Sema: Replace TypeChecker::checkDeclarationAvailability().

Adopt `getUnmetDeclAvailabilityRequirement()` instead.

Author: tshortli

lib/Sema/BuilderTransform.cpp

@@ -1321,12 +1321,8 @@ ResultBuilderOpSupport TypeChecker::checkBuilderOpSupport(
     ArrayRef<Identifier> argLabels, SmallVectorImpl<ValueDecl *> *allResults) {
 
   auto isUnavailable = [&](Decl *D) -> bool {
-    if (AvailableAttr::isUnavailable(D))
-      return true;
-
     auto loc = extractNearestSourceLoc(dc);
-    auto context = ExportContext::forFunctionBody(dc, loc);
-    return TypeChecker::checkDeclarationAvailability(D, context).has_value();
+    return getUnmetDeclAvailabilityRequirement(D, dc, loc).has_value();
   };
 
   bool foundMatch = false;

lib/Sema/CSSyntacticElement.cpp

@@ -2475,10 +2475,9 @@ class ResultBuilderRewriter : public SyntacticElementSolutionApplication {
       if (!nominal)
         return false;
 
-      ExportContext where =
-          ExportContext::forFunctionBody(context.getAsDeclContext(), loc);
-      if (auto reason =
-              TypeChecker::checkDeclarationAvailability(nominal, where)) {
+      auto unmetRequirement = getUnmetDeclAvailabilityRequirement(
+          nominal, context.getAsDeclContext(), loc);
+      if (unmetRequirement && unmetRequirement->isConditionallySatisfiable()) {
         auto &ctx = getASTContext();
         ctx.Diags.diagnose(loc,
                            diag::result_builder_missing_limited_availability,

lib/Sema/ConstraintSystem.cpp

@@ -4897,12 +4897,12 @@ bool ConstraintSystem::isReadOnlyKeyPathComponent(
   // If the setter is unavailable, then the keypath ought to be read-only
   // in this context.
   if (auto setter = storage->getOpaqueAccessor(AccessorKind::Set)) {
-    ExportContext where = ExportContext::forFunctionBody(DC, referenceLoc);
-    auto maybeUnavail =
-        TypeChecker::checkDeclarationAvailability(setter, where);
-    if (maybeUnavail.has_value()) {
+    // FIXME: Fully unavailable setters should cause the key path to be
+    // readonly too.
+    auto unmetRequirement =
+        getUnmetDeclAvailabilityRequirement(setter, DC, referenceLoc);
+    if (unmetRequirement && unmetRequirement->isConditionallySatisfiable())
       return true;
-    }
   }
 
   return false;

lib/Sema/TypeCheckAvailability.cpp

@@ -1495,9 +1495,8 @@ static bool isDeclarationUnavailable(
   return !runningOSOverApprox.isContainedIn(safeRangeUnderApprox);
 }
 
-std::optional<AvailabilityRange>
-TypeChecker::checkDeclarationAvailability(const Decl *D,
-                                          const ExportContext &Where) {
+static std::optional<AvailabilityRange>
+checkDeclarationAvailability(const Decl *D, const ExportContext &Where) {
   // Skip computing potential unavailability if the declaration is explicitly
   // unavailable and the context is also unavailable.
   if (const AvailableAttr *Attr = AvailableAttr::isUnavailable(D))

lib/Sema/TypeChecker.h

@@ -1032,12 +1032,6 @@ diagnosticIfDeclCannotBePotentiallyUnavailable(const Decl *D);
 /// is allowed.
 std::optional<Diagnostic> diagnosticIfDeclCannotBeUnavailable(const Decl *D);
 
-/// Checks whether a declaration should be considered unavailable when
-/// referred to at the given location and, if so, returns the unmet required
-/// version range. Returns None is the declaration is definitely available.
-std::optional<AvailabilityRange>
-checkDeclarationAvailability(const Decl *D, const ExportContext &Where);
-
 /// Checks whether a conformance should be considered unavailable when
 /// referred to at the given location and, if so, returns the unmet required
 /// version range. Returns None is the declaration is definitely available.

test/expr/unary/keypath/keypath-availability.swift

@@ -33,3 +33,4 @@ public func conditionalAvailableSetterContext() {
     }
 }
 
+// FIXME: Check additional unavailability conditions