Merge pull request #4587 from swiftwasm/main

[pull] swiftwasm from main

CHANGELOG.md

@@ -5,6 +5,86 @@ _**Note:** This is in reverse chronological order, so newer entries are added to
 
 ## Swift 5.7
 
+* [SE-0309][]:
+
+  Protocols with associated types and `Self` requirements can now be used as the
+  types of values with the `any` keyword.
+
+  Protocol methods that return associated types can be called on an `any` type;
+  the result is type-erased to the associated type's upper bound, which is another
+  `any` type having the same constraints as the associated type. For example:
+
+  ```swift
+    protocol Surface {...}
+
+    protocol Solid {
+      associatedtype SurfaceType: Surface
+      func boundary() -> SurfaceType
+    }
+
+    let solid: any Solid = ...
+
+    // Type of 'boundary' is 'any Surface'
+    let boundary = solid.boundary()
+  ```
+
+  Protocol methods that take an associated type or `Self` cannot be used with `any`,
+  however in conjunction with [SE-0352][], you can pass the `any` type to a function
+  taking a generic parameter constrained to the protocol. Within the generic context,
+  type relationships are explicit and all protocol methods can be used.
+
+* [SE-0346][]:
+
+  Protocols can now declare a list of one or more primary associated types:
+
+  ```swift
+    protocol Graph<Vertex, Edge> {
+      associatedtype Vertex
+      associatedtype Edge
+    }
+  ```
+
+  A protocol-constrained type like `Graph<Int>` can now be written anywhere that
+  expects the right-hand side of a protocol conformance requirement:
+
+  ```swift
+    func shortestPath<V, E>(_: some Graph<V>, from: V, to: V) -> [E]
+
+    extension Graph<Int> {...}
+
+    func build() -> some Graph<String> {}
+  ```
+
+  A protocol-constrained type is equivalent to a conformance requirement to the protocol
+  itself together with a same-type requirement constraining the primary associated type.
+  The first two examples above are equivalent to the following:
+
+  ```swift
+    func shortestPath<V, E, G>(_: G, from: V, to: V) -> [E]
+      where G: Graph, G.Vertex == V, G.Edge == V
+
+    extension Graph where Vertex == Int {...}
+  ```
+
+  The `build()` function returning `some Graph<String>` cannot be written using a `where`
+  clause; this is an example of a constrained opaque result type, which could not be written
+  before.
+
+* [SE-0353][]:
+
+  Further generalizing the above, protocol-constrained types can also be used with `any`:
+
+  ```swift
+    func findBestGraph(_: [any Graph<Int>]) -> any Graph<Int> {...}
+  ```
+
+* [SE-0358][]:
+
+  Various protocols in the standard library now declare primary associated types, for
+  example `Sequence` and `Collection` declare a single primary associated type `Element`.
+  For example, this allows writing down the types `some Collection<Int>` and
+  `any Collection<Int>`.
+
 * References to `optional` methods on a protocol metatype, as well as references to dynamically looked up methods on the `AnyObject` metatype are now supported. These references always have the type of a function that accepts a single argument and returns an optional value of function type:
 
   ```swift
@@ -9261,6 +9341,7 @@ Swift 1.0
 [SE-0300]: <https://github.com/apple/swift-evolution/blob/main/proposals/0300-continuation.md>
 [SE-0302]: <https://github.com/apple/swift-evolution/blob/main/proposals/0302-concurrent-value-and-concurrent-closures.md>
 [SE-0306]: <https://github.com/apple/swift-evolution/blob/main/proposals/0306-actors.md>
+[SE-0309]: <https://github.com/apple/swift-evolution/blob/main/proposals/0309-unlock-existential-types-for-all-protocols.md>
 [SE-0310]: <https://github.com/apple/swift-evolution/blob/main/proposals/0310-effectful-readonly-properties.md>
 [SE-0311]: <https://github.com/apple/swift-evolution/blob/main/proposals/0311-task-locals.md>
 [SE-0313]: <https://github.com/apple/swift-evolution/blob/main/proposals/0313-actor-isolation-control.md>
@@ -9283,9 +9364,12 @@ Swift 1.0
 [SE-0341]: <https://github.com/apple/swift-evolution/blob/main/proposals/0341-opaque-parameters.md>
 [SE-0343]: <https://github.com/apple/swift-evolution/blob/main/proposals/0343-top-level-concurrency.md>
 [SE-0345]: <https://github.com/apple/swift-evolution/blob/main/proposals/0345-if-let-shorthand.md>
+[SE-0346]: <https://github.com/apple/swift-evolution/blob/main/proposals/0346-light-weight-same-type-syntax.md>
 [SE-0347]: <https://github.com/apple/swift-evolution/blob/main/proposals/0347-type-inference-from-default-exprs.md>
 [SE-0349]: <https://github.com/apple/swift-evolution/blob/main/proposals/0349-unaligned-loads-and-stores.md>
 [SE-0352]: <https://github.com/apple/swift-evolution/blob/main/proposals/0352-implicit-open-existentials.md>
+[SE-0353]: <https://github.com/apple/swift-evolution/blob/main/proposals/0353-constrained-existential-types.md>
+[SE-0358]: <https://github.com/apple/swift-evolution/blob/main/proposals/0358-primary-associated-types-in-stdlib.md>
 
 [SR-75]: <https://bugs.swift.org/browse/SR-75>
 [SR-106]: <https://bugs.swift.org/browse/SR-106>

docs/DevelopmentTips.md

@@ -20,6 +20,25 @@ Going further, for various reasons the standard library has lots of warnings. Th
 
 Copy the invocation that has  ` -o <build-path>/swift-macosx-x86_64/stdlib/public/core/iphonesimulator/i386/Swift.o`, so that we can perform the actual call to swiftc ourselves. Tack on `-suppress-warnings` at the end, and now we have the command to just build `Swift.o` for i386 while only displaying the actual errors.
 
+### Choosing the bootstrapping mode
+By default, the compiler builds with the `boostrapping-with-hostlibs` (macOS) or `bootstrapping` (Linux) bootstrapping mode. To speed up local development it's recommended to build with the `hosttools` mode: `utils/build-script --bootstrapping=hosttools`.
+
+It requires a recently new swift toolchain to be installed on your build machine. On macOS this comes with your Xcode installation.
+
+Not that changing the bootstrapping mode needs a reconfiguration.
+
+### Working with two build directories
+For developing and debugging you are probably building a debug configuration of swift. But it's often beneficial to also build a release-assert configuration in parallel (`utils/build-script -R`).
+
+The standard library takes very long to build with a debug compiler. It's much faster to build everything (including the standard library) with a release compiler and only the swift-frontend (with `ninja swift-frontend`) in debug. Then copy the release-built standard library to the debug build:
+```
+src=/path/to/build/Ninja-ReleaseAssert/swift-macosx-x86_64
+dst=/path/to/build/Ninja-DebugAssert/swift-macosx-x86_64
+cp -r $src/stdlib $dst/
+cp -r $src/lib/swift/macosx $dst/lib/swift/
+cp -r $src/lib/swift/shims $dst/lib/swift/
+```
+
 ### Use sccache to cache build artifacts
 
 Compilation times for the compiler and the standard library can be agonizing, especially for cold builds. This is particularly painful if
@@ -65,3 +84,29 @@ For example, to have `build-script` spawn only one link job at a time, we can in
 ```
 build-script --llvm-cmake-options==-DLLVM_PARALLEL_LINK_JOBS=1 --swift-cmake-options=-DSWIFT_PARALLEL_LINK_JOBS=1
 ```
+
+## Using ninja with Xcode
+
+Although it's possible to build the swift compiler entirely with Xcode (`--xcode`), often it's better to build with _ninja_ and use Xcode for editing and debugging.
+This is very convenient because you get the benefits of the ninja build system and all the benefits of the Xcode IDE, like code completion, refactoring, debugging, etc.
+
+To setup this environment a few steps are necessary:
+* Create a new workspace.
+* Create Xcode projects for LLVM and Swift with `utils/build-script --skip-build --xcode --skip-early-swift-driver`. Beside configuring, this needs to build a few LLVM files which are needed to configure the swift project.
+* Add the generated LLVM and Swift projects to your workspace. They can be found in the build directories `build/Xcode-DebugAssert/llvm-macosx-x86_64/LLVM.xcodeproj` and `build/Xcode-DebugAssert/swift-macosx-x86_64/Swift.xcodeproj`.
+* Add the `swift/SwiftCompilerSources` package to the workspace.
+* Create a new empty project `build-targets` (or however you want to name it) in the workspace, using the "External Build System" template.
+* For each compiler tool you want to build (`swift-frontend`, `sil-opt`, etc.), add an "External Build System" target to the `build-targets` project.
+* In the "Info" section of the target configuration, set:
+    * the _Build Tool_ to the full path of the `ninja` command
+    * the _Argument_ to the tool name (e.g. `swift-frontend`)
+    * the _Directory_ to the ninja swift build directory, e.g. `/absolute/path/to/build/Ninja-DebugAssert/swift-macosx-x86_64`. For debugging to work, this has to be a debug build of course.
+* For each target, create a new scheme:
+    * In the _Build_ section add the corresponding build target that you created before.
+    * In the _Run/Info_ section select the built _Executable_ in the build directory (e.g. `/absolute/path/to/build/Ninja-DebugAssert/swift-macosx-x86_64/bin/swift-frontend`).
+    * In the _Run/Arguments_ section you can set the command line arguments with which you want to run the compiler tool.
+    * In the _Run/Options_ section you can set the working directory for debugging.
+
+Now you are all set. You can build and debug like with a native Xcode project.
+
+If the project structure changes, e.g. new source files are added or deleted, you just have to re-create the LLVM and Swift projects with `utils/build-script --skip-build --xcode --skip-early-swift-driver`.

docs/HowToGuides/GettingStarted.md

@@ -282,6 +282,8 @@ The additional flexibility comes with two issues: (1) consuming much more disk
 space and (2) you need to maintain the two builds in sync, which needs extra
 care when moving across branches.
 
+It is even possible to integrate the Ninja build into Xcode. For details on how to set this up see [Using Ninja with Xcode in DevelopmentTips.md](/docs/DevelopmentTips.md#using-ninja-with-xcode).
+
 ### Troubleshooting build issues
 
 - Double-check that all projects are checked out at the right branches.

include/swift/AST/DiagnosticsClangImporter.def

@@ -118,7 +118,7 @@ WARNING(nonmutating_without_mutable_fields,none,
 ERROR(module_map_not_found, none, "module map file '%0' not found", (StringRef))
 
 WARNING(libstdcxx_not_found, none,
-        "libstdc++ not found for '$0'; C++ stdlib may be unavailable",
+        "libstdc++ not found for '%0'; C++ stdlib may be unavailable",
         (StringRef))
 
 NOTE(macro_not_imported_unsupported_operator, none, "operator not supported in macro arithmetic", ())

include/swift/AST/DiagnosticsSema.def

@@ -4709,6 +4709,9 @@ ERROR(unchecked_not_inheritance_clause,none,
 ERROR(unchecked_not_existential,none,
       "'unchecked' attribute cannot apply to non-protocol type %0", (Type))
 
+ERROR(redundant_any_in_existential,none,
+       "redundant 'any' has no effect on existential type %0",
+       (Type))
 ERROR(any_not_existential,none,
        "'any' has no effect on %select{concrete type|type parameter}0 %1",
        (bool, Type))

include/swift/Parse/SyntaxRegexFallbackLexing.h

@@ -0,0 +1,21 @@
+//===--- SyntaxRegexFallbackLexing.h --------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2022 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+namespace swift {
+/// SwiftSyntax parsing currently doesn't link against
+/// SwiftExperimentalStringProcessing and is thus missing the regex lexing
+/// functions defined in it. This registers a fallback regex-lexing function
+/// implemented in C++ that is sufficient to generate a valid SwiftSyntax tree.
+/// The regex parser registered by this function will accept all regex literals
+/// and is not suited for normal compilation.
+void registerSyntaxFallbackRegexParser();
+} // end namespace swift

include/swift/SIL/BasicBlockUtils.h

@@ -13,8 +13,9 @@
 #ifndef SWIFT_SIL_BASICBLOCKUTILS_H
 #define SWIFT_SIL_BASICBLOCKUTILS_H
 
-#include "swift/SIL/SILValue.h"
 #include "swift/SIL/BasicBlockBits.h"
+#include "swift/SIL/BasicBlockDatastructures.h"
+#include "swift/SIL/SILValue.h"
 #include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallVector.h"
@@ -155,6 +156,81 @@ void findJointPostDominatingSet(
 bool checkDominates(SILBasicBlock *sourceBlock, SILBasicBlock *destBlock);
 #endif
 
+/// Walk depth-first the region backwards reachable from the provided roots
+/// constrained by \p region's \p isInRegion member function.
+///
+/// interface Region {
+///   /// Whether the indicated basic block is within the region of the graph
+///   /// that should be traversed.
+///   bool isInRegion(SILBasicBlock *)
+/// }
+template <typename Region>
+struct SILCFGBackwardDFS {
+  Region &region;
+  ArrayRef<SILBasicBlock *> roots;
+  Optional<SmallVector<SILBasicBlock *, 16>> cachedPostOrder;
+  Optional<BasicBlockSet> cachedVisited;
+
+  SILCFGBackwardDFS(Region &region, ArrayRef<SILBasicBlock *> roots)
+      : region(region), roots(roots) {}
+
+  /// Visit the blocks of the region in post-order.
+  ///
+  /// interface Visitor {
+  ///     /// Visit each block in topological order.
+  ///     void visit(SILBasicBlock *)
+  /// }
+  template <typename Visitor>
+  void visitPostOrder(Visitor &visitor) {
+    if (roots.empty())
+      return;
+    auto *function = roots.front()->getParent();
+    cachedVisited.emplace(function);
+    for (auto *root : roots) {
+      SmallVector<std::pair<SILBasicBlock *, SILBasicBlock::pred_iterator>, 32>
+          stack;
+      if (!region.isInRegion(root))
+        continue;
+      stack.push_back({root, root->pred_begin()});
+      while (!stack.empty()) {
+        while (stack.back().second != stack.back().first->pred_end()) {
+          auto predecessor = *stack.back().second;
+          stack.back().second++;
+          if (!region.isInRegion(predecessor))
+            continue;
+          if (cachedVisited->insert(predecessor))
+            stack.push_back({predecessor, predecessor->pred_begin()});
+        }
+        visitor.visit(stack.back().first);
+        stack.pop_back();
+      }
+    }
+  }
+
+  /// Visit the region in post-order and cache the visited blocks.
+  void cachePostOrder() {
+    if (cachedPostOrder)
+      return;
+    struct Visitor {
+      SILCFGBackwardDFS<Region> &dfs;
+      void visit(SILBasicBlock *block) {
+        dfs.cachedPostOrder->push_back(block);
+      }
+    };
+    cachedPostOrder.emplace();
+    Visitor visitor{*this};
+    visitPostOrder(visitor);
+  }
+
+  /// The region in post-order.
+  ArrayRef<SILBasicBlock *> postOrder() {
+    cachePostOrder();
+    return *cachedPostOrder;
+  };
+
+  /// The region in reverse post-order.
+  auto reversePostOrder() { return llvm::reverse(postOrder()); }
+};
 } // namespace swift
 
 #endif

include/swift/SIL/SILBasicBlock.h

@@ -48,7 +48,7 @@ public SwiftObjectHeader {
   /// A backreference to the containing SILFunction.
   SILFunction *Parent;
 
-  /// PrevList - This is a list of all of the terminator operands that are
+  /// PredList - This is a list of all of the terminator operands that are
   /// branching to this block, forming the predecessor list.  This is
   /// automatically managed by the SILSuccessor class.
   SILSuccessor *PredList = nullptr;