AST: Add llvm::raw_ostream conveniences for availability constructs.

Make it easier to debug availability by printing to output streams like
`llvm::errs()`.

NFC.

Author: tshortli

include/swift/AST/AvailabilityConstraint.h

@@ -23,6 +23,7 @@
 #include "swift/AST/PlatformKindUtils.h"
 #include "swift/Basic/LLVM.h"
 #include "swift/Basic/OptionSet.h"
+#include "llvm/Support/raw_ostream.h"
 
 namespace swift {
 
@@ -140,6 +141,8 @@ class AvailabilityConstraint {
   /// Some availability constraints are active for type-checking but cannot
   /// be translated directly into an `if #available(...)` runtime query.
   bool isActiveForRuntimeQueries(const ASTContext &ctx) const;
+
+  void print(raw_ostream &os) const;
 };
 
 /// Represents a set of availability constraints that restrict use of a
@@ -161,6 +164,8 @@ class DeclAvailabilityConstraints {
   using const_iterator = Storage::const_iterator;
   const_iterator begin() const { return constraints.begin(); }
   const_iterator end() const { return constraints.end(); }
+
+  void print(raw_ostream &os) const;
 };
 
 enum class AvailabilityConstraintFlag : uint8_t {
@@ -185,4 +190,21 @@ DeclAvailabilityConstraints getAvailabilityConstraintsForDecl(
     AvailabilityConstraintFlags flags = std::nullopt);
 } // end namespace swift
 
+namespace llvm {
+
+inline llvm::raw_ostream &
+operator<<(llvm::raw_ostream &os,
+           const swift::AvailabilityConstraint &constraint) {
+  constraint.print(os);
+  return os;
+}
+
+inline llvm::raw_ostream &
+operator<<(llvm::raw_ostream &os,
+           const swift::DeclAvailabilityConstraints &constraints) {
+  constraints.print(os);
+  return os;
+}
+
+} // end namespace llvm
 #endif

include/swift/AST/AvailabilityContext.h

@@ -23,6 +23,7 @@
 #include "swift/AST/PlatformKindUtils.h"
 #include "swift/Basic/Debug.h"
 #include "swift/Basic/LLVM.h"
+#include "llvm/Support/raw_ostream.h"
 #include <optional>
 
 namespace swift {
@@ -148,4 +149,14 @@ class AvailabilityContext {
 
 } // end namespace swift
 
+namespace llvm {
+
+inline llvm::raw_ostream &
+operator<<(llvm::raw_ostream &os, const swift::AvailabilityContext &context) {
+  context.print(os);
+  return os;
+}
+
+} // end namespace llvm
+
 #endif

include/swift/AST/AvailabilityDomain.h

@@ -28,6 +28,7 @@
 #include "llvm/ADT/FoldingSet.h"
 #include "llvm/ADT/PointerEmbeddedInt.h"
 #include "llvm/ADT/PointerUnion.h"
+#include "llvm/Support/raw_ostream.h"
 
 namespace swift {
 class ASTContext;
@@ -521,6 +522,12 @@ struct PointerLikeTypeTraits<swift::AvailabilityDomainOrIdentifier> {
   };
 };
 
+inline llvm::raw_ostream &operator<<(llvm::raw_ostream &os,
+                                     const swift::AvailabilityDomain &domain) {
+  domain.print(os);
+  return os;
+}
+
 } // end namespace llvm
 
 #endif

include/swift/AST/AvailabilityRange.h

@@ -21,7 +21,7 @@
 #include "swift/Basic/LLVM.h"
 #include "llvm/ADT/FoldingSet.h"
 #include "llvm/Support/VersionTuple.h"
-#include <optional>
+#include "llvm/Support/raw_ostream.h"
 
 namespace swift {
 class ASTContext;
@@ -317,11 +317,20 @@ class AvailabilityRange {
 
   /// Returns a representation of this range as a string for debugging purposes.
   std::string getAsString() const {
-    return "AvailabilityRange(" + getVersionString() + ")";
+    return "AvailabilityRange(" + getVersionDescription() + ")";
   }
 
-  /// Returns a representation of the raw version range as a string for
+  /// Returns a representation of the version range as a string for
   /// debugging purposes.
+  std::string getVersionDescription() const {
+    if (Range.hasLowerEndpoint())
+      return Range.getLowerEndpoint().getAsString();
+    else
+      return Range.isEmpty() ? "never" : "always";
+  }
+
+  /// Returns a string representation of the raw version range. It is an error
+  /// to call this if the range is "always" or "never".
   std::string getVersionString() const {
     ASSERT(Range.hasLowerEndpoint());
     return Range.getLowerEndpoint().getAsString();
@@ -330,4 +339,20 @@ class AvailabilityRange {
 
 } // end namespace swift
 
+namespace llvm {
+
+inline llvm::raw_ostream &operator<<(llvm::raw_ostream &os,
+                                     const swift::VersionRange &range) {
+  os << range.getAsString();
+  return os;
+}
+
+inline llvm::raw_ostream &operator<<(llvm::raw_ostream &os,
+                                     const swift::AvailabilityRange &range) {
+  os << range.getAsString();
+  return os;
+}
+
+} // namespace llvm
+
 #endif

include/swift/AST/AvailabilitySpec.h

@@ -27,6 +27,7 @@
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/iterator_range.h"
 #include "llvm/Support/VersionTuple.h"
+#include "llvm/Support/raw_ostream.h"
 
 namespace swift {
 class ASTContext;
@@ -241,4 +242,20 @@ class AvailabilityMacroMap {
 
 } // end namespace swift
 
+namespace llvm {
+
+inline llvm::raw_ostream &operator<<(llvm::raw_ostream &os,
+                                     const swift::AvailabilitySpec *spec) {
+  spec->print(os);
+  return os;
+}
+
+inline llvm::raw_ostream &
+operator<<(llvm::raw_ostream &os, const swift::SemanticAvailabilitySpec &spec) {
+  spec.print(os);
+  return os;
+}
+
+} // end namespace llvm
+
 #endif

lib/AST/AvailabilityConstraint.cpp

@@ -45,6 +45,27 @@ bool AvailabilityConstraint::isActiveForRuntimeQueries(
                                  /*forRuntimeQuery=*/true);
 }
 
+void AvailabilityConstraint::print(llvm::raw_ostream &os) const {
+  os << "AvailabilityConstraint(";
+  getAttr().getDomain().print(os);
+  os << ", ";
+
+  switch (getReason()) {
+  case Reason::UnconditionallyUnavailable:
+    os << "unavailable";
+    break;
+  case Reason::Obsoleted:
+    os << "obsoleted: " << getAttr().getObsoleted().value();
+    break;
+  case Reason::UnavailableForDeployment:
+  case Reason::PotentiallyUnavailable:
+    os << "introduced: " << getAttr().getIntroduced().value();
+    break;
+  }
+
+  os << ")";
+}
+
 static bool constraintIsStronger(const AvailabilityConstraint &lhs,
                                  const AvailabilityConstraint &rhs) {
   DEBUG_ASSERT(lhs.getDomain() == rhs.getDomain());
@@ -117,6 +138,17 @@ DeclAvailabilityConstraints::getPrimaryConstraint() const {
   return result;
 }
 
+void DeclAvailabilityConstraints::print(llvm::raw_ostream &os) const {
+  os << "{\n";
+  llvm::interleave(
+      constraints,
+      [&os](const AvailabilityConstraint &constraint) {
+        os << "  " << constraint;
+      },
+      [&os] { os << ",\n"; });
+  os << "\n}";
+}
+
 static bool canIgnoreConstraintInUnavailableContexts(
     const Decl *decl, const AvailabilityConstraint &constraint) {
   auto domain = constraint.getDomain();
@@ -293,3 +325,4 @@ swift::getAvailabilityConstraintsForDecl(const Decl *decl,
 
   return constraints;
 }
+