[AutoDiff upstream] NFC: update IndexSubset print/dump utilities. (#27775)

Cherry-pick #27772 from tensorflow branch.

Author: dan-zheng

include/swift/AST/IndexSubset.h

@@ -201,19 +201,10 @@ class IndexSubset : public llvm::FoldingSetNode {
       id.AddInteger(index);
   }
 
-  void print(llvm::raw_ostream &s = llvm::outs()) const {
-    s << '{';
-    interleave(range(capacity), [this, &s](unsigned i) { s << contains(i); },
-               [&s] { s << ", "; });
-    s << '}';
-  }
-
-  void dump(llvm::raw_ostream &s = llvm::errs()) const {
-    s << "(index_subset capacity=" << capacity << " indices=(";
-    interleave(getIndices(), [&s](unsigned i) { s << i; },
-               [&s] { s << ", "; });
-    s << "))";
-  }
+  void print(llvm::raw_ostream &s = llvm::outs()) const;
+  LLVM_ATTRIBUTE_DEPRECATED(void dump(llvm::raw_ostream &s = llvm::errs())
+                                const LLVM_ATTRIBUTE_USED,
+                            "only for use within the debugger");
 
   int findNext(int startIndex) const;
   int findFirst() const { return findNext(-1); }

lib/AST/IndexSubset.cpp

@@ -79,6 +79,20 @@ IndexSubset *IndexSubset::extendingCapacity(
   return IndexSubset::get(ctx, indices);
 }
 
+void IndexSubset::print(llvm::raw_ostream &s) const {
+  s << '{';
+  interleave(range(capacity), [this, &s](unsigned i) { s << contains(i); },
+             [&s] { s << ", "; });
+  s << '}';
+}
+
+void IndexSubset::dump(llvm::raw_ostream &s) const {
+  s << "(index_subset capacity=" << capacity << " indices=(";
+  interleave(getIndices(), [&s](unsigned i) { s << i; },
+             [&s] { s << ", "; });
+  s << "))\n";
+}
+
 int IndexSubset::findNext(int startIndex) const {
   assert(startIndex < (int)capacity && "Start index cannot be past the end");
   unsigned bitWordIndex = 0, offset = 0;