Implement a CountedStorageMap (#9125)

* initial impl

* expose in pallet_prelude

* temp test

* Apply suggestions from code review

Co-authored-by: Peter Goodspeed-Niklaus <coriolinus@users.noreply.github.com>
Co-authored-by: Xiliang Chen <xlchen1291@gmail.com>

* implement with macro help.

* test for macro generation

* add iterable functions, some test and fixes

* fix merge

* doc

* Update frame/support/src/storage/types/counted_map.rs

Co-authored-by: Zeke Mostov <32168567+emostov@users.noreply.github.com>

* fix merge

* fmt

* fix spelling

* improve on removal

* fix partial storage info

* fmt

* add license

* suggested renames

* fix typo

* fix test

* fmt

* fix ui tests

* clearer doc

* better doc

* add metadata test

Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>
Co-authored-by: Peter Goodspeed-Niklaus <coriolinus@users.noreply.github.com>
Co-authored-by: Xiliang Chen <xlchen1291@gmail.com>
Co-authored-by: Zeke Mostov <32168567+emostov@users.noreply.github.com>

substrate/frame/support/src/storage/generator/double_map.rs

@@ -219,6 +219,7 @@ where
 			previous_key: prefix,
 			drain: false,
 			closure: |_raw_key, mut raw_value| V::decode(&mut raw_value),
+			phantom: Default::default(),
 		}
 	}
 
@@ -345,6 +346,7 @@ where
 				let mut key_material = G::Hasher2::reverse(raw_key_without_prefix);
 				Ok((K2::decode(&mut key_material)?, V::decode(&mut raw_value)?))
 			},
+			phantom: Default::default(),
 		}
 	}
 
@@ -398,6 +400,7 @@ where
 				let k2 = K2::decode(&mut k2_material)?;
 				Ok((k1, k2, V::decode(&mut raw_value)?))
 			},
+			phantom: Default::default(),
 		}
 	}
 

substrate/frame/support/src/storage/generator/map.rs

@@ -138,6 +138,7 @@ where
 				let mut key_material = G::Hasher::reverse(raw_key_without_prefix);
 				Ok((K::decode(&mut key_material)?, V::decode(&mut raw_value)?))
 			},
+			phantom: Default::default(),
 		}
 	}
 

substrate/frame/support/src/storage/generator/nmap.rs

@@ -196,6 +196,7 @@ where
 			previous_key: prefix,
 			drain: false,
 			closure: |_raw_key, mut raw_value| V::decode(&mut raw_value),
+			phantom: Default::default(),
 		}
 	}
 
@@ -305,6 +306,7 @@ impl<K: ReversibleKeyGenerator, V: FullCodec, G: StorageNMap<K, V>>
 				let partial_key = K::decode_partial_key(raw_key_without_prefix)?;
 				Ok((partial_key, V::decode(&mut raw_value)?))
 			},
+			phantom: Default::default(),
 		}
 	}
 
@@ -368,6 +370,7 @@ impl<K: ReversibleKeyGenerator, V: FullCodec, G: StorageNMap<K, V>>
 				let (final_key, _) = K::decode_final_key(raw_key_without_prefix)?;
 				Ok((final_key, V::decode(&mut raw_value)?))
 			},
+			phantom: Default::default(),
 		}
 	}