[AST] Remove @escaping from decl attributes.

@escaping is not really a decl attribute, ever since it was introduced.

Author: rintaro

include/swift/AST/Attr.def

@@ -262,8 +262,6 @@ SIMPLE_DECL_ATTR(discardableResult, DiscardableResult,
 
 SIMPLE_DECL_ATTR(GKInspectable, GKInspectable, OnVar, 66)
 
-SIMPLE_DECL_ATTR(escaping, Escaping, OnParam, 67)
-
 #undef TYPE_ATTR
 #undef DECL_ATTR_ALIAS
 #undef SIMPLE_DECL_ATTR

lib/Sema/TypeCheckAttr.cpp

@@ -155,15 +155,6 @@ class AttributeEarlyChecker : public AttributeVisitor<AttributeEarlyChecker> {
     TC.checkNoEscapeAttr(cast<ParamDecl>(D), attr);
   }
 
-  void visitEscapingAttr(EscapingAttr *attr) {
-    auto *PD = cast<ParamDecl>(D);
-    auto *FTy = PD->getType()->getAs<FunctionType>();
-    if (FTy == 0) {
-      TC.diagnose(attr->getLocation(), diag::escaping_function_type);
-      attr->setInvalid();
-    }
-  }
-
   void visitTransparentAttr(TransparentAttr *attr);
   void visitMutationAttr(DeclAttribute *attr);
   void visitMutatingAttr(MutatingAttr *attr) { visitMutationAttr(attr); }
@@ -742,7 +733,6 @@ class AttributeChecker : public AttributeVisitor<AttributeChecker> {
     IGNORED_ATTR(WarnUnqualifiedAccess)
     IGNORED_ATTR(ShowInInterface)
     IGNORED_ATTR(DiscardableResult)
-    IGNORED_ATTR(Escaping)
 
     // FIXME: We actually do have things to enforce for versioned API.
     IGNORED_ATTR(Versioned)

lib/Sema/TypeCheckDecl.cpp

@@ -5920,7 +5920,6 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
     // These can't appear on overridable declarations.
     UNINTERESTING_ATTR(AutoClosure)
     UNINTERESTING_ATTR(NoEscape)
-    UNINTERESTING_ATTR(Escaping)
 
     UNINTERESTING_ATTR(Prefix)
     UNINTERESTING_ATTR(Postfix)

test/IDE/complete_decl_attribute.swift

@@ -35,10 +35,9 @@
 
 func method(@#^KEYWORD1^#) {}
 
-// KEYWORD1:                  Begin completions, 3 items
+// KEYWORD1:                  Begin completions, 2 items
 // KEYWORD1-NEXT:             Keyword/None:                       autoclosure[#Param Attribute#]; name=autoclosure{{$}}
 // KEYWORD1-NEXT:             Keyword/None:                       noescape[#Param Attribute#]; name=noescape{{$}}
-// KEYWORD1-NEXT:             Keyword/None:                       escaping[#Param Attribute#]; name=escaping{{$}}
 // KEYWORD1-NEXT:             End completions
 
 @#^KEYWORD2^#
@@ -86,7 +85,7 @@ struct S{}
 
 @#^KEYWORD_LAST^#
 
-// KEYWORD_LAST:                  Begin completions, 21 items
+// KEYWORD_LAST:                  Begin completions, 20 items
 // KEYWORD_LAST-NEXT:             Keyword/None:                       available[#Declaration Attribute#]; name=available{{$}}
 // KEYWORD_LAST-NEXT:             Keyword/None:                       objc[#Declaration Attribute#]; name=objc{{$}}
 // KEYWORD_LAST-NEXT:             Keyword/None:                       noreturn[#Declaration Attribute#]; name=noreturn{{$}}
@@ -107,5 +106,4 @@ struct S{}
 // KEYWORD_LAST-NEXT:             Keyword/None:                       warn_unqualified_access[#Declaration Attribute#]; name=warn_unqualified_access
 // KEYWORD_LAST-NEXT:             Keyword/None:                       discardableResult[#Declaration Attribute#]; name=discardableResult
 // KEYWORD_LAST-NEXT:             Keyword/None:                       GKInspectable[#Declaration Attribute#]; name=GKInspectable{{$}}
-// KEYWORD_LAST-NEXT:             Keyword/None:                       escaping[#Declaration Attribute#]; name=escaping{{$}}
 // KEYWORD_LAST-NEXT:             End completions

test/attr/attr_escaping.swift

@@ -1,6 +1,7 @@
 // RUN: %target-parse-verify-swift
 
-@escaping var fn : () -> Int = { 4 }  // expected-error {{@escaping may only be used on 'parameter' declarations}} {{1-11=}}
+@escaping var fn : () -> Int = { 4 }  // expected-error {{attribute can only be applied to types, not declarations}}
+func paramDeclEscaping(@escaping fn: (Int) -> Void) {} // expected-error {{attribute can only be applied to types, not declarations}}
 
 func wrongParamType(a: @escaping Int) {} // expected-error {{@escaping attribute only applies to function types}}