Fix a compiler crash with '@'_lifetime(inout x), add diagnostic

This is a common mistake made more common be suggestions of existing diagnostic
that tell users not to use a 'copy' dependency.

Report a diagnostic error rather than crashing the compiler. Fix the diagnostic
output to make sense relative to the source location.

Fixes rdar://154136015 ([nonescapable] compiler assertion with @_lifetime(x: inout x))

Author: atrick

include/swift/AST/DiagnosticsParse.def

@@ -2147,7 +2147,7 @@ ERROR(expected_lparen_after_lifetime_dependence, PointsToFirstBadToken,
 
 ERROR(expected_identifier_or_index_or_self_after_lifetime_dependence,
       PointsToFirstBadToken,
-      "expected identifier, index or self in lifetime dependence specifier",
+      "expected 'copy', 'borrow', or '&' followed by an identifier, index or 'self' in lifetime dependence specifier",
       ())
 
 ERROR(expected_rparen_after_lifetime_dependence, PointsToFirstBadToken,

lib/Parse/ParseDecl.cpp

@@ -5014,6 +5014,7 @@ ParserResult<LifetimeEntry> Parser::parseLifetimeEntry(SourceLoc loc) {
   SmallVector<LifetimeDescriptor> sources;
   SourceLoc rParenLoc;
   bool foundParamId = false;
+  bool invalidSourceDescriptor = false;
   status = parseList(
       tok::r_paren, lParenLoc, rParenLoc, /*AllowSepAfterLast=*/false,
       diag::expected_rparen_after_lifetime_dependence, [&]() -> ParserStatus {
@@ -5030,13 +5031,18 @@ ParserResult<LifetimeEntry> Parser::parseLifetimeEntry(SourceLoc loc) {
         auto sourceDescriptor =
             parseLifetimeDescriptor(*this, lifetimeDependenceKind);
         if (!sourceDescriptor) {
+          invalidSourceDescriptor = true;
           listStatus.setIsParseError();
           return listStatus;
         }
         sources.push_back(*sourceDescriptor);
         return listStatus;
       });
 
+  if (invalidSourceDescriptor) {
+    status.setIsParseError();
+    return status;
+  }
   if (!foundParamId) {
     diagnose(
         Tok,

test/Parse/lifetime_attr.swift

@@ -24,7 +24,7 @@ func testMissingLParenError(_ ne: NE) -> NE { // expected-error{{cannot infer th
   ne
 }
 
-@_lifetime() // expected-error{{expected identifier, index or self in lifetime dependence specifier}}
+@_lifetime() // expected-error{{expected 'copy', 'borrow', or '&' followed by an identifier, index or 'self' in lifetime dependence specifier}}
 func testMissingDependence(_ ne: NE) -> NE { // expected-error{{cannot infer the lifetime dependence scope on a function with a ~Escapable parameter, specify '@_lifetime(borrow ne)' or '@_lifetime(copy ne)'}}
   ne
 }

test/Sema/lifetime_depend_infer.swift

@@ -588,3 +588,8 @@ struct NonEscapableMutableSelf: ~Escapable {
 //
 func f_inout_no_infer(a: inout MutNE, b: NE) {} // expected-error{{a function with a ~Escapable 'inout' parameter requires '@_lifetime(a: ...)'}}
 // expected-note @-1{{use '@_lifetime(a: copy a) to forward the inout dependency}}
+
+// Invalid keyword for the dependence kind.
+//
+@_lifetime(a: inout a) // expected-error{{expected 'copy', 'borrow', or '&' followed by an identifier, index or 'self' in lifetime dependence specifier}}
+func f_inout_bad_keyword(a: inout MutableRawSpan) {}