[clang] clang-format: Add IncludeSortKey option (PR #137840)

[Owen Pan via cfe-commits]

================
@@ -3221,15 +3223,33 @@ static void sortCppIncludes(const FormatStyle &Style,
     stable_sort(Indices, [&](unsigned LHSI, unsigned RHSI) {
       const auto LHSFilenameLower = Includes[LHSI].Filename.lower();
       const auto RHSFilenameLower = Includes[RHSI].Filename.lower();
-      return std::tie(Includes[LHSI].Priority, LHSFilenameLower,
-                      Includes[LHSI].Filename) <
-             std::tie(Includes[RHSI].Priority, RHSFilenameLower,
-                      Includes[RHSI].Filename);
+      SmallString<128> LHSStem = Includes[LHSI].Filename;
+      SmallString<128> RHSStem = Includes[RHSI].Filename;
+      if (Style.IncludeStyle.IncludeSortKey ==
+          tooling::IncludeStyle::ISK_Stem) {
+        llvm::sys::path::replace_extension(LHSStem, "");
+        llvm::sys::path::replace_extension(RHSStem, "");
+      }
+      const auto LHSStemLower = LHSStem.str().lower();
+      const auto RHSStemLower = RHSStem.str().lower();
+      return std::tie(Includes[LHSI].Priority, LHSStemLower, LHSStem,
+                      LHSFilenameLower, Includes[LHSI].Filename) <
+             std::tie(Includes[RHSI].Priority, RHSStemLower, RHSStem,
+                      RHSFilenameLower, Includes[RHSI].Filename);
     });
   } else {
     stable_sort(Indices, [&](unsigned LHSI, unsigned RHSI) {
-      return std::tie(Includes[LHSI].Priority, Includes[LHSI].Filename) <
-             std::tie(Includes[RHSI].Priority, Includes[RHSI].Filename);
+      SmallString<128> LHSStem = Includes[LHSI].Filename;
+      SmallString<128> RHSStem = Includes[RHSI].Filename;
+      if (Style.IncludeStyle.IncludeSortKey ==
+          tooling::IncludeStyle::ISK_Stem) {
+        llvm::sys::path::replace_extension(LHSStem, "");
+        llvm::sys::path::replace_extension(RHSStem, "");
+      }
+      return std::tie(Includes[LHSI].Priority, LHSStem,
+                      Includes[LHSI].Filename) <
+             std::tie(Includes[RHSI].Priority, RHSStem,
+                      Includes[RHSI].Filename);
----------------
owenca wrote:

Something like the following:
```c++
@@ -3219,39 +3219,27 @@ static void sortCppIncludes(const FormatStyle &Style,
   SmallVector<unsigned, 16> Indices =
       llvm::to_vector<16>(llvm::seq<unsigned>(0, Includes.size()));
 
-  if (Style.SortIncludes == FormatStyle::SI_CaseInsensitive) {
-    stable_sort(Indices, [&](unsigned LHSI, unsigned RHSI) {
-      const auto LHSFilenameLower = Includes[LHSI].Filename.lower();
-      const auto RHSFilenameLower = Includes[RHSI].Filename.lower();
-      SmallString<128> LHSStem = Includes[LHSI].Filename;
-      SmallString<128> RHSStem = Includes[RHSI].Filename;
-      if (Style.IncludeStyle.IncludeSortKey ==
-          tooling::IncludeStyle::ISK_Stem) {
-        llvm::sys::path::replace_extension(LHSStem, "");
-        llvm::sys::path::replace_extension(RHSStem, "");
-      }
-      const auto LHSStemLower = LHSStem.str().lower();
-      const auto RHSStemLower = RHSStem.str().lower();
-      return std::tie(Includes[LHSI].Priority, LHSStemLower, LHSStem,
-                      LHSFilenameLower, Includes[LHSI].Filename) <
-             std::tie(Includes[RHSI].Priority, RHSStemLower, RHSStem,
-                      RHSFilenameLower, Includes[RHSI].Filename);
-    });
-  } else {
-    stable_sort(Indices, [&](unsigned LHSI, unsigned RHSI) {
-      SmallString<128> LHSStem = Includes[LHSI].Filename;
-      SmallString<128> RHSStem = Includes[RHSI].Filename;
-      if (Style.IncludeStyle.IncludeSortKey ==
-          tooling::IncludeStyle::ISK_Stem) {
-        llvm::sys::path::replace_extension(LHSStem, "");
-        llvm::sys::path::replace_extension(RHSStem, "");
-      }
-      return std::tie(Includes[LHSI].Priority, LHSStem,
-                      Includes[LHSI].Filename) <
-             std::tie(Includes[RHSI].Priority, RHSStem,
-                      Includes[RHSI].Filename);
-    });
-  }
+  stable_sort(Indices, [&](unsigned LHSI, unsigned RHSI) {
+    SmallString<128> LHSStem, RHSStem;
+    if (Style.IncludeStyle.IncludeSortKey == tooling::IncludeStyle::ISK_Stem) {
+      LHSStem = Includes[LHSI].Filename;
+      RHSStem = Includes[RHSI].Filename;
+      llvm::sys::path::replace_extension(LHSStem, "");
+      llvm::sys::path::replace_extension(RHSStem, "");
+    }
+    std::string LHSStemLower, RHSStemLower;
+    std::string LHSFilenameLower, RHSFilenameLower;
+    if (Style.SortIncludes == FormatStyle::SI_CaseInsensitive) {
+      LHSStemLower = LHSStem.str().lower();
+      RHSStemLower = RHSStem.str().lower();
+      LHSFilenameLower = Includes[LHSI].Filename.lower();
+      RHSFilenameLower = Includes[RHSI].Filename.lower();
+    }
+    return std::tie(Includes[LHSI].Priority, LHSStemLower, LHSStem,
+                    LHSFilenameLower, Includes[LHSI].Filename) <
+           std::tie(Includes[RHSI].Priority, RHSStemLower, RHSStem,
+                    RHSFilenameLower, Includes[RHSI].Filename);
+  });
 
   // The index of the include on which the cursor will be put after
   // sorting/deduplicating.
```

https://github.com/llvm/llvm-project/pull/137840