Parse: Backward compatibility for old spellings @_inlineable and @_versioned

Just parse these as @inlinable and @versioned, then emit a warning
(Swift 4.2 and below) or error (Swift 5).

Author: slavapestov

include/swift/AST/DiagnosticsParse.def

@@ -1311,6 +1311,12 @@ ERROR(attr_only_on_parameters_parse, none,
 ERROR(attr_access_expected_set,none,
       "expected 'set' as subject of '%0' modifier", (StringRef))
 
+// Attributes
+ERROR(attr_renamed, none,
+      "'@%0' has been renamed to '@%1'", (StringRef, StringRef))
+WARNING(attr_renamed_warning, none,
+        "'@%0' has been renamed to '@%1'", (StringRef, StringRef))
+
 // availability
 ERROR(attr_availability_platform,none,
       "expected platform name or '*' for '%0' attribute", (StringRef))
@@ -1319,7 +1325,7 @@ ERROR(attr_availability_unavailable_deprecated,none,
       "'deprecated'", (StringRef))
 
 WARNING(attr_availability_unknown_platform,none,
-"unknown platform '%0' for attribute '%1'", (StringRef, StringRef))
+      "unknown platform '%0' for attribute '%1'", (StringRef, StringRef))
 ERROR(attr_availability_invalid_renamed,none,
       "'renamed' argument of '%0' attribute must be an operator, identifier, "
       "or full function name, optionally prefixed by a type name", (StringRef))
@@ -1334,9 +1340,6 @@ ERROR(attr_availability_expected_equal,none,
 ERROR(attr_availability_expected_version,none,
       "expected version number in '%0' attribute", (StringRef))
 
-ERROR(attr_availability_renamed, none,
-      "@availability has been renamed to @available", ())
-
 // autoclosure
 ERROR(attr_autoclosure_expected_r_paren,PointsToFirstBadToken,
       "expected ')' in @autoclosure", ())

lib/Parse/ParseDecl.cpp

@@ -1354,7 +1354,9 @@ bool Parser::parseNewDeclAttribute(DeclAttributes &Attributes, SourceLoc AtLoc,
   if (DuplicateAttribute) {
     diagnose(Loc, diag::duplicate_attribute, DeclAttribute::isDeclModifier(DK))
       .highlight(AttrRange);
-    diagnose(DuplicateAttribute->getLocation(), diag::previous_attribute, DeclAttribute::isDeclModifier(DK))
+    diagnose(DuplicateAttribute->getLocation(),
+             diag::previous_attribute,
+             DeclAttribute::isDeclModifier(DK))
       .highlight(DuplicateAttribute->getRange());
   }
 
@@ -1464,14 +1466,35 @@ bool Parser::parseDeclAttribute(DeclAttributes &Attributes, SourceLoc AtLoc) {
   // over to the alternate parsing path.
   DeclAttrKind DK = DeclAttribute::getAttrKindFromString(Tok.getText());
 
-  if (DK == DAK_Count && Tok.getText() == "availability") {
-    // We renamed @availability to @available, so if we see the former,
-    // treat it as the latter and emit a Fix-It.
-    DK = DAK_Available;
-    diagnose(Tok, diag::attr_availability_renamed)
-        .fixItReplace(Tok.getLoc(), "available");
-  }
+  auto checkRenamedAttr = [&](StringRef oldName, StringRef newName,
+                              DeclAttrKind kind, bool warning) {
+    if (DK == DAK_Count && Tok.getText() == oldName) {
+      // We renamed @availability to @available, so if we see the former,
+      // treat it as the latter and emit a Fix-It.
+      DK = kind;
+      if (warning) {
+        diagnose(Tok, diag::attr_renamed_warning, oldName, newName)
+            .fixItReplace(Tok.getLoc(), newName);
+      } else {
+        diagnose(Tok, diag::attr_renamed, oldName, newName)
+            .fixItReplace(Tok.getLoc(), newName);
+      }
+    }
+  };
+
+  // FIXME: This renaming happened before Swift 3, we can probably remove
+  // the specific fallback path at some point.
+  checkRenamedAttr("availability", "available", DAK_Available, false);
 
+  // In Swift 5 and above, these become hard errors. Otherwise, emit a
+  // warning for compatibility.
+  if (!Context.isSwiftVersionAtLeast(5)) {
+    checkRenamedAttr("_versioned", "usableFromInline", DAK_UsableFromInline, true);
+    checkRenamedAttr("_inlineable", "inlinable", DAK_Inlinable, true);
+  } else {
+    checkRenamedAttr("_versioned", "usableFromInline", DAK_UsableFromInline, false);
+    checkRenamedAttr("_inlineable", "inlinable", DAK_Inlinable, false);
+  }
 
   if (DK == DAK_Count && Tok.getText() == "warn_unused_result") {
     // The behavior created by @warn_unused_result is now the default. Emit a

test/Compatibility/attr_inlinable_old_spelling.swift

@@ -0,0 +1,11 @@
+// RUN: %target-typecheck-verify-swift -swift-version 3
+// RUN: %target-typecheck-verify-swift -swift-version 4
+// RUN: %target-typecheck-verify-swift -swift-version 4.2
+
+// Until -swift-version 5 mode, the old spelling only produces a warning.
+
+@_inlineable public func oldInlinableFunction() {}
+// expected-warning@-1 {{'@_inlineable' has been renamed to '@inlinable'}}{{2-13=inlinable}}
+
+@_versioned func oldVersionedFunction() {}
+// expected-warning@-1 {{'@_versioned' has been renamed to '@usableFromInline'}}{{2-12=usableFromInline}}

test/attr/attr_availability.swift

@@ -228,7 +228,7 @@ func shortFormWithWildcardInMiddle() {}
 @available(iOS 8.0, OSX 10.10.3) // expected-error {{must handle potential future platforms with '*'}} {{32-32=, *}}
 func shortFormMissingWildcard() {}
 
-@availability(OSX, introduced: 10.10) // expected-error {{@availability has been renamed to @available}} {{2-14=available}}
+@availability(OSX, introduced: 10.10) // expected-error {{'@availability' has been renamed to '@available'}} {{2-14=available}}
 func someFuncUsingOldAttribute() { }
 
 

test/attr/attr_inlinable_old_spelling.swift

@@ -0,0 +1,7 @@
+// RUN: %target-typecheck-verify-swift -swift-version 5
+
+@_inlineable public func oldInlinableFunction() {}
+// expected-error@-1 {{'@_inlineable' has been renamed to '@inlinable'}}{{2-13=inlinable}}
+
+@_versioned func oldVersionedFunction() {}
+// expected-error@-1 {{'@_versioned' has been renamed to '@usableFromInline'}}{{2-12=usableFromInline}}