feat: improve warnings, refactor vyper_warn() (#3800)

* add source information to vyper_warn() to give more helpful warnings
* add source information to the struct instantiation warning

tests/functional/syntax/test_structs.py

@@ -594,4 +594,4 @@ def foo():
         expected += "Use kwargs instead e.g. Foo(a=1, b=2)"
 
         assert len(w) == 1
-        assert str(w[0].message) == expected
+        assert str(w[0].message).startswith(expected)

vyper/ast/parse.py

@@ -1,6 +1,5 @@
 import ast as python_ast
 import tokenize
-import warnings
 from decimal import Decimal
 from typing import Any, Dict, List, Optional, Union, cast
 
@@ -11,6 +10,7 @@
 from vyper.compiler.settings import Settings
 from vyper.exceptions import CompilerPanic, ParserException, SyntaxException
 from vyper.typing import ModificationOffsets
+from vyper.utils import vyper_warn
 
 
 def parse_to_ast(*args: Any, **kwargs: Any) -> vy_ast.Module:
@@ -348,7 +348,10 @@ def visit_Call(self, node):
             msg = "Instantiating a struct using a dictionary is deprecated "
             msg += "as of v0.4.0 and will be disallowed in a future release. "
             msg += "Use kwargs instead e.g. Foo(a=1, b=2)"
-            warnings.warn(msg, stacklevel=2)
+
+            # add full_source_code so that str(VyperException(msg, node)) works
+            node.full_source_code = self._source_code
+            vyper_warn(msg, node)
 
             dict_ = node.args[0]
             kw_list = []

vyper/builtins/functions.py

@@ -1234,7 +1234,9 @@ class SelfDestruct(BuiltinFunctionT):
     @process_inputs
     def build_IR(self, expr, args, kwargs, context):
         if not self._warned:
-            vyper_warn("`selfdestruct` is deprecated! The opcode is no longer recommended for use.")
+            vyper_warn(
+                "`selfdestruct` is deprecated! The opcode is no longer recommended for use.", expr
+            )
             self._warned = True
 
         context.check_is_not_constant("selfdestruct", expr)
@@ -1337,7 +1339,7 @@ class BitwiseAnd(BuiltinFunctionT):
 
     def _try_fold(self, node):
         if not self.__class__._warned:
-            vyper_warn("`bitwise_and()` is deprecated! Please use the & operator instead.")
+            vyper_warn("`bitwise_and()` is deprecated! Please use the & operator instead.", node)
             self.__class__._warned = True
 
         validate_call_args(node, 2)
@@ -1362,7 +1364,7 @@ class BitwiseOr(BuiltinFunctionT):
 
     def _try_fold(self, node):
         if not self.__class__._warned:
-            vyper_warn("`bitwise_or()` is deprecated! Please use the | operator instead.")
+            vyper_warn("`bitwise_or()` is deprecated! Please use the | operator instead.", node)
             self.__class__._warned = True
 
         validate_call_args(node, 2)
@@ -1387,7 +1389,7 @@ class BitwiseXor(BuiltinFunctionT):
 
     def _try_fold(self, node):
         if not self.__class__._warned:
-            vyper_warn("`bitwise_xor()` is deprecated! Please use the ^ operator instead.")
+            vyper_warn("`bitwise_xor()` is deprecated! Please use the ^ operator instead.", node)
             self.__class__._warned = True
 
         validate_call_args(node, 2)
@@ -1412,7 +1414,7 @@ class BitwiseNot(BuiltinFunctionT):
 
     def _try_fold(self, node):
         if not self.__class__._warned:
-            vyper_warn("`bitwise_not()` is deprecated! Please use the ~ operator instead.")
+            vyper_warn("`bitwise_not()` is deprecated! Please use the ~ operator instead.", node)
             self.__class__._warned = True
 
         validate_call_args(node, 1)
@@ -1438,7 +1440,7 @@ class Shift(BuiltinFunctionT):
 
     def _try_fold(self, node):
         if not self.__class__._warned:
-            vyper_warn("`shift()` is deprecated! Please use the << or >> operator instead.")
+            vyper_warn("`shift()` is deprecated! Please use the << or >> operator instead.", node)
             self.__class__._warned = True
 
         validate_call_args(node, 2)
@@ -1764,7 +1766,9 @@ class CreateForwarderTo(CreateMinimalProxyTo):
 
     def build_IR(self, expr, context):
         if not self._warned:
-            vyper_warn("`create_forwarder_to` is a deprecated alias of `create_minimal_proxy_to`!")
+            vyper_warn(
+                "`create_forwarder_to` is a deprecated alias of `create_minimal_proxy_to`!", expr
+            )
             self._warned = True
 
         return super().build_IR(expr, context)
@@ -2265,7 +2269,7 @@ class Breakpoint(BuiltinFunctionT):
 
     def fetch_call_return(self, node):
         if not self._warned:
-            vyper_warn("`breakpoint` should only be used for debugging!\n" + node._annotated_source)
+            vyper_warn("`breakpoint` should only be used for debugging!", node)
             self._warned = True
 
         return None
@@ -2285,7 +2289,7 @@ class Print(BuiltinFunctionT):
 
     def fetch_call_return(self, node):
         if not self._warned:
-            vyper_warn("`print` should only be used for debugging!\n" + node._annotated_source)
+            vyper_warn("`print` should only be used for debugging!", node)
             self._warned = True
 
         return None

vyper/codegen/expr.py

@@ -34,7 +34,6 @@
     TypeCheckFailure,
     TypeMismatch,
     UnimplementedException,
-    VyperException,
     tag_exceptions,
 )
 from vyper.semantics.types import (
@@ -280,21 +279,15 @@ def parse_Attribute(self):
                 return IRnode.from_list(["gas"], typ=UINT256_T)
             elif key == "block.prevrandao":
                 if not version_check(begin="paris"):
-                    warning = VyperException(
-                        "tried to use block.prevrandao in pre-Paris "
-                        "environment! Suggest using block.difficulty instead.",
-                        self.expr,
-                    )
-                    vyper_warn(str(warning))
+                    warning = "tried to use block.prevrandao in pre-Paris "
+                    warning += "environment! Suggest using block.difficulty instead."
+                    vyper_warn(warning, self.expr)
                 return IRnode.from_list(["prevrandao"], typ=UINT256_T)
             elif key == "block.difficulty":
                 if version_check(begin="paris"):
-                    warning = VyperException(
-                        "tried to use block.difficulty in post-Paris "
-                        "environment! Suggest using block.prevrandao instead.",
-                        self.expr,
-                    )
-                    vyper_warn(str(warning))
+                    warning = "tried to use block.difficulty in post-Paris "
+                    warning += "environment! Suggest using block.prevrandao instead."
+                    vyper_warn(warning, self.expr)
                 return IRnode.from_list(["difficulty"], typ=UINT256_T)
             elif key == "block.timestamp":
                 return IRnode.from_list(["timestamp"], typ=UINT256_T)

vyper/utils.py

@@ -9,7 +9,7 @@
 import warnings
 from typing import Generic, List, TypeVar, Union
 
-from vyper.exceptions import CompilerPanic, DecimalOverrideException, InvalidLiteral
+from vyper.exceptions import CompilerPanic, DecimalOverrideException, InvalidLiteral, VyperException
 
 _T = TypeVar("_T")
 
@@ -208,8 +208,11 @@ def trace(n=5, out=sys.stderr):
 
 
 # print a warning
-def vyper_warn(msg, prefix="Warning: ", file_=sys.stderr):
-    print(f"{prefix}{msg}", file=file_)
+def vyper_warn(msg, node=None):
+    if node is not None:
+        # use VyperException for its formatting abilities
+        msg = str(VyperException(msg, node))
+    warnings.warn(msg, stacklevel=2)
 
 
 # converts a signature like Func(bool,uint256,address) to its 4 byte method ID