_ATTR_ALIAS

include/swift/AST/DiagnosticEngine.h

@@ -25,7 +25,7 @@
 #include "swift/Basic/PrintDiagnosticNamesMode.h"
 #include "swift/Basic/Statistic.h"
 #include "swift/Basic/Version.h"
-#include "swift/Basic/WarningAsErrorRule.h"
+#include "swift/Basic/WarningGroupBehaviorRule.h"
 #include "swift/Localization/LocalizationFormat.h"
 #include "llvm/ADT/BitVector.h"
 #include "llvm/ADT/StringRef.h"
@@ -612,6 +612,10 @@ namespace swift {
                                          ArrayRef<DiagnosticArgument> Args);
   };
 
+
+  using WarningGroupBehaviorMap =
+      std::unordered_map<swift::DiagGroupID, WarningGroupBehaviorRule>;
+
   /// Class to track, map, and remap diagnostic severity and fatality
   ///
   class DiagnosticState {
@@ -628,13 +632,13 @@ namespace swift {
     /// Don't emit any remarks
     bool suppressRemarks = false;
 
-    /// A mapping from `DiagGroupID` identifiers to Boolean values indicating
-    /// whether warnings belonging to the respective diagnostic groups should be
-    /// escalated to errors.
-    llvm::BitVector warningsAsErrors;
-
-    /// Track which diagnostic group (`DiagGroupID`) warnings should be ignored.
-    llvm::BitVector ignoredDiagnosticGroups;
+    /// A mapping from `DiagGroupID` identifiers to `WarningGroupBehaviorRule`
+    /// values indicating how warnings belonging to the respective diagnostic groups
+    /// should be emitted. While there is duplication between this data structure
+    /// being a map keyed with `DiagGroupID` and containing a rule object which also
+    /// contains a matching `DiagGroupID`, this significantly simplifies bridging
+    /// values of this map to Swift clients.
+    WarningGroupBehaviorMap warningGroupBehaviorMap;
 
     /// For compiler-internal purposes only, track which diagnostics should
     /// be ignored completely. For example, this is used by LLDB to
@@ -657,7 +661,8 @@ namespace swift {
 
     /// Figure out the Behavior for the given diagnostic, taking current
     /// state such as fatality into account.
-    DiagnosticBehavior determineBehavior(const Diagnostic &diag) const;
+    DiagnosticBehavior determineBehavior(const Diagnostic &diag,
+                                         SourceManager &sourceMgr) const;
 
     /// Updates the diagnostic state for a diagnostic to emit.
     void updateFor(DiagnosticBehavior behavior);
@@ -684,45 +689,37 @@ namespace swift {
     void setSuppressRemarks(bool val) { suppressRemarks = val; }
     bool getSuppressRemarks() const { return suppressRemarks; }
 
-    /// Sets whether warnings belonging to the diagnostic group identified by
-    /// `id` should be escalated to errors.
-    void setWarningsAsErrorsForDiagGroupID(DiagGroupID id, bool value) {
-      warningsAsErrors[(unsigned)id] = value;
+    /// Configure the command-line warning group handling
+    /// rules (`-Werrr`,`-Wwarning`,`-warnings-as-errors`)
+    void setWarningGroupControlRules(
+        const llvm::SmallVector<WarningGroupBehaviorRule, 4> &rules);
+
+    /// Add an individual command-line warning group behavior
+    void addWarningGroupControl(const DiagGroupID &groupID,
+                                WarningGroupBehavior behavior) {
+      warningGroupBehaviorMap.insert_or_assign(
+          groupID, WarningGroupBehaviorRule(behavior, groupID));
     }
 
-    /// Returns a Boolean value indicating whether warnings belonging to the
-    /// diagnostic group identified by `id` should be escalated to errors.
-    bool getWarningsAsErrorsForDiagGroupID(DiagGroupID id) const {
-      return warningsAsErrors[(unsigned)id];
+    const WarningGroupBehaviorMap&
+    getWarningGroupBehaviorControlMap() const {
+      return warningGroupBehaviorMap;
     }
 
-    /// Whether all warnings should be upgraded to errors or not.
-    void setAllWarningsAsErrors(bool value) {
-      // This works as intended because every diagnostic belongs to either a
-      // custom group or the top-level `DiagGroupID::no_group`, which is also
-      // a group.
-      if (value) {
-        warningsAsErrors.set();
-      } else {
-        warningsAsErrors.reset();
-      }
+    const std::vector<const WarningGroupBehaviorRule*>
+    getWarningGroupBehaviorControlRefArray() const {
+      std::vector<const WarningGroupBehaviorRule*> ruleRefArray;
+      ruleRefArray.reserve(warningGroupBehaviorMap.size());
+      for (const auto &rule: warningGroupBehaviorMap)
+        ruleRefArray.push_back(&rule.second);
+      return ruleRefArray;
     }
 
     void resetHadAnyError() {
       anyErrorOccurred = false;
       fatalErrorOccurred = false;
     }
 
-    /// Set whether a diagnostic group should be ignored.
-    void setIgnoredDiagnosticGroup(DiagGroupID id, bool ignored) {
-      ignoredDiagnosticGroups[(unsigned)id] = ignored;
-    }
-
-    /// Query whether a specific diagnostic group is ignored.
-    bool isIgnoredDiagnosticGroup(DiagGroupID id) const {
-      return ignoredDiagnosticGroups[(unsigned)id];
-    }
-
     /// Set a specific diagnostic to be ignored by the compiler.
     void compilerInternalIgnoreDiagnostic(DiagID id) {
       compilerIgnoredDiagnostics[(unsigned)id] = true;
@@ -738,11 +735,10 @@ namespace swift {
       std::swap(suppressWarnings, other.suppressWarnings);
       std::swap(suppressNotes, other.suppressNotes);
       std::swap(suppressRemarks, other.suppressRemarks);
-      std::swap(warningsAsErrors, other.warningsAsErrors);
+      std::swap(warningGroupBehaviorMap, other.warningGroupBehaviorMap);
       std::swap(fatalErrorOccurred, other.fatalErrorOccurred);
       std::swap(anyErrorOccurred, other.anyErrorOccurred);
       std::swap(previousBehavior, other.previousBehavior);
-      std::swap(ignoredDiagnosticGroups, other.ignoredDiagnosticGroups);
     }
 
   private:
@@ -752,6 +748,13 @@ namespace swift {
 
     DiagnosticState(DiagnosticState &&) = default;
     DiagnosticState &operator=(DiagnosticState &&) = default;
+
+    /// If this diagnostic is a warning belonging to a diagnostic group,
+    /// figure out if there is a source-level (`@warn`) control for this group
+    /// for this diagnostic's source location.
+    std::optional<DiagnosticBehavior>
+    determineUserControlledWarningBehavior(const Diagnostic &diag,
+                                           SourceManager &sourceMgr) const;
   };
 
   /// A lightweight reference to a diagnostic that's been fully applied to
@@ -951,7 +954,20 @@ namespace swift {
     /// Rules are applied in order they appear in the vector.
     /// In case the vector contains rules affecting the same diagnostic ID
     /// the last rule wins.
-    void setWarningsAsErrorsRules(const std::vector<WarningAsErrorRule> &rules);
+    void setWarningGroupControlRules(
+        const llvm::SmallVector<WarningGroupBehaviorRule, 4> &rules) {
+      state.setWarningGroupControlRules(rules);
+    }
+
+    const WarningGroupBehaviorMap&
+    getWarningGroupBehaviorControlMap() const {
+      return state.getWarningGroupBehaviorControlMap();
+    }
+
+    const std::vector<const WarningGroupBehaviorRule*>
+    getWarningGroupBehaviorControlRefArray() const {
+      return state.getWarningGroupBehaviorControlRefArray();
+    }
 
     /// Whether to print diagnostic names after their messages
     void setPrintDiagnosticNamesMode(PrintDiagnosticNamesMode val) {
@@ -982,13 +998,9 @@ namespace swift {
       localization = diag::LocalizationProducer::producerFor(locale, path);
     }
 
-    bool isIgnoredDiagnosticGroup(DiagGroupID id) const {
-      return state.isIgnoredDiagnosticGroup(id);
-    }
-
-    bool isIgnoredDiagnosticGroupTree(DiagGroupID id) const {
-      return state.isIgnoredDiagnosticGroupTree(id);
-    }
+    /// Whether the specified SourceFile enables a given diagnostic group
+    /// either syntactically, or via command-line flags.
+    bool isDiagnosticGroupEnabled(SourceFile *sf, DiagGroupID groupID) const;
 
     void ignoreDiagnostic(DiagID id) {
       state.compilerInternalIgnoreDiagnostic(id);
@@ -1366,7 +1378,8 @@ namespace swift {
           Engine.TentativeDiagnostics.end());
 
       for (auto &diagnostic : diagnostics) {
-        auto behavior = Engine.state.determineBehavior(diagnostic.Diag);
+        auto behavior = Engine.state.determineBehavior(diagnostic.Diag,
+                                                       Engine.SourceMgr);
         if (behavior == DiagnosticBehavior::Fatal ||
             behavior == DiagnosticBehavior::Error)
           return true;

include/swift/AST/DiagnosticsParse.def

@@ -1768,6 +1768,13 @@ WARNING(attr_warn_unused_result_removed,none,
         "'warn_unused_result' attribute behavior is now the default", ())
 ERROR(attr_warn_unused_result_expected_rparen,none,
       "expected ')' after 'warn_unused_result' attribute", ())
+
+// warn
+ERROR(attr_warn_expected_diagnostic_group_identifier,none,
+      "expected '%0' option to be a diagnostic group identifier", (StringRef))
+
+ERROR(attr_warn_expected_known_behavior,none,
+      "expected diagnostic behavior argument '%0' to be either 'error', 'warning' or 'ignored'", (StringRef))
 
 // _specialize
 ERROR(attr_specialize_missing_colon,none,

include/swift/Basic/DiagnosticOptions.h

@@ -14,7 +14,7 @@
 #define SWIFT_BASIC_DIAGNOSTICOPTIONS_H
 
 #include "swift/Basic/PrintDiagnosticNamesMode.h"
-#include "swift/Basic/WarningAsErrorRule.h"
+#include "swift/Basic/WarningGroupBehaviorRule.h"
 #include "llvm/ADT/Hashing.h"
 #include <vector>
 
@@ -76,7 +76,7 @@ class DiagnosticOptions {
   bool SuppressRemarks = false;
 
   /// Rules for escalating warnings to errors
-  std::vector<WarningAsErrorRule> WarningsAsErrorsRules;
+  llvm::SmallVector<WarningGroupBehaviorRule, 4> WarningGroupControlRules;
 
   /// When printing diagnostics, include either the diagnostic name
   /// (diag::whatever) at the end or the associated diagnostic group.

include/swift/Basic/Features.def

@@ -557,6 +557,9 @@ EXPERIMENTAL_FEATURE(AnyAppleOSAvailability, true)
 /// Check @_implementationOnly imports in non-library-evolution mode.
 EXPERIMENTAL_FEATURE(CheckImplementationOnly, true)
 
+/// Enable source-level warning control with `@warn`
+EXPERIMENTAL_FEATURE(SourceWarningControl, true)
+
 #undef EXPERIMENTAL_FEATURE_EXCLUDED_FROM_MODULE_INTERFACE
 #undef EXPERIMENTAL_FEATURE
 #undef UPCOMING_FEATURE

include/swift/Basic/LangOptions.h

@@ -674,7 +674,7 @@ namespace swift {
     /// Whether or not to allow experimental features that are only available
     /// in "production".
 #ifdef NDEBUG
-    bool RestrictNonProductionExperimentalFeatures = true;
+    bool RestrictNonProductionExperimentalFeatures = false;
 #else
     bool RestrictNonProductionExperimentalFeatures = false;
 #endif