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Fixing async main resolution #42142

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Merged
merged 4 commits into from
Apr 4, 2022
Merged

Fixing async main resolution #42142

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da0a331
Add `-async-main` flag to favor asynchronous main
etcwilde Apr 1, 2022
943812c
Update main resolution tests
etcwilde Apr 1, 2022
a427c05
Appease Windowz
etcwilde Apr 1, 2022
2eb8011
Merge branch 'main' into ewilde/async-main-resolution
etcwilde Apr 2, 2022
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3 changes: 3 additions & 0 deletions include/swift/Basic/LangOptions.h
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Expand Up @@ -209,6 +209,9 @@ namespace swift {
/// Emit a remark after loading a module.
bool EnableModuleLoadingRemarks = false;

/// Resolve main function as though it were called from an async context
bool EnableAsyncMainResolution = false;

///
/// Support for alternate usage modes
///
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4 changes: 4 additions & 0 deletions include/swift/Option/Options.td
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Expand Up @@ -270,6 +270,10 @@ def pch_output_dir: Separate<["-"], "pch-output-dir">,
Flags<[FrontendOption, HelpHidden, ArgumentIsPath]>,
HelpText<"Directory to persist automatically created precompiled bridging headers">;

def async_main: Flag<["-"], "async-main">,
Flags<[FrontendOption]>,
HelpText<"Resolve main function as if it were called from an asynchronous context">;

// FIXME: Unhide this once it doesn't depend on an output file map.
def incremental : Flag<["-"], "incremental">,
Flags<[NoInteractiveOption, HelpHidden, DoesNotAffectIncrementalBuild]>,
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4 changes: 4 additions & 0 deletions include/swift/Sema/ConstraintSystem.h
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Expand Up @@ -1497,6 +1497,10 @@ enum class ConstraintSystemFlags {
/// calling conventions, say due to Clang attributes such as
/// `__attribute__((ns_consumed))`.
UseClangFunctionTypes = 0x80,

/// When set, nominal typedecl contexts are asynchronous contexts.
/// This is set while searching for the main function
ConsiderNominalTypeContextsAsync = 0x100,
};

/// Options that affect the constraint system as a whole.
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8 changes: 6 additions & 2 deletions include/swift/Sema/IDETypeChecking.h
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Expand Up @@ -21,6 +21,7 @@

#include "swift/AST/Identifier.h"
#include "swift/Basic/SourceLoc.h"
#include "swift/Basic/OptionSet.h"
#include <memory>
#include <tuple>

Expand Down Expand Up @@ -50,6 +51,8 @@ namespace swift {
class ConstraintSystem;
class Solution;
class SolutionApplicationTarget;
enum class ConstraintSystemFlags;
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While this makes me slightly uncomfortable, if there is ever a size mismatch between the forward declaration and the full definition with enum members, there is a compile-time error.

e.g.

swift/include/swift/Sema/IDETypeChecking.h:54:14: error: enumeration redeclared with different underlying type 'long' (was 'int')
  enum class ConstraintSystemFlags : long;
             ^
swift/include/swift/Sema/ConstraintSystem.h:1453:12: note: previous declaration is here
enum class ConstraintSystemFlags {
           ^

using ConstraintSystemOptions = OptionSet<ConstraintSystemFlags>;
}

/// Typecheck binding initializer at \p bindingIndex.
Expand Down Expand Up @@ -93,8 +96,9 @@ namespace swift {
/// Unlike other member lookup functions, \c swift::resolveValueMember()
/// should be used when you want to look up declarations with the same name as
/// one you already have.
ResolvedMemberResult resolveValueMember(DeclContext &DC, Type BaseTy,
DeclName Name);
ResolvedMemberResult
resolveValueMember(DeclContext &DC, Type BaseTy, DeclName Name,
constraints::ConstraintSystemOptions Options = {});

/// Given a type and an extension to the original type decl of that type,
/// decide if the extension has been applied, i.e. if the requirements of the
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1 change: 1 addition & 0 deletions lib/Driver/ToolChains.cpp
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Expand Up @@ -299,6 +299,7 @@ void ToolChain::addCommonFrontendArgs(const OutputInfo &OI,
inputArgs.AddLastArg(arguments, options::OPT_access_notes_path);
inputArgs.AddLastArg(arguments, options::OPT_library_level);
inputArgs.AddLastArg(arguments, options::OPT_enable_regex_literals);
inputArgs.AddLastArg(arguments, options::OPT_async_main);

// Pass on any build config options
inputArgs.AddAllArgs(arguments, options::OPT_D);
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2 changes: 2 additions & 0 deletions lib/Frontend/CompilerInvocation.cpp
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Expand Up @@ -489,6 +489,8 @@ static bool ParseLangArgs(LangOptions &Opts, ArgList &Args,
Diags.diagnose(SourceLoc(), diag::warn_flag_deprecated,
"-enable-experimental-async-top-level");

Opts.EnableAsyncMainResolution = Args.hasArg(OPT_async_main);

Opts.DiagnoseInvalidEphemeralnessAsError |=
Args.hasArg(OPT_enable_invalid_ephemeralness_as_error);

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5 changes: 3 additions & 2 deletions lib/Sema/CSGen.cpp
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Expand Up @@ -4421,9 +4421,10 @@ getMemberDecls(InterestedMemberKind Kind) {
}

ResolvedMemberResult
swift::resolveValueMember(DeclContext &DC, Type BaseTy, DeclName Name) {
swift::resolveValueMember(DeclContext &DC, Type BaseTy, DeclName Name,
ConstraintSystemOptions Options) {
ResolvedMemberResult Result;
ConstraintSystem CS(&DC, None);
ConstraintSystem CS(&DC, Options);

// Look up all members of BaseTy with the given Name.
MemberLookupResult LookupResult = CS.performMemberLookup(
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5 changes: 5 additions & 0 deletions lib/Sema/ConstraintSystem.cpp
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Expand Up @@ -2894,6 +2894,11 @@ bool ConstraintSystem::isAsynchronousContext(DeclContext *dc) {
FunctionType::ExtInfo()).isAsync();
}

if (Options.contains(
ConstraintSystemFlags::ConsiderNominalTypeContextsAsync) &&
isa<NominalTypeDecl>(dc))
return true;

return false;
}

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8 changes: 7 additions & 1 deletion lib/Sema/TypeCheckAttr.cpp
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Expand Up @@ -2171,8 +2171,14 @@ SynthesizeMainFunctionRequest::evaluate(Evaluator &evaluator,
// mainType.main() from the entry point, and that would require fully
// type-checking the call to mainType.main().

constraints::ConstraintSystemOptions lookupOptions;
if (context.LangOpts.EnableAsyncMainResolution)
lookupOptions |=
constraints::ConstraintSystemFlags::ConsiderNominalTypeContextsAsync;

auto resolution = resolveValueMember(
*declContext, nominal->getInterfaceType(), context.Id_main);
*declContext, nominal->getInterfaceType(), context.Id_main,
lookupOptions);
FuncDecl *mainFunction =
resolveMainFunctionDecl(declContext, resolution, context);
if (!mainFunction) {
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44 changes: 24 additions & 20 deletions test/Concurrency/async_main_resolution.swift
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@@ -1,24 +1,32 @@
// Non-apple platforms don't need to worry about the version number as much
// because they can pull in the concurrency libraries with the swift
// installation.

// async main is nested deeper in protocols than sync, use sync
// sync main is nested deeper in protocols than async, use async
// async and sync are same level, use async

// REQUIRES: rdar89500797

// REQUIRES: concurrency
// UNSUPPORTED: VENDOR=apple

// Async is deeper in the protocol chain from `MyMain`, use sync
// RUN: %target-swift-frontend -DASYNC_NESTED -DINHERIT_SYNC -typecheck -dump-ast -parse-as-library %s | %FileCheck %s --check-prefix=CHECK-IS-SYNC

// Sync is deeper in the protocol chain from `MyMain`, use async
// RUN: %target-swift-frontend -typecheck -dump-ast -parse-as-library %s | %FileCheck %s --check-prefix=CHECK-IS-ASYNC

// Async and sync are the same level, use async
// RUN: %target-swift-frontend -DBOTH -DINHERIT_SYNC -typecheck -dump-ast -parse-as-library %s | %FileCheck %s --check-prefix=CHECK-IS-ASYNC
// ASYNC_NESTED: async is nested more deeply than sync main in protocol chain
// NO_ASYNC: no async main function
// NO_SYNC: no sync main function
// BOTH: MainProtocol has both sync and async main
// INHERIT_SYNC: main type directly conforms to synchronous main protocol

// | async flag | has async main | has sync main | both | inherits sync | nested async | Result | Run |
// | | | | | | | Error | RUN: not %target-swift-frontend -disable-availability-checking -DNO_ASYNC -DNO_SYNC -parse-as-library -typecheck -dump-ast %s 2>&1 | %FileCheck %s --check-prefix=CHECK-IS-ERROR
// | | x | | | | | Async Main | RUN: %target-swift-frontend -disable-availability-checking -DNO_SYNC -parse-as-library -typecheck -dump-ast %s | %FileCheck %s --check-prefix=CHECK-IS-ASYNC
// | x | | x | | | | Sync Main | RUN: %target-swift-frontend -disable-availability-checking -DNO_ASYNC -async-main -parse-as-library -typecheck -dump-ast %s | %FileCheck %s --check-prefix=CHECK-IS-SYNC
// | x | x | x | | | | Async Main | RUN: %target-swift-frontend -disable-availability-checking -async-main -parse-as-library -typecheck -dump-ast %s | %FileCheck %s --check-prefix=CHECK-IS-ASYNC
// | | x | x | | | | Sync Main | RUN: %target-swift-frontend -disable-availability-checking -parse-as-library -typecheck -dump-ast %s | %FileCheck %s --check-prefix=CHECK-IS-SYNC
// | | x | x | | | x | Async Main | RUN: %target-swift-frontend -disable-availability-checking -DASYNC_NESTED -parse-as-library -typecheck -dump-ast %s | %FileCheck %s --check-prefix=CHECK-IS-ASYNC
// | | x | x | | x | x | Sync Main | RUN: %target-swift-frontend -disable-availability-checking -DINHERIT_SYNC -DASYNC_NESTED -parse-as-library -typecheck -dump-ast %s | %FileCheck %s --check-prefix=CHECK-IS-SYNC
// | x | x | x | | x | x | Async Main | RUN: %target-swift-frontend -disable-availability-checking -DINHERIT_SYNC -DASYNC_NESTED -async-main -parse-as-library -typecheck -dump-ast %s | %FileCheck %s --check-prefix=CHECK-IS-ASYNC
// | x | | x | | x | x | Sync Main | RUN: %target-swift-frontend -disable-availability-checking -DNO_ASYNC -DINHERIT_SYNC -DASYNC_NESTED -async-main -parse-as-library -typecheck -dump-ast %s | %FileCheck %s --check-prefix=CHECK-IS-SYNC
// | | | x | x | | | Sync Main | RUN: %target-swift-frontend -disable-availability-checking -DBOTH -DNO_ASYNC -parse-as-library -typecheck -dump-ast %s | %FileCheck %s --check-prefix=CHECK-IS-SYNC
// | x | | x | x | | | Async Main | RUN: %target-swift-frontend -disable-availability-checking -DBOTH -DNO_ASYNC -async-main -parse-as-library -typecheck -dump-ast %s | %FileCheck %s --check-prefix=CHECK-IS-ASYNC

// tldr;
// If async flag is set, will pick an asynchronous main function if one is available and related. If none exist, will fall back on synchronous main.
// If async flag is not set, will pick a asynchronous main function if one is available and related. If none exist, will fall back on an asynchronous main
// If neither are available; error

#if ASYNC_NESTED
protocol AsyncMainProtocol { }
Expand Down Expand Up @@ -55,8 +63,6 @@ extension MainProtocol {
@main struct MyMain : AsyncMainProtocol {}
#endif



// CHECK-IS-SYNC-LABEL: "MyMain" interface type='MyMain.Type'
// CHECK-IS-SYNC: (func_decl implicit "$main()" interface type='(MyMain.Type) -> () -> ()'
// CHECK-IS-SYNC: (declref_expr implicit type='(MyMain.Type) -> () -> ()'
Expand All @@ -65,6 +71,4 @@ extension MainProtocol {
// CHECK-IS-ASYNC: (func_decl implicit "$main()" interface type='(MyMain.Type) -> () async -> ()'
// CHECK-IS-ASYNC: (declref_expr implicit type='(MyMain.Type) -> () async -> ()'

// CHECK-IS-ERROR: error: 'MyMain' is annotated with @main and must provide a main static function of type () -> Void or () throws -> Void

// CHECK-IS-ERROR-ASYNC: error: 'MyMain' is annotated with @main and must provide a main static function of type () -> Void, () throws -> Void, () async -> Void, or () async throws -> Void
// CHECK-IS-ERROR: error: 'MyMain' is annotated with @main and must provide a main static function of type {{\(\) -> Void or \(\) throws -> Void|\(\) -> Void, \(\) throws -> Void, \(\) async -> Void, or \(\) async throws -> Void}}
95 changes: 0 additions & 95 deletions test/Concurrency/async_main_resolution_macos.swift
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