[libcxx-commits] [clang] [libcxx] [Clang] Normalize constraints before checking for satisfaction (PR #141776)

[Erich Keane via libcxx-commits]

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@@ -51,6 +51,27 @@ class FixedPointSemantics;
 struct fltSemantics;
 template <typename T, unsigned N> class SmallPtrSet;
 
+template <> struct DenseMapInfo<llvm::FoldingSetNodeID> {
+  static FoldingSetNodeID getEmptyKey() { return FoldingSetNodeID{}; }
+
+  static FoldingSetNodeID getTombstoneKey() {
+    FoldingSetNodeID id;
+    for (size_t i = 0; i < sizeof(id) / sizeof(unsigned); ++i) {
+      id.AddInteger(std::numeric_limits<unsigned>::max());
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erichkeane wrote:

Ooof... this is a little opaque.  Perhaps instead `FoldingSetNodeID` should have a 'set-all-ones' bit here. While this CURRENTLY works, I fear the effect this coy-implementation will have on any changes to that.  Also, using the `sizeof` the `id` to try to figure out the `SmallVector` optimization size feels wrong too.  

https://github.com/llvm/llvm-project/pull/141776