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Allow dynamic replacement initializers to be non delegating #22691

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Merged
merged 2 commits into from
Feb 19, 2019
Merged

Allow dynamic replacement initializers to be non delegating #22691

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8f0fbd2
Allow dynamic replacement initializers to be non delegating
aschwaighofer Feb 18, 2019
d5b33ba
Only allow non resilient non-delegating initializers for now
aschwaighofer Feb 18, 2019
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4 changes: 3 additions & 1 deletion lib/AST/Decl.cpp
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Expand Up @@ -6342,8 +6342,10 @@ ConstructorDecl::getDelegatingOrChainedInitKind(DiagnosticEngine *diags,
// Prior to Swift 5, cross-module initializers were permitted to be
// non-delegating. However, if the struct isn't fixed-layout, we have to
// be delegating because, well, we don't know the layout.
// A dynamic replacement is permitted to be non-delegating.
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Even if the type is resilient?

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Yes I think you should be able to replace resilient constructors via dynamic replacement.

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Does the dynamic replacement module have visibility past the resilience boundary? It seems like that would require additional code, or building it with the IRGenOptions::EnableResilienceBypass flag set. Did you test this scenario?

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Here is what I have tested:

$ cat ModuleA.swift
struct S {
    let i: Int
    init(i: Int) {
        self.i = i
    }

    init(y: Int) {
      self.init(i: y)
    }
}

$ bin/swiftc -emit-library -Xfrontend -enable-private-imports -Xfrontend -enable-implicit-dynamic ModuleA.swift  -emit-module -enable-resilience

$ cat ModuleB.swift
@_private(sourceFile: "ModuleA.swift") import ModuleA

extension S {
  @_dynamicReplacement(for: init(i:))
  private init(__preview_i: Int) {
    self.i = __preview_i
  }
  @_dynamicReplacement(for: init(y:))
  private init(__preview_y: Int) {
    self.init(i: __preview_y)
  }
}

$ bin/swiftc -emit-library -Xfrontend -enable-private-imports -Xfrontend -enable-implicit-dynamic ModuleB.swift -I. -L. -lModuleA -Xfrontend -enable-resilience -emit-sil

// S.init(__preview_i:)
sil [dynamic_replacement_for "$s7ModuleA1SV1iACSi_tcfC"] @$s7ModuleA1SV0A1BE11__preview_iACSi_tc33_261761554CC3BA78F2BD69544DB6E8C4LlfC : $@convention(method) (Int, @thin S.Type) -> S {
// %0                                             // users: %8, %6, %3
bb0(%0 : $Int, %1 : $@thin S.Type):
  %2 = alloc_stack $S, var, name "self"           // users: %4, %9
  debug_value %0 : $Int, let, name "__preview_i", argno 1 // id: %3
  %4 = begin_access [modify] [static] %2 : $*S    // users: %7, %5
  %5 = struct_element_addr %4 : $*S, #S.i         // user: %6
  store %0 to %5 : $*Int                          // id: %6
  end_access %4 : $*S                             // id: %7
  %8 = struct $S (%0 : $Int)                      // user: %10
  dealloc_stack %2 : $*S                          // id: %9
  return %8 : $S                                  // id: %10
}

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What if S and S.init are both public?

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Hmm, that just crashes the compiler.

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I think we could make it work, if the dynamic replacement module is built with EnableResilienceBypass on.

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It crashes in SILGen. There are more dragons. I will deal with that later.

if (NTD->isResilient() ||
containingModule->getASTContext().isSwiftVersionAtLeast(5)) {
(containingModule->getASTContext().isSwiftVersionAtLeast(5) &&
!getAttrs().getAttribute<DynamicReplacementAttr>())) {
if (containingModule != NTD->getParentModule())
Kind = BodyInitKind::Delegating;
}
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3 changes: 2 additions & 1 deletion lib/Sema/TypeCheckDecl.cpp
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Expand Up @@ -4047,7 +4047,8 @@ void TypeChecker::validateDecl(ValueDecl *D) {
// (or the same file) to add vtable entries, we can re-evaluate this
// restriction.
if (extType->getClassOrBoundGenericClass() &&
isa<ExtensionDecl>(CD->getDeclContext())) {
isa<ExtensionDecl>(CD->getDeclContext()) &&
!(CD->getAttrs().hasAttribute<DynamicReplacementAttr>())) {
diagnose(CD->getLoc(), diag::designated_init_in_extension, extType)
.fixItInsert(CD->getLoc(), "convenience ");
CD->setInitKind(CtorInitializerKind::Convenience);
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32 changes: 32 additions & 0 deletions test/Sema/Inputs/dynamic_replacements_init_A.swift
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@@ -0,0 +1,32 @@
struct S {
let i: Int
init(i: Int) {
self.i = i
}

init(y: Int) {
self.init(i: y)
}
}

class A {
let i: Int
init(i: Int) {
self.i = i
}
convenience init(c: Int) {
self.init(i: c)
}
}

class B : A {
let b: Int
init(b: Int, i: Int) {
self.b = b
super.init(i: i)
}

convenience init(x: Int) {
self.init(b: x, i: x)
}
}
41 changes: 41 additions & 0 deletions test/Sema/dynamic_replacement_init.swift
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@@ -0,0 +1,41 @@
// RUN: %empty-directory(%t)
// RUN: %target-swift-frontend -swift-version 5 -enable-implicit-dynamic -enable-private-imports -emit-module -primary-file %S/Inputs/dynamic_replacements_init_A.swift -emit-module -module-name ModuleA -emit-module-path %t/ModuleA.swiftmodule
// RUN: %target-swift-frontend -swift-version 5 -typecheck -verify %s -I %t

@_private(sourceFile: "dynamic_replacements_init_A.swift") import ModuleA

extension S {
@_dynamicReplacement(for: init(i:))
private init(_i: Int) {
self.i = _i
}
@_dynamicReplacement(for: init(y:))
private init(_y: Int) {
self.init(i: _y)
}
}

extension A {
@_dynamicReplacement(for: init(i:))
private init(_i: Int) {
self.i = _i
}

@_dynamicReplacement(for: init(c:))
private convenience init(_y: Int) {
self.init(i: _y)
}
}

extension B {
@_dynamicReplacement(for: init(b:i:))
private init(_i: Int, _b: Int) {
self.b = _b
super.init(i: _i)
}

@_dynamicReplacement(for: init(x:))
private convenience init(_i: Int) {
self.init(b: _i, i: _i)
}
}