Disable a few assertions with non-trivial cost in release builds

This reduces the cost of enabling assertions in release builds to ~2%.

Author: ahoppen

CodeGeneration/Sources/generate-swiftsyntax/templates/swiftsyntax/RawSyntaxNodesFile.swift

@@ -135,11 +135,19 @@ let rawSyntaxNodesFile = SourceFileSyntax(leadingTrivia: "\(generateCopyrightHea
         """
       )
 
+      DeclSyntax(
+        """
+        init(unchecked raw: RawSyntax) {
+          self.raw = raw
+        }
+        """
+      )
+
       DeclSyntax(
         """
         public init?<Node: RawSyntaxNodeProtocol>(_ other: Node) {
           guard Self.isKindOf(other.raw) else { return nil }
-          self.init(raw: other.raw)
+          self.init(unchecked: other.raw)
         }
         """
       )
@@ -167,7 +175,7 @@ let rawSyntaxNodesFile = SourceFileSyntax(leadingTrivia: "\(generateCopyrightHea
                     ptr += 1
                   }
             }
-            self.init(raw: raw)
+            self.init(unchecked: raw)
           }
           """
         )

Sources/SwiftSyntax/Assert.swift

@@ -22,6 +22,14 @@ public func syntaxAssert(_ condition: @autoclosure () -> Bool, _ message: @autoc
   }
 }
 
+/// An assertion that is only active in DEBUG builds, just like Swift.assert.
+/// Use this instead of `syntaxAssert` in places where the assertion has a
+/// non-trivial cost but provides little value in release builds.
+@_transparent
+public func debugAssert(_ condition: @autoclosure () -> Bool, _ message: @autoclosure () -> String = String(), file: StaticString = #file, line: UInt = #line) {
+  Swift.assert(condition(), message(), file: file, line: line)
+}
+
 @available(*, deprecated, message: "Use syntaxAssertionFailure instead, which will also trap in release builds")
 public func assertionFailure(_ message: @autoclosure () -> String = String(), file: StaticString = #file, line: UInt = #line) {
   Swift.assertionFailure(message(), file: file, line: line)

Sources/SwiftSyntax/Raw/RawSyntax.swift

@@ -536,11 +536,11 @@ extension RawSyntax {
     tokenDiagnostic: TokenDiagnostic?,
     arena: __shared SyntaxArena
   ) -> RawSyntax {
-    syntaxAssert(
+    debugAssert(
       arena.contains(text: wholeText),
       "token text must be managed by the arena"
     )
-    syntaxAssert(
+    debugAssert(
       arena is ParsingSyntaxArena || textRange == wholeText.indices,
       "arena must be able to parse trivia"
     )