use full PackExpansion in diagnostic

Author: sophiapoirier

include/swift/AST/DiagnosticsSema.def

@@ -5310,7 +5310,7 @@ ERROR(vararg_not_allowed,none,
       "variadic parameter cannot appear outside of a function parameter list",
       ())
 ERROR(expansion_not_allowed,none,
-      "pack expansion repeat each %0 can only appear in a function parameter list, "
+      "pack expansion %0 can only appear in a function parameter list, "
       "tuple element, or generic argument list", (Type))
 ERROR(expansion_not_variadic,none,
       "pack expansion %0 must contain at least one pack reference", (Type))

include/swift/Basic/SourceLoc.h

@@ -157,7 +157,7 @@ class SourceRange {
 /// A half-open character-based source range.
 class CharSourceRange {
   SourceLoc Start;
-  unsigned ByteLength{};
+  unsigned ByteLength;
 
 public:
   /// Constructs an invalid range.

lib/Sema/TypeCheckType.cpp

@@ -4561,27 +4561,33 @@ NeverNullType TypeResolver::resolvePackExpansionType(PackExpansionTypeRepr *repr
     return ErrorType::get(ctx);
   }
 
+  PackExpansionType *result{};
+  GenericSignature genericSig;
+  Type shapeType;
+  if (resolution.getStage() == TypeResolutionStage::Interface) {
+    genericSig = resolution.getGenericSignature();
+    shapeType = genericSig->getReducedShape(rootParameterPacks[0]);
+    result = PackExpansionType::get(patternType, shapeType);
+  } else {
+    result = PackExpansionType::get(patternType, rootParameterPacks[0]);
+  }
+
   // We might not allow variadic expansions here at all.
   if (!options.isPackExpansionSupported(getDeclContext())) {
-    diagnose(repr->getLoc(), diag::expansion_not_allowed, patternType);
+    diagnose(repr->getLoc(), diag::expansion_not_allowed, result);
     return ErrorType::get(ctx);
   }
 
   if (resolution.getStage() == TypeResolutionStage::Interface) {
-    auto genericSig = resolution.getGenericSignature();
-    auto shapeType = genericSig->getReducedShape(rootParameterPacks[0]);
-    auto result = PackExpansionType::get(patternType, shapeType);
-
     for (auto type : rootParameterPacks) {
       if (!genericSig->haveSameShape(type, shapeType)) {
         ctx.Diags.diagnose(repr->getLoc(), diag::expansion_not_same_shape,
                            result, shapeType, type);
       }
     }
-    return result;
   }
 
-  return PackExpansionType::get(patternType, rootParameterPacks[0]);
+  return result;
 }
 
 NeverNullType TypeResolver::resolvePackElement(PackElementTypeRepr *repr,

test/Constraints/pack-expansion-expressions.swift

@@ -87,7 +87,7 @@ func sameShapeDiagnostics<each T, each U>(t: repeat each T, u: repeat each U) {
   _ = repeat (Array<each T>(), each u) // expected-error {{pack expansion requires that 'U' and 'T' have the same shape}}
 }
 
-func returnPackExpansionType<each T>(_ t: repeat each T) -> repeat each T { // expected-error {{pack expansion repeat each 'T' can only appear in a function parameter list, tuple element, or generic argument list}}
+func returnPackExpansionType<each T>(_ t: repeat each T) -> repeat each T { // expected-error {{pack expansion 'repeat each T' can only appear in a function parameter list, tuple element, or generic argument list}}
   fatalError()
 }
 

test/type/pack_expansion.swift

@@ -3,7 +3,7 @@
 // REQUIRES: asserts
 
 func f1<each T>() -> repeat each T {}
-// expected-error@-1 {{pack expansion repeat each 'T' can only appear in a function parameter list, tuple element, or generic argument list}}
+// expected-error@-1 {{pack expansion 'repeat each T' can only appear in a function parameter list, tuple element, or generic argument list}}
 
 func f2<each T>() -> (repeat each T) {}
 // okay
@@ -19,12 +19,12 @@ protocol P<T> {
 func f4<each T>() -> any P<repeat each T> {}
 
 typealias T1<each T> = repeat each T
-// expected-error@-1 {{pack expansion repeat each 'T' can only appear in a function parameter list, tuple element, or generic argument list}}
+// expected-error@-1 {{pack expansion 'repeat each T' can only appear in a function parameter list, tuple element, or generic argument list}}
 
 typealias T2<each T> = (repeat each T)
 
 func f4<each T>() -> repeat () -> each T {}
-// expected-error@-1 {{pack expansion repeat each '() -> T' can only appear in a function parameter list, tuple element, or generic argument list}}
+// expected-error@-1 {{pack expansion 'repeat () -> each T' can only appear in a function parameter list, tuple element, or generic argument list}}
 
 func f5<each T>() -> () -> (repeat each T) {}
 
@@ -36,20 +36,20 @@ enum E<each T> {
   case f2(_: G<repeat each T>)
 
   var x: repeat each T { fatalError() }
-  // expected-error@-1 {{pack expansion repeat each 'T' can only appear in a function parameter list, tuple element, or generic argument list}}
+  // expected-error@-1 {{pack expansion 'repeat each T' can only appear in a function parameter list, tuple element, or generic argument list}}
 
   var x: (repeat each T) { fatalError() }
 
   subscript(_: repeat each T) -> Int { fatalError() }
 
   subscript() -> repeat each T { fatalError() }
-  // expected-error@-1 {{pack expansion repeat each 'T' can only appear in a function parameter list, tuple element, or generic argument list}}
+  // expected-error@-1 {{pack expansion 'repeat each T' can only appear in a function parameter list, tuple element, or generic argument list}}
 
   subscript() -> (repeat each T) { fatalError() }
 }
 
 func withWhereClause<each T>(_ x: repeat each T) where repeat each T: P {}
-// expected-error@-1 {{pack expansion repeat each 'T' can only appear in a function parameter list, tuple element, or generic argument list}}
+// expected-error@-1 {{pack expansion 'repeat each T' can only appear in a function parameter list, tuple element, or generic argument list}}
 
 struct Outer<each T> {
   struct Bad<each U> {