Assertion in typechecker

[asl]

Description

Consider the attached testcase. The typechecker fails with the assertion:

Assertion failed: (!resolvedType->hasArchetype()), function resolveInterfaceType, file ConstraintSystem.cpp, line 4030.

Reproduction

import _Differentiation

func validate<S, T>(function: @differentiable(reverse) (S) -> (T), with truth: (S) -> (T), at point: S) where S: Differentiable, T: Differentiable, T: FloatingPoint {
    let vwpb = valueWithPullback(at: point, of: function)
    let truthValue = truth(point)
    let gradient = vwpb.pullback(1.0)
    gradient == truthValue
}

Stack dump

0  swift-frontend           0x0000000109e20af4 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) + 56
1  swift-frontend           0x0000000109e1f244 llvm::sys::RunSignalHandlers() + 112
2  swift-frontend           0x0000000109e21138 SignalHandler(int) + 292
3  libsystem_platform.dylib 0x000000019cff0184 _sigtramp + 56
4  libsystem_pthread.dylib  0x000000019cfbaf70 pthread_kill + 288
5  libsystem_c.dylib        0x000000019cec7908 abort + 128
6  libsystem_c.dylib        0x000000019cec6c1c err + 0
7  swift-frontend           0x0000000109f10650 swift::constraints::Solution::getFunctionArgApplyInfo(swift::constraints::ConstraintLocator*) const (.cold.1) + 0
8  swift-frontend           0x0000000105c77ec0 swift::constraints::Solution::getFunctionArgApplyInfo(swift::constraints::ConstraintLocator*) const + 1192
9  swift-frontend           0x0000000105c0d0e8 swift::constraints::AllowArgumentMismatch::diagnose(swift::constraints::Solution const&, bool) const + 68
10 swift-frontend           0x0000000105b4b0f0 swift::constraints::ConstraintSystem::applySolutionFixes(swift::constraints::Solution const&) + 1272
11 swift-frontend           0x0000000105b4b6f4 swift::constraints::ConstraintSystem::applySolution(swift::constraints::Solution&, swift::constraints::SyntacticElementTarget) + 80
12 swift-frontend           0x0000000105d6c5a0 swift::TypeChecker::typeCheckTarget(swift::constraints::SyntacticElementTarget&, swift::optionset::OptionSet<swift::TypeCheckExprFlags, unsigned int>, swift::DiagnosticTransaction*) + 372
13 swift-frontend           0x0000000105d6c3d0 swift::TypeChecker::typeCheckExpression(swift::constraints::SyntacticElementTarget&, swift::optionset::OptionSet<swift::TypeCheckExprFlags, unsigned int>, swift::DiagnosticTransaction*) + 196
14 swift-frontend           0x0000000105d6d668 swift::TypeChecker::typeCheckBinding(swift::Pattern*&, swift::Expr*&, swift::DeclContext*, swift::Type, swift::PatternBindingDecl*, unsigned int, swift::optionset::OptionSet<swift::TypeCheckExprFlags, unsigned int>) + 124
15 swift-frontend           0x0000000105d6d8a0 swift::TypeChecker::typeCheckPatternBinding(swift::PatternBindingDecl*, unsigned int, swift::Type, swift::optionset::OptionSet<swift::TypeCheckExprFlags, unsigned int>) + 248
16 swift-frontend           0x0000000105e42a88 swift::PatternBindingEntryRequest::evaluate(swift::Evaluator&, swift::PatternBindingDecl*, unsigned int) const + 2344
17 swift-frontend           0x000000010613939c swift::PatternBindingEntryRequest::OutputType swift::Evaluator::getResultUncached<swift::PatternBindingEntryRequest, swift::PatternBindingEntryRequest::OutputType swift::evaluateOrDefault<swift::PatternBindingEntryRequest>(swift::Evaluator&, swift::PatternBindingEntryRequest, swift::PatternBindingEntryRequest::OutputType)::'lambda'()>(swift::PatternBindingEntryRequest const&, swift::PatternBindingEntryRequest::OutputType swift::evaluateOrDefault<swift::PatternBindingEntryRequest>(swift::Evaluator&, swift::PatternBindingEntryRequest, swift::PatternBindingEntryRequest::OutputType)::'lambda'()) + 212
18 swift-frontend           0x000000010610bfb0 swift::PatternBindingDecl::getCheckedPatternBindingEntry(unsigned int) const + 124
19 swift-frontend           0x0000000105db6780 (anonymous namespace)::DeclChecker::visit(swift::Decl*) + 2232
20 swift-frontend           0x0000000105db5eb0 swift::TypeChecker::typeCheckDecl(swift::Decl*) + 116
21 swift-frontend           0x0000000105e3aae8 swift::ASTVisitor<(anonymous namespace)::StmtChecker, void, swift::Stmt*, void, void, void, void>::visit(swift::Stmt*) + 140
22 swift-frontend           0x0000000105e39314 bool (anonymous namespace)::StmtChecker::typeCheckStmt<swift::BraceStmt>(swift::BraceStmt*&) + 136
23 swift-frontend           0x0000000105e38c14 (anonymous namespace)::StmtChecker::typeCheckBody(swift::BraceStmt*&) + 32
24 swift-frontend           0x0000000105e38914 swift::TypeCheckFunctionBodyRequest::evaluate(swift::Evaluator&, swift::AbstractFunctionDecl*) const + 1088
25 swift-frontend           0x000000010619fbec swift::TypeCheckFunctionBodyRequest::OutputType swift::Evaluator::getResultUncached<swift::TypeCheckFunctionBodyRequest, swift::TypeCheckFunctionBodyRequest::OutputType swift::evaluateOrDefault<swift::TypeCheckFunctionBodyRequest>(swift::Evaluator&, swift::TypeCheckFunctionBodyRequest, swift::TypeCheckFunctionBodyRequest::OutputType)::'lambda'()>(swift::TypeCheckFunctionBodyRequest const&, swift::TypeCheckFunctionBodyRequest::OutputType swift::evaluateOrDefault<swift::TypeCheckFunctionBodyRequest>(swift::Evaluator&, swift::TypeCheckFunctionBodyRequest, swift::TypeCheckFunctionBodyRequest::OutputType)::'lambda'()) + 224
26 swift-frontend           0x0000000106121dfc swift::AbstractFunctionDecl::getTypecheckedBody() const + 112
27 swift-frontend           0x000000010623dd3c swift::SourceFile::typeCheckDelayedFunctions() + 96
28 swift-frontend           0x0000000105e818d0 swift::TypeCheckSourceFileRequest::evaluate(swift::Evaluator&, swift::SourceFile*) const + 228
29 swift-frontend           0x0000000105e83288 swift::TypeCheckSourceFileRequest::OutputType swift::Evaluator::getResultUncached<swift::TypeCheckSourceFileRequest, swift::TypeCheckSourceFileRequest::OutputType swift::evaluateOrDefault<swift::TypeCheckSourceFileRequest>(swift::Evaluator&, swift::TypeCheckSourceFileRequest, swift::TypeCheckSourceFileRequest::OutputType)::'lambda'()>(swift::TypeCheckSourceFileRequest const&, swift::TypeCheckSourceFileRequest::OutputType swift::evaluateOrDefault<swift::TypeCheckSourceFileRequest>(swift::Evaluator&, swift::TypeCheckSourceFileRequest, swift::TypeCheckSourceFileRequest::OutputType)::'lambda'()) + 216
30 swift-frontend           0x0000000105e817c4 swift::performTypeChecking(swift::SourceFile&) + 84
31 swift-frontend           0x0000000104edfd7c bool llvm::function_ref<bool (swift::SourceFile&)>::callback_fn<swift::CompilerInstance::performSema()::$_0>(long, swift::SourceFile&) + 16
32 swift-frontend           0x0000000104ed94f8 swift::CompilerInstance::forEachFileToTypeCheck(llvm::function_ref<bool (swift::SourceFile&)>) + 76
33 swift-frontend           0x0000000104ed948c swift::CompilerInstance::performSema() + 76
34 swift-frontend           0x0000000104cb7790 withSemanticAnalysis(swift::CompilerInstance&, swift::FrontendObserver*, llvm::function_ref<bool (swift::CompilerInstance&)>, bool) + 60
35 swift-frontend           0x0000000104cacfbc performCompile(swift::CompilerInstance&, int&, swift::FrontendObserver*) + 700
36 swift-frontend           0x0000000104cac6dc swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) + 2392
37 swift-frontend           0x0000000104a8e238 swift::mainEntry(int, char const**) + 3052
38 dyld                     0x000000019cc38274 start + 2840

Expected behavior

Invalid program diagnosed properly

Environment

Swift version 6.1-dev (LLVM 42f3e8ef873e24d, Swift 0c8afd3)
Target: arm64-apple-macosx15.0

Additional information

No response

[asl]

So, the typechecker starts to typecheck the call let gradient = vwpb.pullback(1.0):

---Initial constraints for the given expression---
(call_expr type="S.TangentVector" location=validate.swift:6:25 range=[validate.swift:6:20 - line:6:37] isolation_crossing="none"
  (unresolved_dot_expr type="(T.TangentVector) -> S.TangentVector" location=validate.swift:6:25 range=[validate.swift:6:20 - line:6:25] field="pullback" function_ref=single apply
    (declref_expr type="(value: T, pullback: (T.TangentVector) -> S.TangentVector)" location=validate.swift:6:20 range=[validate.swift:6:20 - line:6:20] decl="validate.(file).validate(function:with:at:)[email protected]:4:9" function_ref=unapplied))
  (argument_list
    (argument
      (float_literal_expr type="$T2" location=validate.swift:6:34 range=[validate.swift:6:34 - line:6:34] value="1.0" builtin_initializer="**NULL**" initializer="**NULL**"))))

And solution is:

---Solution---
Fixed score: [component: applied fix(s), value: 2]
Type variables:
  $T0 as (value: T, pullback: (T.TangentVector) -> S.TangentVector) @ locator@0x13e83a200 [[email protected]:6:20]
  $T1 as (T.TangentVector) -> S.TangentVector @ locator@0x13e83a278 [[email protected]:6:25 → member]
  $T2 as Double @ locator@0x13e83a348 [[email protected]:6:34]
  $T3 as S.TangentVector @ locator@0x13e83a418 [[email protected]:6:25 → function result]
Overload choices:
  locator@0x13e83a200 [[email protected]:6:20] with validate.(file).validate(function:with:at:)[email protected]:4:9 as vwpb: (value: T, pullback: (T.TangentVector) -> S.TangentVector)
  locator@0x13e83a278 [[email protected]:6:25 → member] with tuple (value: T, pullback: (T.TangentVector) -> S.TangentVector) index 1
Trailing closure matching:
  locator@0x13e83a4d8 [[email protected]:6:25 → apply argument]: forward
  locator@0x13e83a250 [[email protected]:6:25 → apply argument]: forward
Fixes:
  [fix: allow argument to parameter type conversion mismatch] @ locator@0x13e83a500 [[email protected]:6:25 → apply argument → comparing call argument #0 to parameter #0]

And it seems that the crash happens inside AllowArgumentMismatch::diagnose. Here from type is:

(struct_type decl="Swift.(file).Double")

and to type is:

(primary_archetype_type address=0x13e4a3ab8 conforms_to="Swift.(file).AdditiveArithmetic" conforms_to="_Differentiation.(file).Differentiable" name="T.TangentVector"
  (interface_type=dependent_member_type assoc_type="_Differentiation.(file).Differentiable.TangentVector"
    (base=generic_type_param_type depth=0 index=1 name="T" param_kind=type)))

So, Solution::resolveInterfaceType cannot handle

(function_type escaping
  (input=function_params num_params=1
    (param
      (primary_archetype_type address=0x13acb34b8 conforms_to="Swift.(file).AdditiveArithmetic" conforms_to="_Differentiation.(file).Differentiable" name="T.TangentVector"
        (interface_type=dependent_member_type assoc_type="_Differentiation.(file).Differentiable.TangentVector"
          (base=generic_type_param_type depth=0 index=1 name="T" param_kind=type)))))
  (output=primary_archetype_type address=0x13acb3440 conforms_to="Swift.(file).AdditiveArithmetic" conforms_to="_Differentiation.(file).Differentiable" name="S.TangentVector"
    (interface_type=dependent_member_type assoc_type="_Differentiation.(file).Differentiable.TangentVector"
      (base=generic_type_param_type depth=0 index=0 name="S" param_kind=type))))

[asl]

It seems that conformance to FloatingPoint is lost somehow? As then we will have T == T.TangentVector plus corresponding .init.