[llvm] ADT: Improve DenseMap documentation for insertion APIs (PR #172177)

[Jakub Kuderski via llvm-commits]

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@@ -208,9 +208,9 @@ class DenseMapBase : public DebugEpochBase {
     return ValueT();
   }
 
-  // Return the entry with the specified key, or \p Default. This variant is
-  // useful, because `lookup` cannot be used with non-default-constructible
-  // values.
+  /// Returns the mapped value for Val if present, otherwise Default.
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kuhar wrote:

I still think it'd be better to change the argument name from Val to Key

https://github.com/llvm/llvm-project/pull/172177