[lld] [LLD] Add CLASS syntax to SECTIONS (PR #95323)

[Fangrui Song via llvm-commits]

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@@ -717,14 +752,66 @@ void LinkerScript::processSectionCommands() {
       } else if (process(osec)) {
         osec->sectionIndex = i++;
       }
+    } else if (auto *sc = dyn_cast<SectionClassDesc>(base)) {
+      for (InputSectionDescription *isd : sc->sc.commands) {
+        isd->sectionBases =
+            computeInputSections(isd, ctx.inputSections, sc->sc);
+        for (InputSectionBase *s : isd->sectionBases) {
+          // Section classes with --enable-non-contiguous-regions may contain
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MaskRay wrote:

This comment is not accurate. This code path is useful even if --enable-non-contiguous-regions is unused.

https://github.com/llvm/llvm-project/pull/95323