Update diagnostics

Author: simanerush

include/swift/AST/DiagnosticsSema.def

@@ -5834,8 +5834,8 @@ ERROR(expansion_not_allowed,none,
       "pack expansion %0 can only appear in a function parameter list, "
       "tuple element, or generic argument of a variadic type", (Type))
 ERROR(expansion_expr_not_allowed,none,
-      "value pack expansion can only appear inside a function argument list "
-      "or tuple element", ())
+      "value pack expansion can only appear inside a function argument list, "
+      "tuple element, or as the expression of a for-in loop", ())
 ERROR(invalid_expansion_argument,none,
       "cannot pass value pack expansion to non-pack parameter of type %0",
       (Type))

test/Constraints/pack-expansion-expressions.swift

@@ -290,10 +290,10 @@ func concrete(_: Int) {}
 
 func invalidRepeat<each T>(t: repeat each T) {
   _ = repeat each t
-  // expected-error@-1 {{value pack expansion can only appear inside a function argument list or tuple element}}
+  // expected-error@-1 {{value pack expansion can only appear inside a function argument list, tuple element, or as the expression of a for-in loop}}
 
   let _: Int = repeat each t
-  // expected-error@-1 {{value pack expansion can only appear inside a function argument list or tuple element}}
+  // expected-error@-1 {{value pack expansion can only appear inside a function argument list, tuple element, or as the expression of a for-in loop}}
 
   identity(identity(repeat each t))
   // expected-error@-1 {{cannot pass value pack expansion to non-pack parameter of type 'T'}}
@@ -302,7 +302,7 @@ func invalidRepeat<each T>(t: repeat each T) {
   // expected-error@-1 {{cannot pass value pack expansion to non-pack parameter of type 'Int'}}
 
   _ = [repeat each t]
-  // expected-error@-1 {{value pack expansion can only appear inside a function argument list or tuple element}}
+  // expected-error@-1 {{value pack expansion can only appear inside a function argument list, tuple element, or as the expression of a for-in loop}}
 }
 
 // Make sure that single parameter initializers are handled correctly because

test/Constraints/variadic_generic_functions.swift

@@ -74,7 +74,7 @@ func contextualTyping() {
 do {
   func foo<each T>(_: repeat each T = bar().element) {} // expected-note {{in call to function 'foo'}}
   // expected-error@-1 {{variadic parameter cannot have a default value}}
-  // expected-error@-2 {{value pack expansion can only appear inside a function argument list or tuple element}}
+  // expected-error@-2 {{value pack expansion can only appear inside a function argument list, tuple element, or as the expression of a for-in loop}}
   // expected-error@-3 {{generic parameter 'each T' could not be inferred}}
 
   func bar<each T>() -> (repeat each T) {}