Merge pull request swiftlang#29102 from DougGregor/function-builder-via-constraint-system

[Constraint solver] Use a constraint system to apply all function builders

Author: DougGregor

include/swift/AST/AnyFunctionRef.h

@@ -216,6 +216,15 @@ class AnyFunctionRef {
      return lhs.TheFunction != rhs.TheFunction;
    }
 
+  friend llvm::hash_code hash_value(AnyFunctionRef fn) {
+    using llvm::hash_value;
+    return hash_value(fn.TheFunction.getOpaqueValue());
+  }
+
+  friend SourceLoc extractNearestSourceLoc(AnyFunctionRef fn) {
+    return fn.getLoc();
+  }
+
 private:
   ArrayRef<AnyFunctionType::Yield>
   getYieldResultsImpl(SmallVectorImpl<AnyFunctionType::Yield> &buffer,
@@ -243,6 +252,8 @@ class AnyFunctionRef {
 #pragma warning(pop)
 #endif
 
+void simple_display(llvm::raw_ostream &out, AnyFunctionRef fn);
+
 } // namespace swift
 
 namespace llvm {

include/swift/AST/DiagnosticsSema.def

@@ -4815,6 +4815,13 @@ NOTE(previous_function_builder_here, none,
      "previous function builder specified here", ())
 ERROR(function_builder_arguments, none,
       "function builder attributes cannot have arguments", ())
+WARNING(function_builder_disabled_by_return, none,
+        "application of function builder %0 disabled by explicit 'return' "
+        "statement", (Type))
+NOTE(function_builder_remove_attr, none,
+     "remove the attribute to explicitly disable the function builder", ())
+NOTE(function_builder_remove_returns, none,
+     "remove 'return' statements to apply the function builder", ())
 
 //------------------------------------------------------------------------------
 // MARK: differentiable programming diagnostics

include/swift/AST/TypeCheckRequests.h

@@ -16,6 +16,7 @@
 #ifndef SWIFT_TYPE_CHECK_REQUESTS_H
 #define SWIFT_TYPE_CHECK_REQUESTS_H
 
+#include "swift/AST/AnyFunctionRef.h"
 #include "swift/AST/ASTTypeIDs.h"
 #include "swift/AST/GenericSignature.h"
 #include "swift/AST/Type.h"
@@ -1760,7 +1761,7 @@ enum class FunctionBuilderClosurePreCheck : uint8_t {
 
 class PreCheckFunctionBuilderRequest
     : public SimpleRequest<PreCheckFunctionBuilderRequest,
-                           FunctionBuilderClosurePreCheck(ClosureExpr *),
+                           FunctionBuilderClosurePreCheck(AnyFunctionRef),
                            CacheKind::Cached> {
 public:
   using SimpleRequest::SimpleRequest;
@@ -1770,7 +1771,7 @@ class PreCheckFunctionBuilderRequest
 
   // Evaluation.
   llvm::Expected<FunctionBuilderClosurePreCheck>
-  evaluate(Evaluator &evaluator, ClosureExpr *closure) const;
+  evaluate(Evaluator &evaluator, AnyFunctionRef fn) const;
 
 public:
   // Separate caching.

include/swift/AST/TypeCheckerTypeIDZone.def

@@ -196,7 +196,7 @@ SWIFT_REQUEST(TypeChecker, HasUserDefinedDesignatedInitRequest,
 SWIFT_REQUEST(TypeChecker, HasMemberwiseInitRequest,
               bool(StructDecl *), Cached, NoLocationInfo)
 SWIFT_REQUEST(TypeChecker, PreCheckFunctionBuilderRequest,
-              FunctionBuilderClosurePreCheck(ClosureExpr *),
+              FunctionBuilderClosurePreCheck(AnyFunctionRef),
               Cached, NoLocationInfo)
 SWIFT_REQUEST(TypeChecker, ResolveImplicitMemberRequest,
               bool(NominalTypeDecl *, ImplicitMemberAction), Uncached,

lib/AST/Decl.cpp

@@ -7903,3 +7903,10 @@ void ParseAbstractFunctionBodyRequest::cacheResult(BraceStmt *value) const {
   }
 
 }
+
+void swift::simple_display(llvm::raw_ostream &out, AnyFunctionRef fn) {
+  if (auto func = fn.getAbstractFunctionDecl())
+    simple_display(out, func);
+  else
+    out << "closure";
+}