Tests and Changelog for basefee.

Author: hrkrshnn

Changelog.md

@@ -1,6 +1,8 @@
 ### 0.8.7 (unreleased)
 
 Language Features:
+ * Introduce global ``block.basefee`` for retrieving the base fee of the current block.
+ * Yul: Introduce builtin ``basefee()`` for retrieving the base fee of the current block.
 
 
 Compiler Features:

test/libsolidity/semanticTests/state/block_basefee.sol

@@ -0,0 +1,18 @@
+contract C {
+    function f() public view returns (uint) {
+        return block.basefee;
+    }
+    function g() public view returns (uint ret) {
+        assembly {
+            ret := basefee()
+        }
+    }
+}
+// ====
+// EVMVersion: >=london
+// compileViaYul: also
+// ----
+// f() -> 7
+// g() -> 7
+// f() -> 7
+// g() -> 7

test/libsolidity/syntaxTests/types/magic_block_basefee_error.sol

@@ -0,0 +1,15 @@
+contract C {
+    function f() public view returns (uint) {
+        return block.basefee;
+    }
+    function g() public view returns (uint ret) {
+        assembly {
+            ret := basefee()
+        }
+    }
+}
+// ====
+// EVMVersion: =berlin
+// ----
+// TypeError 5921: (74-87): "basefee" is not supported by the VM version.
+// TypeError 5430: (183-190): The "basefee" instruction is only available for London-compatible VMs (you are currently compiling for "berlin").

test/libsolidity/syntaxTests/types/magic_block_london.sol

@@ -0,0 +1,13 @@
+contract C {
+    function f() public view returns (uint) {
+        return block.basefee;
+    }
+    function g() public view returns (uint ret) {
+        assembly {
+            ret := basefee()
+        }
+    }
+}
+// ====
+// EVMVersion: >=london
+// ----

test/libsolidity/syntaxTests/viewPureChecker/basefee_not_pure.sol

@@ -0,0 +1,13 @@
+contract C {
+    function f() public pure {
+        assembly { pop(basefee()) }
+    }
+    function g() public pure returns (uint) {
+        return block.basefee;
+    }
+}
+// ====
+// EVMVersion: >=london
+// ----
+// TypeError 2527: (67-76): Function declared as pure, but this expression (potentially) reads from the environment or state and thus requires "view".
+// TypeError 2527: (147-160): Function declared as pure, but this expression (potentially) reads from the environment or state and thus requires "view".

test/libyul/objectCompiler/dataoffset_data.yul

@@ -13,5 +13,5 @@ object "a" {
 // stop
 // data_acaf3289d7b601cbd114fb36c4d29c85bbfd5e133f14cb355c3fd8d99367964f 48656c6c6f2c20576f726c6421
 // Bytecode: 6006600055fe48656c6c6f2c20576f726c6421
-// Opcodes: PUSH1 0x6 PUSH1 0x0 SSTORE INVALID 0x48 PUSH6 0x6C6C6F2C2057 PUSH16 0x726C6421000000000000000000000000
+// Opcodes: PUSH1 0x6 PUSH1 0x0 SSTORE INVALID BASEFEE PUSH6 0x6C6C6F2C2057 PUSH16 0x726C6421000000000000000000000000
 // SourceMappings: 32:19:0:-:0;29:1;22:30