[clang-format] Fix include sorting bug

[kentsommer]

Summary

• Fixes a bug that caused // clang-format off in a includes section to disabled include sorting even after a // clang-format on was found.

[curdeius]

Seems to be a duplicate of D94206.

[kentsommer]

In D94287#2486099, @curdeius wrote:

Seems to be a duplicate of D94206.

Right you are! Thanks for catching that! I'll abandon this one in favor of the one that has already been reviewed.

clang/lib/Format/Format.cpp

if (!FormattingOff && !Line.endswith("\\")) {
         IncludesInBlock.push_back(
             {IncludeName, Line, Prev, Category, Priority});
       } else if (!IncludesInBlock.empty() && !EmptyLineSkipped) {
         sortCppIncludes(Style, IncludesInBlock, Ranges, FileName, Code,
                         Replaces, Cursor);
         IncludesInBlock.clear();
         FirstIncludeBlock = false;
       }
-      Prev = Pos + 1;
     }
+    Prev = Pos + 1;
     if (Pos == StringRef::npos || Pos + 1 == Code.size())
       break;
     SearchFrom = Pos + 1;
   }
   if (!IncludesInBlock.empty()) {
     sortCppIncludes(Style, IncludesInBlock, Ranges, FileName, Code, Replaces,
                     Cursor);
   }

clang/test/Format/line-disable-include-sorting.cpp

+// RUN: grep -Ev "// *[A-Z-]+:" %s \
+// RUN:   | clang-format -style="{BasedOnStyle: LLVM, SortIncludes: true}" \
+// RUN:   | FileCheck -strict-whitespace %s
+// CHECK: {{^//\ clang-format\ off$}}
+// CHECK-NEXT: {{^#include\ <c>$}}
+// CHECK-NEXT: {{^//\ clang-format\ on$}}
+// CHECK-NEXT: {{^#include\ <a>$}}
+// CHECK-NEXT: {{^#include\ <b>$}}
+// clang-format off
+#include <c>
+// clang-format on
+#include <b>
+#include <a>