Fail with diagnostic on non-boolean macro arguments

realm · Oct 19, 2023 · b87467f · b87467f
1 parent 3ce2d60
commit b87467f
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Showing 3 changed files with 50 additions and 34 deletions.
diff --git a/Source/SwiftLintCoreMacros/SwiftLintCoreMacros.swift b/Source/SwiftLintCoreMacros/SwiftLintCoreMacros.swift
@@ -16,6 +16,7 @@ enum SwiftLintCoreMacroError: String, DiagnosticMessage {
     case notStruct = "Attribute can only be applied to structs"
     case notEnum = "Attribute can only be applied to enums"
     case noStringRawType = "Attribute can only be applied to enums with a 'String' raw type"
+    case noBooleanLiteral = "Macro argument must be a boolean literal"
 
     var message: String {
         rawValue

diff --git a/Source/SwiftLintCoreMacros/SwiftSyntaxRule.swift b/Source/SwiftLintCoreMacros/SwiftSyntaxRule.swift
@@ -1,4 +1,5 @@
 import SwiftSyntax
+import SwiftSyntaxBuilder
 import SwiftSyntaxMacros
 
 enum SwiftSyntaxRule: ExtensionMacro {
@@ -9,49 +10,52 @@ enum SwiftSyntaxRule: ExtensionMacro {
         conformingTo protocols: [TypeSyntax],
         in context: some MacroExpansionContext
     ) throws -> [ExtensionDeclSyntax] {
-        return [
+        [
             try ExtensionDeclSyntax("""
                 extension \(type): SwiftSyntaxRule {
                     func makeVisitor(file: SwiftLintFile) -> ViolationsSyntaxVisitor<ConfigurationType> {
                         Visitor(configuration: configuration, file: file)
                     }
                 }
-                """),
-            try createFoldingPreprocessor(type: type, foldArgument: node.foldArgument),
-            try createRewriter(type: type, rewriterArgument: node.explicitRewriterArgument)
+                """
+            ),
+            try makeExtension(dependingOn: node.foldArgument, in: context, with: """
+                extension \(type) {
+                    func preprocess(file: SwiftLintFile) -> SourceFileSyntax? {
+                        file.foldedSyntaxTree
+                    }
+                }
+                """
+            ),
+            try makeExtension(dependingOn: node.explicitRewriterArgument, in: context, with: """
+                extension \(type): SwiftSyntaxCorrectableRule {
+                    func makeRewriter(file: SwiftLintFile) -> (some ViolationsSyntaxRewriter)? {
+                        Rewriter(
+                            locationConverter: file.locationConverter,
+                            disabledRegions: disabledRegions(file: file)
+                        )
+                    }
+                }
+                """
+            )
         ].compactMap { $0 }
     }
 
-    private static func createFoldingPreprocessor(
-        type: some TypeSyntaxProtocol,
-        foldArgument: ExprSyntax?
+    private static func makeExtension(
+        dependingOn argument: ExprSyntax?,
+        in context: some MacroExpansionContext,
+        with content: SyntaxNodeString
     ) throws -> ExtensionDeclSyntax? {
-        guard foldArgument.isTrueLiteral else {
-            return nil
-        }
-        return try ExtensionDeclSyntax("""
-            extension \(type) {
-                func preprocess(file: SwiftLintFile) -> SourceFileSyntax? {
-                    file.foldedSyntaxTree
+        if let argument {
+            if argument.isBooleanLiteral {
+                if argument.isTrueLiteral {
+                    return try ExtensionDeclSyntax(content)
                 }
+            } else {
+                context.diagnose(SwiftLintCoreMacroError.noBooleanLiteral.diagnose(at: argument))
             }
-            """)
-    }
-
-    private static func createRewriter(
-        type: some TypeSyntaxProtocol,
-        rewriterArgument: ExprSyntax?
-    ) throws -> ExtensionDeclSyntax? {
-        guard rewriterArgument.isTrueLiteral else {
-            return nil
         }
-        return try ExtensionDeclSyntax("""
-            extension \(type): SwiftSyntaxCorrectableRule {
-                func makeRewriter(file: SwiftLintFile) -> (some ViolationsSyntaxRewriter)? {
-                    Rewriter(locationConverter: file.locationConverter, disabledRegions: disabledRegions(file: file))
-                }
-            }
-            """)
+        return nil
     }
 }
 
@@ -73,8 +77,12 @@ private extension AttributeSyntax {
     }
 }
 
-private extension ExprSyntax? {
+private extension ExprSyntax {
+    var isBooleanLiteral: Bool {
+        `is`(BooleanLiteralExprSyntax.self)
+    }
+
     var isTrueLiteral: Bool {
-        self?.as(BooleanLiteralExprSyntax.self)?.literal.text == "true"
+        `as`(BooleanLiteralExprSyntax.self)?.literal.text == "true"
     }
 }
diff --git a/Tests/MacroTests/SwiftSyntaxRuleTests.swift b/Tests/MacroTests/SwiftSyntaxRuleTests.swift
@@ -68,7 +68,10 @@ final class SwiftSyntaxRuleTests: XCTestCase {
 
             extension Hello: SwiftSyntaxCorrectableRule {
                 func makeRewriter(file: SwiftLintFile) -> (some ViolationsSyntaxRewriter)? {
-                    Rewriter(locationConverter: file.locationConverter, disabledRegions: disabledRegions(file: file))
+                    Rewriter(
+                        locationConverter: file.locationConverter,
+                        disabledRegions: disabledRegions(file: file)
+                    )
                 }
             }
             """,
@@ -77,7 +80,7 @@ final class SwiftSyntaxRuleTests: XCTestCase {
     }
 
     func testArbitraryArguments() {
-        // Silently fail because the macro definition explicitly requires a bool arguments.
+        // Fail with a diagnostic because the macro definition explicitly requires bool arguments.
         assertMacroExpansion(
             """
             @SwiftSyntaxRule(foldExpressions: variable, explicitRewriter: variable)
@@ -92,6 +95,10 @@ final class SwiftSyntaxRuleTests: XCTestCase {
                 }
             }
             """,
+            diagnostics: [
+                DiagnosticSpec(message: SwiftLintCoreMacroError.noBooleanLiteral.message, line: 1, column: 35),
+                DiagnosticSpec(message: SwiftLintCoreMacroError.noBooleanLiteral.message, line: 1, column: 63)
+            ],
             macros: macros
         )
     }