[clang-format] Don't alter SpacesRequiredBefore of finalized tokens (#69897)

Fixes #69237.

Author: owenca

clang/lib/Format/TokenAnnotator.cpp

@@ -3544,7 +3544,7 @@ void TokenAnnotator::calculateFormattingInformation(AnnotatedLine &Line) const {
           }
         }
       }
-    } else if (Current->SpacesRequiredBefore == 0 &&
+    } else if (!Current->Finalized && Current->SpacesRequiredBefore == 0 &&
                spaceRequiredBefore(Line, *Current)) {
       Current->SpacesRequiredBefore = 1;
     }

clang/unittests/Format/FormatTest.cpp

@@ -26459,6 +26459,25 @@ TEST_F(FormatTest, AllowBreakBeforeNoexceptSpecifier) {
                Style);
 }
 
+TEST_F(FormatTest, PPBranchesInBracedInit) {
+  verifyFormat("A a_{kFlag1,\n"
+               "#if BUILD_FLAG\n"
+               "     kFlag2,\n"
+               "#else\n"
+               "     kFlag3,\n"
+               "#endif\n"
+               "     kFlag4};",
+               "A a_{\n"
+               "  kFlag1,\n"
+               "#if BUILD_FLAG\n"
+               "      kFlag2,\n"
+               "#else\n"
+               "      kFlag3,\n"
+               "#endif\n"
+               "      kFlag4\n"
+               "};");
+}
+
 } // namespace
 } // namespace test
 } // namespace format