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

[Owen Pan via cfe-commits]

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@@ -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);
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owenca wrote:

There's a little too much duplication now. Can you simplify/extract/combine this part?

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