improve generics tests; prevent out of bounds access

formatting

Author: ktoso

Sources/SwiftSyntaxMacroExpansion/MacroReplacement.swift

@@ -331,6 +331,10 @@ private final class MacroExpansionRewriter: SyntaxRewriter {
       return super.visit(node)
     }
 
+    guard parameterIndex < genericArguments.count else {
+      return super.visit(node)
+    }
+
     // Swap in the argument for type parameter
     return GenericArgumentSyntax(
       leadingTrivia: node.leadingTrivia,
@@ -339,9 +343,9 @@ private final class MacroExpansionRewriter: SyntaxRewriter {
       node.unexpectedBetweenArgumentAndTrailingComma,
       trailingComma: node.trailingComma,
       node.unexpectedAfterTrailingComma
-      // TODO: seems we're getting spurious trailing " " here,
-      //  skipping trailing trivia for now
-      // trailingTrivia: node.trailingTrivia
+        // TODO: seems we're getting spurious trailing " " here,
+        //  skipping trailing trivia for now
+        // trailingTrivia: node.trailingTrivia
     )
   }
 }
@@ -359,27 +363,25 @@ extension MacroDeclSyntax {
     // FIXME: Do real call-argument matching between the argument list and the
     // macro parameter list, porting over from the compiler.
     let parameterReplacements = Dictionary(
-        uniqueKeysWithValues: replacements.map { replacement in
-          (replacement.reference, replacement.parameterIndex)
-        }
-      )
+      uniqueKeysWithValues: replacements.map { replacement in
+        (replacement.reference, replacement.parameterIndex)
+      }
+    )
     let arguments: [ExprSyntax] =
       argumentList?.map { element in
         element.expression
       } ?? []
 
-
     let genericReplacements = Dictionary(
       uniqueKeysWithValues: genericReplacements.map { replacement in
         (replacement.reference, replacement.parameterIndex)
       }
     )
     let genericArguments: [TypeSyntax] =
-      genericArgumentList?.arguments.map { element in 
+      genericArgumentList?.arguments.map { element in
         element.argument
       } ?? []
 
-
     let rewriter: MacroExpansionRewriter = MacroExpansionRewriter(
       parameterReplacements: parameterReplacements,
       arguments: arguments,

Tests/SwiftSyntaxMacroExpansionTest/MacroReplacementTests.swift

@@ -132,7 +132,7 @@ final class MacroReplacementTests: XCTestCase {
       XCTFail("not a normal expansion")
       return
     }
-    
+
     let replacementA = try XCTUnwrap(genericReplacements.first)
     let replacementB = try XCTUnwrap(genericReplacements.dropFirst().first)
 
@@ -237,12 +237,12 @@ final class MacroReplacementTests: XCTestCase {
   func testMacroGenericArgumentExpansion_replaceInner() throws {
     let macro: DeclSyntax =
       """
-      macro gen<A>(a: Array<A>) = #otherMacro(first: a)
+      macro gen<A>(a: Array<A>) = #reduce<A>(first: a)
       """
 
     let use: ExprSyntax =
       """
-      #gen(a: [1, 2, 3])
+      #gen<Int>(a: [1, 2, 3])
       """
 
     let macroDecl = macro.as(MacroDeclSyntax.self)!
@@ -252,7 +252,7 @@ final class MacroReplacementTests: XCTestCase {
       return
     }
 
-    XCTAssertEqual(genericReplacements.count, 0)
+    XCTAssertEqual(genericReplacements.count, 1)
 
     let expandedSyntax = macroDecl.expand(
       use.as(MacroExpansionExprSyntax.self)!,
@@ -263,7 +263,7 @@ final class MacroReplacementTests: XCTestCase {
     assertStringsEqualWithDiff(
       expandedSyntax.description,
       """
-      #otherMacro(first: [1, 2, 3])
+      #reduce<Int>(first: [1, 2, 3])
       """
     )
   }