remove builtin random function (#1041)

Signed-off-by: Cyrill Leutwiler <bigcyrill@hotmail.com>

docs/language/builtins.rst

@@ -31,10 +31,6 @@ Returns the blockhash for a particular block. This not possible for the current
 block, or any block except for the most recent 256. Do not use this a source of
 randomness unless you know what you are doing.
 
-.. note::
-    This function is not available on Parity Substrate. When using Parity Substrate,
-    use ``random()`` as a source of random data.
-
 .. note::
     This function is not available on Solana. There is the
     `recent block hashes account <https://edge.docs.solana.com/developing/runtime-facilities/sysvars#recentblockhashes>`_
@@ -44,17 +40,6 @@ randomness unless you know what you are doing.
     - It does not give any slot of block number, so it is not possible to provide a matching
       function signature.
 
-random(bytes subject) returns (bytes32)
-+++++++++++++++++++++++++++++++++++++++
-
-Returns random bytes based on the subject. The same subject for the same transaction
-will return the same random bytes, so the result is deterministic. The chain has
-a ``max_subject_len``, and if *subject* exceeds that, the transaction will be aborted.
-
-.. note::
-
-    This function is only available on Parity Substrate.
-
 ``msg`` properties
 ++++++++++++++++++
 

src/sema/builtin.rs

@@ -31,7 +31,7 @@ pub struct Prototype {
 }
 
 // A list of all Solidity builtins functions
-static BUILTIN_FUNCTIONS: Lazy<[Prototype; 28]> = Lazy::new(|| {
+static BUILTIN_FUNCTIONS: Lazy<[Prototype; 27]> = Lazy::new(|| {
     [
         Prototype {
             builtin: Builtin::Assert,
@@ -187,17 +187,6 @@ static BUILTIN_FUNCTIONS: Lazy<[Prototype; 28]> = Lazy::new(|| {
             doc: "Returns the block hash for given block number",
             constant: false,
         },
-        Prototype {
-            builtin: Builtin::Random,
-            namespace: None,
-            method: None,
-            name: "random",
-            params: vec![Type::DynamicBytes],
-            ret: vec![Type::Bytes(32)],
-            target: vec![Target::default_substrate()],
-            doc: "Returns deterministic random bytes",
-            constant: false,
-        },
         Prototype {
             builtin: Builtin::AbiDecode,
             namespace: Some("abi"),

tests/substrate_tests/builtins.rs

@@ -416,21 +416,6 @@ fn functions() {
     );
 
     runtime.function("test", Vec::new());
-
-    let mut runtime = build_solidity(
-        r##"
-        contract c {
-            function test() public {
-                bytes32 o = random(
-                    "abcd"
-                );
-
-                assert(o == hex"429ccf3ebce07f0c6d7cd0d1dead74459f753cdf53ed8359e42728042a91c39c");
-            }
-        }"##,
-    );
-
-    runtime.function("test", Vec::new());
 }
 
 #[test]