[ClangImporter] Add "suppressed" bit to SynthesizedProtocolAttr

Makes it possible to support `~Sendable` and potentially other
suppressible conformances.

Author: xedin

include/swift/AST/Attr.h

@@ -256,8 +256,9 @@ class DeclAttribute : public AttributeBase {
       kind : NumExternKindBits
     );
 
-    SWIFT_INLINE_BITFIELD(SynthesizedProtocolAttr, DeclAttribute, 1,
-      isUnchecked : 1
+    SWIFT_INLINE_BITFIELD(SynthesizedProtocolAttr, DeclAttribute, 2,
+      isUnchecked : 1,
+      isSuppressed: 1
     );
 
     SWIFT_INLINE_BITFIELD(ObjCImplementationAttr, DeclAttribute, 3,
@@ -1754,12 +1755,13 @@ class SynthesizedProtocolAttr : public DeclAttribute {
 
 public:
   SynthesizedProtocolAttr(ProtocolDecl *protocol, LazyConformanceLoader *Loader,
-                          bool isUnchecked)
+                          bool isUnchecked, bool isSuppressed)
       : DeclAttribute(DeclAttrKind::SynthesizedProtocol, SourceLoc(),
                       SourceRange(),
                       /*Implicit=*/true),
         Loader(Loader), protocol(protocol) {
     Bits.SynthesizedProtocolAttr.isUnchecked = unsigned(isUnchecked);
+    Bits.SynthesizedProtocolAttr.isSuppressed = unsigned(isSuppressed);
   }
 
   /// Retrieve the known protocol kind naming the protocol to be
@@ -1772,6 +1774,10 @@ class SynthesizedProtocolAttr : public DeclAttribute {
     return bool(Bits.SynthesizedProtocolAttr.isUnchecked);
   }
 
+  bool isSuppressed() const {
+    return bool(Bits.SynthesizedProtocolAttr.isSuppressed);
+  }
+
   /// Retrieve the lazy loader that will be used to populate the
   /// synthesized conformance.
   LazyConformanceLoader *getLazyLoader() const { return Loader; }
@@ -1782,12 +1788,13 @@ class SynthesizedProtocolAttr : public DeclAttribute {
 
   SynthesizedProtocolAttr *clone(ASTContext &ctx) const {
     return new (ctx) SynthesizedProtocolAttr(
-        protocol, getLazyLoader(), isUnchecked());
+        protocol, getLazyLoader(), isUnchecked(), isSuppressed());
   }
 
   bool isEquivalent(const SynthesizedProtocolAttr *other,
                     Decl *attachedTo) const {
     return isUnchecked() == other->isUnchecked()
+            && isSuppressed() == other->isSuppressed()
             && getProtocol() == other->getProtocol()
             && getLazyLoader() == other->getLazyLoader();
   }

lib/AST/ASTPrinter.cpp

@@ -8270,6 +8270,7 @@ swift::getInheritedForPrinting(
   // Collect synthesized conformances.
   llvm::SetVector<ProtocolDecl *> protocols;
   llvm::TinyPtrVector<ProtocolDecl *> uncheckedProtocols;
+  llvm::TinyPtrVector<ProtocolDecl *> suppressedProtocols;
   for (auto attr : decl->getAttrs().getAttributes<SynthesizedProtocolAttr>()) {
     if (auto *proto = attr->getProtocol()) {
       // FIXME: Reconstitute inverses here
@@ -8289,12 +8290,15 @@ swift::getInheritedForPrinting(
       protocols.insert(proto);
       if (attr->isUnchecked())
         uncheckedProtocols.push_back(proto);
+      if (attr->isSuppressed())
+        suppressedProtocols.push_back(proto);
     }
   }
 
   for (size_t i = 0; i < protocols.size(); i++) {
     auto proto = protocols[i];
     bool isUnchecked = llvm::is_contained(uncheckedProtocols, proto);
+    bool isSuppressed = llvm::is_contained(suppressedProtocols, proto);
 
     if (!options.shouldPrint(proto)) {
       // If private stdlib protocols are skipped and this is a private stdlib
@@ -8319,7 +8323,7 @@ swift::getInheritedForPrinting(
     if (isUnchecked)
       options |= ProtocolConformanceFlags::Unchecked;
     Results.push_back({TypeLoc::withoutLoc(proto->getDeclaredInterfaceType()),
-                       options});
+                       options, isSuppressed});
   }
 }
 

lib/ClangImporter/ImportDecl.cpp

@@ -503,7 +503,8 @@ void ClangImporter::Implementation::addSynthesizedTypealias(
 
 void ClangImporter::Implementation::addSynthesizedProtocolAttrs(
     NominalTypeDecl *nominal,
-    ArrayRef<KnownProtocolKind> synthesizedProtocolAttrs, bool isUnchecked) {
+    ArrayRef<KnownProtocolKind> synthesizedProtocolAttrs, bool isUnchecked,
+    bool isSuppressed) {
   auto &ctx = nominal->getASTContext();
 
   for (auto kind : synthesizedProtocolAttrs) {
@@ -512,7 +513,7 @@ void ClangImporter::Implementation::addSynthesizedProtocolAttrs(
     // ctx.getProtocol(kind) != nulltpr which would be nice.
     if (auto proto = ctx.getProtocol(kind))
       nominal->addAttribute(
-          new (ctx) SynthesizedProtocolAttr(proto, this, isUnchecked));
+        new (ctx) SynthesizedProtocolAttr(proto, this, isUnchecked, isSuppressed));
   }
 }
 
@@ -9470,8 +9471,8 @@ void ClangImporter::Implementation::addExplicitProtocolConformance(
                decl->getDeclaredInterfaceType(), conformsToValue);
     }
 
-    decl->addAttribute(new (SwiftContext)
-                           SynthesizedProtocolAttr(protocol, this, false));
+    decl->addAttribute(new (SwiftContext) SynthesizedProtocolAttr(
+        protocol, this, /*isUnchecked=*/false, /*isSuppressed=*/false));
   } else {
     HeaderLoc attrLoc((conformsToAttr)->getLocation());
     diagnose(attrLoc, diag::conforms_to_not_protocol, result,

lib/ClangImporter/ImporterImpl.h

@@ -1264,7 +1264,8 @@ class LLVM_LIBRARY_VISIBILITY ClangImporter::Implementation
   void addSynthesizedProtocolAttrs(
       NominalTypeDecl *nominal,
       ArrayRef<KnownProtocolKind> synthesizedProtocolAttrs,
-      bool isUnchecked = false);
+      bool isUnchecked = false,
+      bool isSuppressed = false);
 
   void makeComputed(AbstractStorageDecl *storage, AccessorDecl *getter,
                     AccessorDecl *setter);