Introduce warning to rename targetEnvironment(macabi) to macCatalyst

This matches the behavior of the compiler.

Author: DougGregor

Sources/SwiftIfConfig/IfConfigError.swift

@@ -32,6 +32,7 @@ enum IfConfigError: Error, CustomStringConvertible {
   case integerLiteralCondition(syntax: ExprSyntax, replacement: Bool)
   case likelySimulatorPlatform(syntax: ExprSyntax)
   case endiannessDoesNotMatch(syntax: ExprSyntax, argument: String)
+  case macabiIsMacCatalyst(syntax: ExprSyntax)
 
   var description: String {
     switch self {
@@ -83,6 +84,9 @@ enum IfConfigError: Error, CustomStringConvertible {
       return
         "platform condition appears to be testing for simulator environment; use 'targetEnvironment(simulator)' instead"
 
+    case .macabiIsMacCatalyst:
+      return "'macabi' has been renamed to 'macCatalyst'"
+
     case .endiannessDoesNotMatch:
       return "unknown endianness for build configuration '_endian' (must be 'big' or 'little')"
     }
@@ -105,7 +109,8 @@ enum IfConfigError: Error, CustomStringConvertible {
       .ignoredTrailingComponents(version: _, syntax: let syntax),
       .integerLiteralCondition(syntax: let syntax, replacement: _),
       .likelySimulatorPlatform(syntax: let syntax),
-      .endiannessDoesNotMatch(syntax: let syntax, argument: _):
+      .endiannessDoesNotMatch(syntax: let syntax, argument: _),
+      .macabiIsMacCatalyst(syntax: let syntax):
       return Syntax(syntax)
 
     case .unsupportedVersionOperator(name: _, operator: let op):
@@ -124,7 +129,7 @@ extension IfConfigError: DiagnosticMessage {
   var severity: SwiftDiagnostics.DiagnosticSeverity {
     switch self {
     case .compilerVersionSecondComponentNotWildcard, .ignoredTrailingComponents,
-      .likelySimulatorPlatform, .endiannessDoesNotMatch:
+      .likelySimulatorPlatform, .endiannessDoesNotMatch, .macabiIsMacCatalyst:
       return .warning
     default: return .error
     }
@@ -171,6 +176,21 @@ extension IfConfigError: DiagnosticMessage {
       )
     }
 
+    // For the targetEnvironment(macabi) -> macCatalyst rename we have a Fix-It.
+    if case .macabiIsMacCatalyst(syntax: let syntax) = self {
+      return Diagnostic(
+        node: syntax,
+        message: self,
+        fixIt: .replace(
+          message: SimpleFixItMessage(
+            message: "replace with 'macCatalyst'"
+          ),
+          oldNode: syntax,
+          newNode: "macCatalyst" as ExprSyntax
+        )
+      )
+    }
+
     return Diagnostic(node: syntax, message: self)
   }
 }

Sources/SwiftIfConfig/IfConfigEvaluation.swift

@@ -203,13 +203,23 @@ func evaluateIfConfig(
     ) -> (active: Bool, syntaxErrorsAllowed: Bool, diagnostics: [Diagnostic]) {
       // Ensure that we have a single argument that is a simple identifier.
       guard let argExpr = call.arguments.singleUnlabeledExpression,
-        let arg = argExpr.simpleIdentifierExpr
+        var arg = argExpr.simpleIdentifierExpr
       else {
         return recordError(
           .requiresUnlabeledArgument(name: fnName, role: role, syntax: ExprSyntax(call))
         )
       }
 
+      // The historical "macabi" environment has been renamed to "macCatalyst".
+      if role == "environment" && arg == "macabi" {
+        extraDiagnostics.append(
+          IfConfigError.macabiIsMacCatalyst(syntax: argExpr)
+            .asDiagnostic
+        )
+
+        arg = "macCatalyst"
+      }
+
       return checkConfiguration(at: argExpr) {
         (active: try body(arg), syntaxErrorsAllowed: fn.syntaxErrorsAllowed)
       }
@@ -304,8 +314,8 @@ func evaluateIfConfig(
       } else {
         // Complain about unknown endianness
         extraDiagnostics.append(
-          contentsOf: IfConfigError.endiannessDoesNotMatch(syntax: argExpr, argument: arg)
-            .asDiagnostics(at: argExpr)
+          IfConfigError.endiannessDoesNotMatch(syntax: argExpr, argument: arg)
+            .asDiagnostic
         )
 
         isActive = false

Tests/SwiftIfConfigTest/EvaluateTests.swift

@@ -183,6 +183,22 @@ public class EvaluateTests: XCTestCase {
         )
       ]
     )
+
+    assertIfConfig(
+      "targetEnvironment(macabi)",
+      .inactive,
+      diagnostics: [
+        DiagnosticSpec(
+          message: "'macabi' has been renamed to 'macCatalyst'",
+          line: 1,
+          column: 19,
+          severity: .warning,
+          fixIts: [
+            FixItSpec(message: "replace with 'macCatalyst'")
+          ]
+        )
+      ]
+    )
   }
 
   func testVersions() throws {