Add a flag to parse serially (#1063)

* Don't parse in parallel

Parsing in parallel is leading to unexpected `EXC_BAD_ACCESS`es in our codebase.  By switching to `compactMap`, the crashes go away.

The specific crash is deep in the internals of `SwiftSyntax`, which leads me to believe that there's some internal global thread-unsafe state that's being shared bewteen parsing instances. Here's an example (abbreviated) stacktrace:
```
#0	0x00000001001209e4 in protocol witness for SyntaxProtocol._syntaxNode.getter in conformance Syntax ()
#1	0x0000000100121ec3 in SyntaxProtocol.raw.getter at /Users/eric_horacek/Library/Developer/Xcode/DerivedData/Sourcery-hibchsafsxkdcjaxxaylrbeyoydh/SourcePackages/checkouts/swift-syntax/Sources/SwiftSyntax/Syntax.swift:129
#2	0x0000000100b85c32 in SimpleTypeIdentifierSyntax.init(_:) at /Users/eric_horacek/Library/Developer/Xcode/DerivedData/Sourcery-hibchsafsxkdcjaxxaylrbeyoydh/SourcePackages/checkouts/swift-syntax/Sources/SwiftSyntax/gyb_generated/syntax_nodes/SyntaxTypeNodes.swift:68
#3	0x0000000100b89979 in protocol witness for SyntaxProtocol.init(_:) in conformance SimpleTypeIdentifierSyntax ()
#4	0x00000001001acab7 in TypeSyntax.as<τ_0_0>(_:) at /Users/eric_horacek/Library/Developer/Xcode/DerivedData/Sourcery-hibchsafsxkdcjaxxaylrbeyoydh/SourcePackages/checkouts/swift-syntax/Sources/SwiftSyntax/gyb_generated/SyntaxBaseNodes.swift:421
```

I was able to reproduce this in the debugger, but there was no information available with either TSAN or ASAN.

Fixes #1009.

I know that a lot of folks rely on the performance of parsing in parallel and it only seems to be crashing on our codebase, so perhaps we could put this behind an argument?

* Add back OSAtomicIncrement32 for numberOfFilesThatHadToBeParsed

* Add a configuration flag for parsing in serial

* Add changelog entry

Author: erichoracek

CHANGELOG.md

@@ -1,6 +1,9 @@
 # Sourcery CHANGELOG
 
 ## 1.8.1
+## New Features
+- Added a new flag `--serialParse` to support parsing the sources in serial, rather than in parallel (the default), which can address stability issues in SwiftSyntax [#1063](https://github.com/krzysztofzablocki/Sourcery/pull/1063)
+
 ## Internal Changes
 - Lower project requirements to allow compilation using Swift 5.5/Xcode 13.x [#1049](https://github.com/krzysztofzablocki/Sourcery/pull/1049)
 - Update Stencil to 0.14.2

Sourcery/Sourcery.swift

@@ -30,6 +30,7 @@ public class Sourcery {
     fileprivate let cacheDisabled: Bool
     fileprivate let cacheBasePath: Path?
     fileprivate let prune: Bool
+    fileprivate let serialParse: Bool
 
     fileprivate var status = ""
     fileprivate var templatesPaths = Paths(include: [])
@@ -44,13 +45,14 @@ public class Sourcery {
     }
 
     /// Creates Sourcery processor
-    public init(verbose: Bool = false, watcherEnabled: Bool = false, cacheDisabled: Bool = false, cacheBasePath: Path? = nil, prune: Bool = false, arguments: [String: NSObject] = [:]) {
+    public init(verbose: Bool = false, watcherEnabled: Bool = false, cacheDisabled: Bool = false, cacheBasePath: Path? = nil, prune: Bool = false, serialParse: Bool = false, arguments: [String: NSObject] = [:]) {
         self.verbose = verbose
         self.arguments = arguments
         self.watcherEnabled = watcherEnabled
         self.cacheDisabled = cacheDisabled
         self.cacheBasePath = cacheBasePath
         self.prune = prune
+        self.serialParse = serialParse
     }
 
     /// Processes source files and generates corresponding code.
@@ -309,16 +311,24 @@ extension Sourcery {
             numberOfFilesThatHadToBeParsed = 0
 
             var lastError: Swift.Error?
-            let results = parserGenerator.parallelCompactMap { parser -> FileParserResult? in
+
+            let transform: (ParserWrapper) -> FileParserResult? = { parser in
                 do {
-                    return try self.loadOrParse(parser: parser, cachesPath: cachesDir(sourcePath: from))
+                    return try self.loadOrParse(parser: parser, cachesPath: self.cachesDir(sourcePath: from))
                 } catch {
                     lastError = error
                     Log.error("Unable to parse \(parser.path), error \(error)")
                     return nil
                 }
             }
 
+            let results: [FileParserResult]
+            if serialParse {
+                results = parserGenerator.compactMap(transform)
+            } else {
+                results = parserGenerator.parallelCompactMap(transform: transform)
+            }
+
             if let error = lastError {
                 throw error
             }

SourceryExecutable/main.swift

@@ -96,6 +96,7 @@ func runCLI() {
         Flag("parseDocumentation", description: "Include documentation comments for all declarations."),
         Flag("quiet", flag: "q", description: "Turn off any logging, only emmit errors."),
         Flag("prune", flag: "p", description: "Remove empty generated files"),
+        Flag("serialParse", description: "Parses the specified sources in serial, rather than in parallel (the default), which can address stability issues in SwiftSyntax."),
         VariadicOption<Path>("sources", description: "Path to a source swift files. File or Directory."),
         VariadicOption<Path>("exclude-sources", description: "Path to a source swift files to exclude. File or Directory."),
         VariadicOption<Path>("templates", description: "Path to templates. File or Directory."),
@@ -111,7 +112,7 @@ func runCLI() {
         	via `argument.<name>`. To pass in string you should use escaped quotes (\\").
         	"""),
         Option<Path>("ejsPath", default: "", description: "Path to EJS file for JavaScript templates.")
-    ) { watcherEnabled, disableCache, verboseLogging, logAST, logBenchmark, parseDocumentation, quiet, prune, sources, excludeSources, templates, excludeTemplates, output, configPaths, forceParse, args, ejsPath in
+    ) { watcherEnabled, disableCache, verboseLogging, logAST, logBenchmark, parseDocumentation, quiet, prune, serialParse, sources, excludeSources, templates, excludeTemplates, output, configPaths, forceParse, args, ejsPath in
         do {
             switch (quiet, verboseLogging) {
             case (true, _):
@@ -192,6 +193,7 @@ func runCLI() {
                                         cacheDisabled: disableCache,
                                         cacheBasePath: configuration.cacheBasePath,
                                         prune: prune,
+                                        serialParse: serialParse,
                                         arguments: configuration.args)
 
                 return try sourcery.processFiles(