Fix incremental compilation

CHANGELOG.md

@@ -10,6 +10,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Force files to be opened as UTF-8
 - Added a new solidity compiler setting `use_latest_patch` in brownie-config.yaml to use the latest patch version of a compiler based on the pragma version of the contract.
 - Add cli flag `-r` for raising exceptions to the caller instead of doing a system exit.
+### Fixed
+- Fix incremental compilation failing because of mismatching compiler versions
 
 ## [1.17.2](https://github.com/eth-brownie/brownie/tree/v1.17.2) - 2021-12-04
 ### Changed

brownie/project/main.py

@@ -291,17 +291,19 @@ def _compare_build_json(self, contract_name: str) -> bool:
         if build_json["sha1"] != sha1(source.encode()).hexdigest():
             return True
         # compare compiler settings
-        if _compare_settings(config, build_json["compiler"]):
-            return True
         if build_json["language"] == "Solidity":
             # compare solc-specific compiler settings
             solc_config = config["solc"].copy()
             solc_config["remappings"] = None
-            if _compare_settings(solc_config, build_json["compiler"]):
+            if not _solidity_compiler_equal(solc_config, build_json["compiler"]):
                 return True
             # compare solc pragma against compiled version
             if Version(build_json["compiler"]["version"]) not in get_pragma_spec(source):
                 return True
+        else:
+            vyper_config = config["vyper"].copy()
+            if not _vyper_compiler_equal(vyper_config, build_json["compiler"]):
+                return True
         return False
 
     def _compile_interfaces(self, compiled_hashes: Dict) -> None:
@@ -950,6 +952,22 @@ def _compare_settings(left: Dict, right: Dict) -> bool:
     )
 
 
+def _normalize_solidity_version(version: str) -> str:
+    return version.split("+")[0]
+
+
+def _solidity_compiler_equal(config: dict, build: dict) -> bool:
+    return (
+        config["version"] is None
+        or _normalize_solidity_version(config["version"])
+        == _normalize_solidity_version(build["version"])
+    ) and config["optimizer"] == build["optimizer"]
+
+
+def _vyper_compiler_equal(config: dict, build: dict) -> bool:
+    return config["version"] is None or config["version"] == build["version"]
+
+
 def _load_sources(project_path: Path, subfolder: str, allow_json: bool) -> Dict:
     contract_sources: Dict = {}
     suffixes: Tuple = (".sol", ".vy")