From e0524731fa4e66ecbd74c5fb4f7ff4e0112c3d79 Mon Sep 17 00:00:00 2001
From: Copilot <198982749+Copilot@users.noreply.github.com>
Date: Sat, 21 Feb 2026 09:52:19 -0800
Subject: [PATCH] Update `parseType` to support Swift 6.4 `::` module selector
 syntax (#2399)

Co-authored-by: calda <1811727+calda@users.noreply.github.com>
---
 Sources/ParsingHelpers.swift    | 11 +++++++++++
 Tests/ParsingHelpersTests.swift | 30 ++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+)

diff --git a/Sources/ParsingHelpers.swift b/Sources/ParsingHelpers.swift
index 448e39c4..8869c5ad 100644
--- a/Sources/ParsingHelpers.swift
+++ b/Sources/ParsingHelpers.swift
@@ -1490,6 +1490,17 @@ extension Formatter {
             return TypeName(range: startOfTypeIndex ... followingType.range.upperBound, formatter: self)
         }
 
+        // `::` can also continue a type (e.g. `Module::Type`), but unlike `.` and `&`,
+        // there must be no newline between `::` and the following identifier.
+        if let nextTokenIndex = index(of: .nonSpaceOrCommentOrLinebreak, after: baseType.range.upperBound),
+           tokens[nextTokenIndex] == .operator("::", .infix),
+           let afterDoubleColonIndex = index(of: .nonSpaceOrComment, after: nextTokenIndex),
+           !tokens[afterDoubleColonIndex].isLinebreak,
+           let followingType = parseType(at: afterDoubleColonIndex, excludeLowercaseIdentifiers: excludeLowercaseIdentifiers)
+        {
+            return TypeName(range: startOfTypeIndex ... followingType.range.upperBound, formatter: self)
+        }
+
         return baseType
     }
 
diff --git a/Tests/ParsingHelpersTests.swift b/Tests/ParsingHelpersTests.swift
index 5196841a..d4fd687b 100644
--- a/Tests/ParsingHelpersTests.swift
+++ b/Tests/ParsingHelpersTests.swift
@@ -2397,6 +2397,36 @@ final class ParsingHelpersTests: XCTestCase {
         XCTAssertEqual(formatter.parseType(at: 2)?.string, "Foo.Bar.Baaz.Quux.InnerType1.InnerType2")
     }
 
+    func testParseModuleQualifiedType() {
+        let formatter = Formatter(tokenize("""
+        let foo: Module::Type
+        """))
+        XCTAssertEqual(formatter.parseType(at: 5)?.string, "Module::Type")
+    }
+
+    func testParseNestedModuleQualifiedType() {
+        let formatter = Formatter(tokenize("""
+        let foo: Module::Type.Module::Subtype
+        """))
+        XCTAssertEqual(formatter.parseType(at: 5)?.string, "Module::Type.Module::Subtype")
+    }
+
+    func testParseModuleQualifiedTypeWithNewlineBeforeDoubleColon() {
+        let formatter = Formatter(tokenize("""
+        let foo: NationalAeronauticsAndSpaceAdministration
+            ::RocketEngine
+        """))
+        XCTAssertEqual(formatter.parseType(at: 5)?.string, "NationalAeronauticsAndSpaceAdministration::RocketEngine")
+    }
+
+    func testDoesntParseModuleQualifiedTypeWithNewlineAfterDoubleColon() {
+        let formatter = Formatter(tokenize("""
+        let foo: NationalAeronauticsAndSpaceAdministration::
+            RocketEngine
+        """))
+        XCTAssertEqual(formatter.parseType(at: 5)?.string, "NationalAeronauticsAndSpaceAdministration")
+    }
+
     func testParseTuples() {
         let input = """
         let tuple: (foo: Foo, bar: Bar)