feat(docs): add documentation for basechain address related struct and functions (#2411)

- `BasechainAddress`
- `emptyBasechainAddress`
- `newBasechainAddress`
- `contractBasechainAddress`
- `storeBasechainAddress`
- add entry to CHANGELOG.md for 1.6.0

Author: i582

dev-docs/CHANGELOG.md

@@ -20,12 +20,14 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Removed the "gas-expensive" badge from `checkSignature()` and `checkDataSignature()` functions and added a caution note when they do become expensive (from 11th call): PR [#2380](https://github.com/tact-lang/tact/pull/2380)
 - Fixed descriptions of `Slice.asString()` and `String.asSlice()` functions: PR [#2391](https://github.com/tact-lang/tact/pull/2391)
 - Split Core libraries in the reference: `core-common` and `core-advanced` were removed, and their contents distributed across other libraries; `core-crypto`, `core-contextstate`, `core-send`, `core-gas`, and `core-addresses` were introduced: PR [#2391](https://github.com/tact-lang/tact/pull/2391)
+- Added documentation for `BasechainAddress`, `emptyBasechainAddress`, `newBasechainAddress`, `contractBasechainAddress`, `Builder.storeBasechainAddress`: PR [#2411](https://github.com/tact-lang/tact/pull/2411)
 
 ### Release contributors
 
 - [Novus Nota](https://github.com/novusnota)
 - [Anton Trunov](https://github.com/anton-trunov)
 - [Maksim Lagus](https://github.com/Kaladin13)
+- [Petr Makhnev](https://github.com/i582)
 
 ## [1.6.3] - 2025-03-12
 
@@ -183,7 +185,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Added new functions in stdlib: `Builder.depth`, `Slice.skipLastBits`, `Slice.firstBits`, `Slice.lastBits`, `Slice.depth`, `Cell.computeDataSize`, `Slice.computeDataSize`, `Cell.depth`, `curLt`, `blockLt`, `setGasLimit`, `getSeed`, `setSeed`, `myCode`, `sign`, `divc`, `muldivc`, `mulShiftRight`, `mulShiftRightRound`, `mulShiftRightCeil`, `sqrt`, `Slice.loadMaybeRef`, `Slice.preloadMaybeRef`: PR [#986](https://github.com/tact-lang/tact/pull/986), PR [#2040](https://github.com/tact-lang/tact/pull/2040)
 - Added new functions `Slice.asAddress`, `Slice.asAddressUnsafe` and `contractHash`: PR [#1766](https://github.com/tact-lang/tact/pull/1766)
 - Added new functions `throwIf` and `throwUnless` and deprecated their aliases `nativeThrowIf` and `nativeThrowUnless`: PR [#1974](https://github.com/tact-lang/tact/pull/1974)
-- Added the `BasechainAddress` type as a more optimized version of the `Address` type: PR [#2035](https://github.com/tact-lang/tact/pull/2035)
+- Added the `BasechainAddress` type as a more optimized version of the `Address` type. And also the `emptyBasechainAddress`, `newBasechainAddress`, `contractBasechainAddress`, `Builder.storeBasechainAddress` functions: PR [#2035](https://github.com/tact-lang/tact/pull/2035)
 - Added the `Slice.hashData()` and `String.hashData()` functions: PR [#2039](https://github.com/tact-lang/tact/pull/2039)
 - Optimized the `emptyCell()` and `emptySlice()` functions: PR [#1696](https://github.com/tact-lang/tact/pull/1696)
 - The `Int.toString` function now consumes up to 64% less gas: PR [#1837](https://github.com/tact-lang/tact/pull/1837)

docs/src/content/docs/ref/core-addresses.mdx

@@ -334,6 +334,80 @@ let community: Address = address("UQDpXLZKrkHsOuE_C1aS69C697wE568vTnqSeRfBXZfvmV
 let fizz: String = community.toString();
 ```
 
+## BasechainAddress
+
+<Badge text="Available since Tact 1.6" variant="tip" size="medium"/><p/>
+
+```tact
+struct BasechainAddress {
+    hash: Int?;
+}
+```
+
+Struct representing a basechain address.
+
+A basechain address (workchain $0$) can be either empty (null hash) or contain a 256-bit hash value.
+
+## emptyBasechainAddress
+
+<Badge text="Available since Tact 1.6" variant="tip" size="medium"/><p/>
+
+```tact
+inline fun emptyBasechainAddress(): BasechainAddress;
+```
+
+Creates and returns an empty basechain address with a null hash.
+
+When serialized, an empty basechain address is represented as `addr_none`.
+
+Usage example:
+
+```tact
+fun example() {
+    let emptyAddr: BasechainAddress = emptyBasechainAddress();
+    emptyAddr.hash == null; // true
+}
+```
+
+## newBasechainAddress
+
+<Badge text="Available since Tact 1.6" variant="tip" size="medium"/><p/>
+
+```tact
+inline fun newBasechainAddress(hash: Int): BasechainAddress;
+```
+
+Creates and returns a new basechain address with the specified hash value.
+
+Usage example:
+
+```tact
+fun example() {
+    let addr: BasechainAddress = newBasechainAddress(0x83dfd552e63729b472fcbcc8c45ebcc6691702558b68ec7527e1ba403a0f31a8);
+}
+```
+
+## contractBasechainAddress
+
+<Badge text="Available since Tact 1.6" variant="tip" size="medium"/><p/>
+
+```tact
+inline fun contractBasechainAddress(s: StateInit): BasechainAddress;
+```
+
+Creates and returns a basechain address derived from a contract's `StateInit` (code and data).
+
+Usage example:
+
+```tact
+fun example() {
+    let code: Cell = loadCell(); // load contract code
+    let data: Cell = loadCell(); // load contract data
+    let state: StateInit = StateInit { code, data };
+    let addr: BasechainAddress = contractBasechainAddress(state);
+}
+```
+
 [p]: /book/types#primitive-types
 [bool]: /book/types#booleans
 [int]: /book/integers

docs/src/content/docs/ref/core-cells.mdx

@@ -468,6 +468,31 @@ let b: Builder = beginCell();
 let fizz: Builder = b.storeAddress(myAddress());
 ```
 
+### Builder.storeBasechainAddress
+
+<Badge text="Available since Tact 1.6" variant="tip" size="medium"/><p/>
+
+```tact
+extends fun storeBasechainAddress(self: Builder, address: BasechainAddress): Builder;
+```
+
+Extension function for the [`Builder{:tact}`][builder] type.
+
+Stores the basechain `address` in the copy of the [`Builder{:tact}`][builder] and returns that copy.
+
+If the address has a `null` hash, stores $0b00$ (`addr_none`).
+Otherwise, store the full address with prefix $0b100$ followed by workchain ($0$) and the 256-bit hash.
+
+Usage example:
+
+```tact
+fun example() {
+    let addr: BasechainAddress = newBasechainAddress(0x83dfd552e63729b472fcbcc8c45ebcc6691702558b68ec7527e1ba403a0f31a8);
+    let b: Builder = beginCell();
+    let b2: Builder = b.storeBasechainAddress(addr);
+}
+```
+
 ### Builder.storeRef
 
 ```tact