Adds support for the EVM version "Paris".

Deprecates `block.difficulty` and disallow `difficulty()` in inline assembly for EVM versions >= paris.
The change is due to the renaming introduced by EIP-4399 (see: https://eips.ethereum.org/EIPS/eip-4399).
Introduces `block.prevrandao` in Solidity and `prevrandao()` in inline assembly for EVM versions >= paris.

Co-authored-by: Alex Beregszaszi <alex@rtfs.hu>
Co-authored-by: Daniel <daniel@ekpyron.org>
Co-authored-by: matheusaaguiar <95899911+matheusaaguiar@users.noreply.github.com>
Co-authored-by: Nikola Matić <nikola.matic@ethereum.org>

test/libsolidity/syntaxTests/inlineAssembly/difficulty_builtin_pre_paris.sol

@@ -0,0 +1,14 @@
+contract C {
+    function f() public view returns (uint256) {
+        return block.difficulty;
+    }
+
+    function g() public view returns (uint256 ret) {
+        assembly {
+            ret := difficulty()
+        }
+    }
+}
+// ====
+// EVMVersion: <paris
+// ----

test/libsolidity/syntaxTests/inlineAssembly/difficulty_disallowed_function_pre_paris.sol

@@ -0,0 +1,21 @@
+contract C {
+    function f() public view returns (uint256 ret) {
+        assembly {
+            let difficulty := sload(0)
+            ret := difficulty
+        }
+    }
+
+    function g() public pure returns (uint256 ret) {
+        assembly {
+            function difficulty() -> r {
+                r := 1000
+            }
+            ret := difficulty()
+        }
+    }
+}
+// ====
+// EVMVersion: <paris
+// ----
+// ParserError 5568: (101-111): Cannot use builtin function name "difficulty" as identifier name.

test/libsolidity/syntaxTests/inlineAssembly/difficulty_magic_block_warn_post_paris.sol

@@ -0,0 +1,9 @@
+contract C {
+    function f() public view returns (uint256) {
+        return block.difficulty;
+    }
+}
+// ====
+// EVMVersion: >=paris
+// ----
+// Warning 8417: (77-93): Since the VM version paris, "difficulty" was replaced by "prevrandao", which now returns a random number based on the beacon chain.

test/libsolidity/syntaxTests/inlineAssembly/difficulty_nobuiltin_post_paris.sol

@@ -0,0 +1,12 @@
+contract C {
+    function f() public {
+        assembly {
+            pop(difficulty())
+        }
+    }
+}
+// ====
+// EVMVersion: >=paris
+// ----
+// DeclarationError 4619: (74-84): Function "difficulty" not found.
+// TypeError 3950: (74-86): Expected expression to evaluate to one value, but got 0 values instead.

test/libsolidity/syntaxTests/inlineAssembly/difficulty_reserved_post_paris.sol

@@ -0,0 +1,22 @@
+contract C {
+    function f() public view returns (uint256 ret) {
+        assembly {
+            let difficulty := sload(0)
+            ret := difficulty
+        }
+    }
+
+    function g() public pure returns (uint256 ret) {
+        assembly {
+            function difficulty() -> r {
+                r := 1000
+            }
+            ret := difficulty()
+        }
+    }
+}
+// ====
+// EVMVersion: >=paris
+// ----
+// DeclarationError 5017: (101-111): The identifier "difficulty" is reserved and can not be used.
+// DeclarationError 5017: (255-323): The identifier "difficulty" is reserved and can not be used.

test/libsolidity/syntaxTests/inlineAssembly/prevrandao_allowed_function_pre_paris.sol

@@ -0,0 +1,20 @@
+contract C {
+    function f() public view returns (uint256 ret) {
+        assembly {
+            let prevrandao := sload(0)
+            ret := prevrandao
+        }
+    }
+
+    function g() public pure returns (uint256 ret) {
+        assembly {
+            function prevrandao() -> r {
+                r := 1000
+            }
+            ret := prevrandao()
+        }
+    }
+}
+// ====
+// EVMVersion: <paris
+// ----

test/libsolidity/syntaxTests/inlineAssembly/prevrandao_builtin_post_paris.sol

@@ -0,0 +1,14 @@
+contract C {
+    function f() public view returns (uint256) {
+        return block.prevrandao;
+    }
+
+    function g() public view returns (uint256 ret) {
+        assembly {
+            ret := prevrandao()
+        }
+    }
+}
+// ====
+// EVMVersion: >=paris
+// ----

test/libsolidity/syntaxTests/inlineAssembly/prevrandao_disallowed_function_post_paris.sol

@@ -0,0 +1,21 @@
+contract C {
+    function f() public view returns (uint256 ret) {
+        assembly {
+            let prevrandao := sload(0)
+            ret := prevrandao
+        }
+    }
+
+    function g() public pure returns (uint256 ret) {
+        assembly {
+            function prevrandao() -> r {
+                r := 1000
+            }
+            ret := prevrandao()
+        }
+    }
+}
+// ====
+// EVMVersion: >=paris
+// ----
+// ParserError 5568: (101-111): Cannot use builtin function name "prevrandao" as identifier name.

test/libsolidity/syntaxTests/inlineAssembly/prevrandao_magic_block_warn_pre_paris.sol

@@ -0,0 +1,9 @@
+contract C {
+    function f() public view returns (uint256) {
+        return block.prevrandao;
+    }
+}
+// ====
+// EVMVersion: <paris
+// ----
+// Warning 9432: (77-93): "prevrandao" is not supported by the VM version and will be treated as "difficulty".

test/libsolidity/syntaxTests/inlineAssembly/prevrandao_nobuitin_pre_paris.sol

@@ -0,0 +1,12 @@
+contract C {
+    function f() public {
+        assembly {
+            pop(prevrandao())
+        }
+    }
+}
+// ====
+// EVMVersion: <paris
+// ----
+// DeclarationError 4619: (74-84): Function "prevrandao" not found.
+// TypeError 3950: (74-86): Expected expression to evaluate to one value, but got 0 values instead.