[clang-format] Hanlde qualified type name for QualifierAlignment (#125327)

Fixes #125178.

(cherry picked from commit eb6ca12)

Author: owenca

clang/lib/Format/QualifierAlignmentFixer.cpp

@@ -132,8 +132,10 @@ static void rotateTokens(const SourceManager &SourceMgr,
   // Then move through the other tokens.
   auto *Tok = Begin;
   while (Tok != End) {
-    if (!NewText.empty() && !endsWithSpace(NewText))
+    if (!NewText.empty() && !endsWithSpace(NewText) &&
+        Tok->isNot(tok::coloncolon)) {
       NewText += " ";
+    }
 
     NewText += Tok->TokenText;
     Tok = Tok->Next;
@@ -412,6 +414,14 @@ const FormatToken *LeftRightQualifierAlignmentFixer::analyzeLeft(
   // The case `const long long volatile int` -> `const volatile long long int`
   // The case `long volatile long int const` -> `const volatile long long int`
   if (TypeToken->isTypeName(LangOpts)) {
+    for (const auto *Prev = TypeToken->Previous;
+         Prev && Prev->is(tok::coloncolon); Prev = Prev->Previous) {
+      TypeToken = Prev;
+      Prev = Prev->Previous;
+      if (!(Prev && Prev->is(tok::identifier)))
+        break;
+      TypeToken = Prev;
+    }
     const FormatToken *LastSimpleTypeSpecifier = TypeToken;
     while (isConfiguredQualifierOrType(
         LastSimpleTypeSpecifier->getPreviousNonComment(),

clang/unittests/Format/QualifierFixerTest.cpp

@@ -1291,6 +1291,21 @@ TEST_F(QualifierFixerTest, WithCpp11Attribute) {
                "[[maybe_unused]] constexpr static int A", Style);
 }
 
+TEST_F(QualifierFixerTest, WithQualifiedTypeName) {
+  auto Style = getLLVMStyle();
+  Style.QualifierAlignment = FormatStyle::QAS_Custom;
+  Style.QualifierOrder = {"constexpr", "type", "const"};
+
+  verifyFormat("constexpr ::int64_t x{1};", "::int64_t constexpr x{1};", Style);
+  verifyFormat("constexpr std::int64_t x{123};",
+               "std::int64_t constexpr x{123};", Style);
+  verifyFormat("constexpr ::std::int64_t x{123};",
+               "::std::int64_t constexpr x{123};", Style);
+
+  Style.TypeNames.push_back("bar");
+  verifyFormat("constexpr foo::bar x{12};", "foo::bar constexpr x{12};", Style);
+}
+
 TEST_F(QualifierFixerTest, DisableRegions) {
   FormatStyle Style = getLLVMStyle();
   Style.QualifierAlignment = FormatStyle::QAS_Custom;