Set standard target address storage location

SRCs/src-14.md

@@ -25,7 +25,9 @@ The FuelVM provides an `LDC` instruction that is used by Sway's `std::execution:
 
 ### Required Behavior
 
-A proxy contract SHOULD maintain the address of its target in its storage and it SHOULD base proxy specific storage fields at `sha256("storage_SRC14")` to avoid collisions with target storage.
+The proxy contract MUST maintain the address of its target in its storage at slot `0x7bb458adc1d118713319a5baa00a2d049dd64d2916477d2688d76970c898cd55` (equivalent to `sha256("storage_SRC15_0")`).
+It SHOULD base other proxy specific storage fields at `sha256("storage_SRC14")` to avoid collisions with target storage.
+It MAY have its storage definition overlap with that of its target if necessary.
 
 The proxy contract MUST delegate any method call not part of its interface to the target contract.
 
@@ -37,7 +39,7 @@ The following functions MUST be implemented by a proxy contract to follow the SR
 
 #### `fn set_proxy_address(new_target: ContractId);`
 
-If a valid call is made to this function it MUST change the target of the proxy to the contract at `new_target`.
+If a valid call is made to this function it MUST change the target address of the proxy to `new_target`.
 This method SHOULD implement access controls such that the target can only be changed by a user that possesses the right permissions (typically the proxy owner).
 
 ## Rationale

examples/src14-simple-proxy/minimal/src/minimal.sw

@@ -7,6 +7,7 @@ use standards::src14::SRC14;
 // use sha256("storage_SRC14") as base to avoid collisions
 #[namespace(SRC14)]
 storage {
+    // target is as sha256("storage_SRC14_0")
     target: ContractId = ContractId::from(ZERO_B256),
 }
 

examples/src14-simple-proxy/owned/src/owned.sw

@@ -11,6 +11,7 @@ const INITIAL_OWNER: Identity = Identity::Address(Address::from(ZERO_B256));
 // use sha256("storage_SRC14") as base to avoid collisions
 #[namespace(SRC14)]
 storage {
+    // target is as sha256("storage_SRC14_0")
     target: ContractId = ContractId::from(ZERO_B256),
     owner: State = State::Initialized(INITIAL_OWNER),
 }

standards/src/src14.sw

@@ -21,3 +21,8 @@ abi SRC14 {
     #[storage(write)]
     fn set_proxy_target(new_target: ContractId);
 }
+
+/// The standard storage slot to store proxy target address.
+///
+/// Value is `sha256("storage_SRC14_0")`.
+pub const SRC14_TARGET_STORAGE: b256 = 0x7bb458adc1d118713319a5baa00a2d049dd64d2916477d2688d76970c898cd55;