Frontend: Add -disable-experimental-associated-type-inference flag

Author: slavapestov

include/swift/Basic/Features.def

@@ -151,7 +151,6 @@ EXPERIMENTAL_FEATURE(MoveOnlyTuples, true)
 EXPERIMENTAL_FEATURE(MoveOnlyPartialConsumption, true)
 
 EXPERIMENTAL_FEATURE(OneWayClosureParameters, false)
-EXPERIMENTAL_FEATURE(TypeWitnessSystemInference, false)
 EXPERIMENTAL_FEATURE(LayoutPrespecialization, true)
 
 EXPERIMENTAL_FEATURE(AccessLevelOnImport, true)

include/swift/Basic/LangOptions.h

@@ -585,6 +585,9 @@ namespace swift {
     /// Enable warnings for redundant requirements in generic signatures.
     bool WarnRedundantRequirements = false;
 
+    /// Enable experimental associated type inference improvements.
+    bool EnableExperimentalAssociatedTypeInference = false;
+
     /// Enables dumping type witness systems from associated type inference.
     bool DumpTypeWitnessSystems = false;
 

include/swift/Option/FrontendOptions.td

@@ -654,7 +654,11 @@ def disable_experimental_string_processing :
 
 def enable_experimental_associated_type_inference :
   Flag<["-"], "enable-experimental-associated-type-inference">,
-  HelpText<"Enable experimental associated type inference via type witness systems">;
+  HelpText<"Enable experimental associated type inference improvements">;
+
+def disable_experimental_associated_type_inference :
+  Flag<["-"], "disable-experimental-associated-type-inference">,
+  HelpText<"Disable experimental associated type inference improvements">;
 
 def disable_availability_checking : Flag<["-"],
   "disable-availability-checking">,

lib/AST/ASTPrinter.cpp

@@ -3479,10 +3479,6 @@ static bool usesFeatureOneWayClosureParameters(Decl *decl) {
   return false;
 }
 
-static bool usesFeatureTypeWitnessSystemInference(Decl *decl) {
-  return false;
-}
-
 static bool usesFeatureOpaqueTypeErasure(Decl *decl) {
   return false;
 }

lib/AST/ProtocolConformance.cpp

@@ -548,7 +548,7 @@ NormalProtocolConformance::getAssociatedConformance(Type assocType,
   forEachAssociatedConformance(
       [&](Type t, ProtocolDecl *p, unsigned index) {
         if (t->isEqual(assocType) && p == protocol) {
-          if (!ctx.LangOpts.hasFeature(Feature::TypeWitnessSystemInference)) {
+          if (!ctx.LangOpts.EnableExperimentalAssociatedTypeInference) {
             // Fill in the signature conformances, if we haven't done so yet.
             if (!hasComputedAssociatedConformances()) {
               const_cast<NormalProtocolConformance *>(this)

lib/Frontend/CompilerInvocation.cpp

@@ -910,8 +910,6 @@ static bool ParseLangArgs(LangOptions &Opts, ArgList &Args,
   }
   if (Args.hasArg(OPT_experimental_one_way_closure_params))
     Opts.Features.insert(Feature::OneWayClosureParameters);
-  if (Args.hasArg(OPT_enable_experimental_associated_type_inference))
-    Opts.Features.insert(Feature::TypeWitnessSystemInference);
   if (Args.hasArg(OPT_enable_experimental_forward_mode_differentiation))
     Opts.Features.insert(Feature::ForwardModeDifferentiation);
   if (Args.hasArg(OPT_enable_experimental_additive_arithmetic_derivation))
@@ -1351,6 +1349,11 @@ static bool ParseLangArgs(LangOptions &Opts, ArgList &Args,
   if (Args.hasArg(OPT_warn_redundant_requirements))
     Opts.WarnRedundantRequirements = true;
 
+  if (Args.hasArg(OPT_enable_experimental_associated_type_inference))
+    Opts.EnableExperimentalAssociatedTypeInference = true;
+  if (Args.hasArg(OPT_disable_experimental_associated_type_inference))
+    Opts.EnableExperimentalAssociatedTypeInference = false;
+
   Opts.DumpTypeWitnessSystems = Args.hasArg(OPT_dump_type_witness_systems);
 
   for (auto &block: FrontendOpts.BlocklistConfigFilePaths)

lib/Sema/TypeCheckProtocolInference.cpp

@@ -1374,7 +1374,7 @@ AssociatedTypeDecl *AssociatedTypeInference::inferAbstractTypeWitnesses(
   // not resolve otherwise.
   llvm::SmallVector<AbstractTypeWitness, 2> abstractTypeWitnesses;
 
-  if (ctx.LangOpts.hasFeature(Feature::TypeWitnessSystemInference)) {
+  if (ctx.LangOpts.EnableExperimentalAssociatedTypeInference) {
     TypeWitnessSystem system(unresolvedAssocTypes);
     collectAbstractTypeWitnesses(system, unresolvedAssocTypes);
 

test/decl/protocol/req/associated_type_inference_fixed_type.swift

@@ -1,4 +1,4 @@
-// RUN: %target-typecheck-verify-swift
+// RUN: %target-typecheck-verify-swift -disable-experimental-associated-type-inference
 
 protocol P1 where A == Never {
   associatedtype A

test/decl/protocol/req/associated_type_inference_stdlib.swift

@@ -1,5 +1,5 @@
 // RUN: %target-typecheck-verify-swift -enable-experimental-associated-type-inference
-// RUN: %target-typecheck-verify-swift
+// RUN: %target-typecheck-verify-swift -disable-experimental-associated-type-inference
 
 // We would fail here when Indices was explicitly specified, as in X2.
 

test/decl/protocol/req/associated_type_inference_stdlib_2.swift

@@ -1,5 +1,5 @@
 // RUN: %target-typecheck-verify-swift -enable-experimental-associated-type-inference
-// RUN: not %target-typecheck-verify-swift
+// RUN: not %target-typecheck-verify-swift -disable-experimental-associated-type-inference
 
 protocol IP {
   associatedtype E

test/decl/protocol/req/rdar118998138.swift

@@ -1,5 +1,5 @@
 // RUN: %target-typecheck-verify-swift -enable-experimental-associated-type-inference
-// RUN: not %target-typecheck-verify-swift
+// RUN: not %target-typecheck-verify-swift -disable-experimental-associated-type-inference
 
 public protocol FakeCopyable {}
 

test/decl/protocol/req/rdar90402522.swift

@@ -1,5 +1,5 @@
 // RUN: %target-typecheck-verify-swift -enable-experimental-associated-type-inference
-// RUN: %target-typecheck-verify-swift
+// RUN: %target-typecheck-verify-swift -disable-experimental-associated-type-inference
 
 public typealias A = UInt32
 

validation-test/compiler_crashers_2_fixed/issue-53793.swift

@@ -1,4 +1,4 @@
-// RUN: %target-swift-frontend -verify -emit-ir %s
+// RUN: %target-swift-frontend -disable-experimental-associated-type-inference -verify -emit-ir %s
 
 // Works with experimental associated type inference.
 // RUN: %target-swift-frontend -enable-experimental-associated-type-inference -emit-ir %s

validation-test/compiler_crashers_2_fixed/rdar110806272.swift

@@ -1,5 +1,7 @@
 // RUN: not %target-swift-frontend -typecheck %s -enable-experimental-associated-type-inference
 
+// This code is invalid, but we shouldn't crash.
+
 struct SyntaxCollectionIterator<E: SyntaxProtocol>: IteratorProtocol {
   typealias Element = E
 }