feat: Allow emission of diagnostics inside GuppyError (#553)

Closes #538.

* Allow to pass a `Diagnostic` object to `GuppyError` instead of an
error message
* The old error reporting system remains untouched until we have
migrated everything to the new diagnostics system
* Adds a `TypeMismatchError` diagnostic as a test to ensure that the
pipeline works

guppylang/checker/expr_checker.py

@@ -24,8 +24,8 @@
 import sys
 import traceback
 from contextlib import suppress
-from dataclasses import replace
-from typing import Any, NoReturn, cast
+from dataclasses import dataclass, replace
+from typing import Any, ClassVar, NoReturn, cast
 
 from guppylang.ast_util import (
     AstNode,
@@ -51,6 +51,7 @@
 from guppylang.definition.module import ModuleDef
 from guppylang.definition.ty import TypeDef
 from guppylang.definition.value import CallableDef, ValueDef
+from guppylang.diagnostic import Error
 from guppylang.error import (
     GuppyError,
     GuppyTypeError,
@@ -135,6 +136,18 @@
 }  # fmt: skip
 
 
+@dataclass(frozen=True)
+class TypeMismatchError(Error):
+    """Error diagnostic for expressions with the wrong type."""
+
+    expected: Type
+    actual: Type
+    kind: str = "expression"
+
+    title: ClassVar[str] = "Type mismatch"
+    span_label: ClassVar[str] = "Expected {kind} of type `{expected}`, got `{actual}`"
+
+
 class ExprChecker(AstVisitor[tuple[ast.expr, Subst]]):
     """Checks an expression against a type and produces a new type-annotated AST.
 
@@ -164,9 +177,7 @@ def _fail(
             _, actual = self._synthesize(actual, allow_free_vars=True)
         if loc is None:
             raise InternalGuppyError("Failure location is required")
-        raise GuppyTypeError(
-            f"Expected {self._kind} of type `{expected}`, got `{actual}`", loc
-        )
+        raise GuppyTypeError(TypeMismatchError(loc, expected, actual))
 
     def check(
         self, expr: ast.expr, ty: Type, kind: str = "expression"
@@ -731,7 +742,7 @@ def check_type_against(
         unquantified, free_vars = act.unquantified()
         subst = unify(exp, unquantified, {})
         if subst is None:
-            raise GuppyTypeError(f"Expected {kind} of type `{exp}`, got `{act}`", node)
+            raise GuppyTypeError(TypeMismatchError(node, exp, act, kind))
         # Check that we have found a valid instantiation for all params
         for i, v in enumerate(free_vars):
             if v not in subst:
@@ -760,7 +771,7 @@ def check_type_against(
     assert not act.unsolved_vars
     subst = unify(exp, act, {})
     if subst is None:
-        raise GuppyTypeError(f"Expected {kind} of type `{exp}`, got `{act}`", node)
+        raise GuppyTypeError(TypeMismatchError(node, exp, act, kind))
     return subst, []
 
 
@@ -927,17 +938,15 @@ def check_call(
         synth, inst = res
         subst = unify(ty, synth, {})
         if subst is None:
-            raise GuppyTypeError(f"Expected {kind} of type `{ty}`, got `{synth}`", node)
+            raise GuppyTypeError(TypeMismatchError(node, ty, synth, kind))
         return inputs, subst, inst
 
     # If synthesis fails, we try again, this time also using information from the
     # expected return type
     unquantified, free_vars = func_ty.unquantified()
     subst = unify(ty, unquantified.output, {})
     if subst is None:
-        raise GuppyTypeError(
-            f"Expected {kind} of type `{ty}`, got `{unquantified.output}`", node
-        )
+        raise GuppyTypeError(TypeMismatchError(node, ty, unquantified.output, kind))
 
     # Try to infer more by checking against the arguments
     inputs, subst = type_check_args(inputs, unquantified, subst, ctx, node)

guppylang/diagnostic.py

@@ -117,6 +117,16 @@ def add_sub_diagnostic(self, sub: "SubDiagnostic") -> Self:
         self.children.append(sub)
         return self
 
+    @property
+    def rendered_message(self) -> str | None:
+        """The message of this diagnostic with formatted placeholders if provided."""
+        return self._render(self.message)
+
+    @property
+    def rendered_span_label(self) -> str | None:
+        """The span label of this diagnostic with formatted placeholders if provided."""
+        return self._render(self.span_label)
+
 
 @runtime_checkable
 @dataclass(frozen=True)

guppylang/error.py

@@ -7,11 +7,14 @@
 from contextlib import contextmanager
 from dataclasses import dataclass, field
 from types import TracebackType
-from typing import Any, TypeVar, cast
+from typing import TYPE_CHECKING, Any, TypeVar, cast
 
 from guppylang.ast_util import AstNode, get_file, get_line_offset, get_source
 from guppylang.ipython_inspect import is_running_ipython
 
+if TYPE_CHECKING:
+    from guppylang.diagnostic import Diagnostic
+
 
 @dataclass(frozen=True)
 class SourceLoc:
@@ -49,7 +52,7 @@ class GuppyError(Exception):
     The error message can also refer to AST locations using format placeholders `{0}`,
     `{1}`, etc. and passing the corresponding AST nodes to `locs_in_msg`."""
 
-    raw_msg: str
+    raw_msg: "str | Diagnostic"
     location: AstNode | None = None
     # The message can also refer to AST locations using format placeholders `{0}`, `{1}`
     locs_in_msg: Sequence[AstNode | None] = field(default_factory=list)
@@ -59,6 +62,7 @@ def get_msg(self) -> str:
 
         A line offset is needed to translate AST locations mentioned in the message into
         source locations in the actual file."""
+        assert isinstance(self.raw_msg, str)
         return self.raw_msg.format(
             *(
                 SourceLoc.from_ast(loc) if loc is not None else "???"
@@ -157,6 +161,18 @@ def hook(
         excty: type[BaseException], err: BaseException, traceback: TracebackType | None
     ) -> None:
         """Custom `excepthook` that intercepts `GuppyExceptions` for pretty printing."""
+        from guppylang.diagnostic import Diagnostic, DiagnosticsRenderer
+
+        # Check for errors using our new diagnostics system
+        if isinstance(err, GuppyError) and isinstance(err.raw_msg, Diagnostic):
+            from guppylang.decorator import guppy
+
+            renderer = DiagnosticsRenderer(guppy._sources)
+            renderer.render_diagnostic(err.raw_msg)
+            sys.stderr.write("\n".join(renderer.buffer))
+            sys.stderr.write("\n\nGuppy compilation failed due to 1 previous error\n")
+            return
+
         # Fall back to default hook if it's not a GuppyException or we're missing an
         # error location
         if not isinstance(err, GuppyError) or err.location is None:

tests/error/array_errors/new_array_elem_mismatch2.err

@@ -1,7 +1,8 @@
-Guppy compilation failed. Error in file $FILE:13
+Error: Type mismatch (at $FILE:13:13)
+   | 
+11 | @guppy(module)
+12 | def main() -> None:
+13 |     array(1, False)
+   |              ^^^^^ Expected expression of type `int`, got `bool`
 
-11:    @guppy(module)
-12:    def main() -> None:
-13:        array(1, False)
-                    ^^^^^
-GuppyTypeError: Expected expression of type `int`, got `bool`
+Guppy compilation failed due to 1 previous error

tests/error/inout_errors/conflict.err

@@ -1,7 +1,9 @@
-Guppy compilation failed. Error in file $FILE:19
+Error: Type mismatch (at $FILE:19:11)
+   | 
+17 | @guppy(module)
+18 | def test() -> Callable[[qubit @owned], qubit]:
+19 |     return foo
+   |            ^^^ Expected return value of type `qubit @owned -> qubit`, got
+   |                `qubit -> qubit`
 
-17:    @guppy(module)
-18:    def test() -> Callable[[qubit @owned], qubit]:
-19:        return foo
-                  ^^^
-GuppyTypeError: Expected return value of type `qubit @owned -> qubit`, got `qubit -> qubit`
+Guppy compilation failed due to 1 previous error

tests/error/misc_errors/implicit_module_error.err

@@ -1,7 +1,8 @@
-Guppy compilation failed. Error in file $FILE:6
+Error: Type mismatch (at $FILE:6:11)
+  | 
+4 | @guppy
+5 | def foo() -> int:
+6 |     return 1.0
+  |            ^^^ Expected return value of type `int`, got `float`
 
-4:    @guppy
-5:    def foo() -> int:
-6:        return 1.0
-                 ^^^
-GuppyTypeError: Expected return value of type `int`, got `float`
+Guppy compilation failed due to 1 previous error

tests/error/poly_errors/arg_mismatch1.err

@@ -1,7 +1,8 @@
-Guppy compilation failed. Error in file $FILE:17
+Error: Type mismatch (at $FILE:17:11)
+   | 
+15 | @guppy(module)
+16 | def main(x: bool, y: tuple[bool]) -> None:
+17 |     foo(x, y)
+   |            ^ Expected argument of type `bool`, got `(bool)`
 
-15:    @guppy(module)
-16:    def main(x: bool, y: tuple[bool]) -> None:
-17:        foo(x, y)
-                  ^
-GuppyTypeError: Expected argument of type `bool`, got `(bool)`
+Guppy compilation failed due to 1 previous error

tests/error/poly_errors/arg_mismatch2.err

@@ -1,7 +1,8 @@
-Guppy compilation failed. Error in file $FILE:17
+Error: Type mismatch (at $FILE:17:8)
+   | 
+15 | @guppy(module)
+16 | def main() -> None:
+17 |     foo(False)
+   |         ^^^^^ Expected argument of type `(?T, ?T)`, got `bool`
 
-15:    @guppy(module)
-16:    def main() -> None:
-17:        foo(False)
-               ^^^^^
-GuppyTypeError: Expected argument of type `(?T, ?T)`, got `bool`
+Guppy compilation failed due to 1 previous error

tests/error/poly_errors/arg_mismatch3.err

@@ -1,7 +1,9 @@
-Guppy compilation failed. Error in file $FILE:17
+Error: Type mismatch (at $FILE:17:11)
+   | 
+15 | @guppy(module)
+16 | def main(x: array[int, 42], y: array[int, 43]) -> None:
+17 |     foo(x, y)
+   |            ^ Expected argument of type `array[int, 42]`, got `array[int,
+   |              43]`
 
-15:    @guppy(module)
-16:    def main(x: array[int, 42], y: array[int, 43]) -> None:
-17:        foo(x, y)
-                  ^
-GuppyTypeError: Expected argument of type `array[int, 42]`, got `array[int, 43]`
+Guppy compilation failed due to 1 previous error

tests/error/poly_errors/inst_return_mismatch.err

@@ -1,7 +1,8 @@
-Guppy compilation failed. Error in file $FILE:17
+Error: Type mismatch (at $FILE:17:14)
+   | 
+15 | @guppy(module)
+16 | def main(x: bool) -> None:
+17 |     y: None = foo(x)
+   |               ^^^^^^ Expected expression of type `None`, got `bool`
 
-15:    @guppy(module)
-16:    def main(x: bool) -> None:
-17:        y: None = foo(x)
-                     ^^^^^^
-GuppyTypeError: Expected expression of type `None`, got `bool`
+Guppy compilation failed due to 1 previous error

tests/error/poly_errors/inst_return_mismatch_nested.err

@@ -1,7 +1,8 @@
-Guppy compilation failed. Error in file $FILE:17
+Error: Type mismatch (at $FILE:17:14)
+   | 
+15 | @guppy(module)
+16 | def main(x: bool) -> None:
+17 |     y: None = foo(foo(foo(x)))
+   |               ^^^^^^^^^^^^^^^^ Expected expression of type `None`, got `bool`
 
-15:    @guppy(module)
-16:    def main(x: bool) -> None:
-17:        y: None = foo(foo(foo(x)))
-                     ^^^^^^^^^^^^^^^^
-GuppyTypeError: Expected expression of type `None`, got `bool`
+Guppy compilation failed due to 1 previous error

tests/error/poly_errors/return_mismatch.err

@@ -1,7 +1,8 @@
-Guppy compilation failed. Error in file $FILE:17
+Error: Type mismatch (at $FILE:17:14)
+   | 
+15 | @guppy(module)
+16 | def main() -> None:
+17 |     x: bool = foo()
+   |               ^^^^^ Expected expression of type `bool`, got `(?T, ?T)`
 
-15:    @guppy(module)
-16:    def main() -> None:
-17:        x: bool = foo()
-                     ^^^^^
-GuppyTypeError: Expected expression of type `bool`, got `(?T, ?T)`
+Guppy compilation failed due to 1 previous error

tests/error/struct_errors/constructor_arg_mismatch.err

@@ -1,7 +1,8 @@
-Guppy compilation failed. Error in file $FILE:15
+Error: Type mismatch (at $FILE:15:13)
+   | 
+13 | @guppy(module)
+14 | def main() -> None:
+15 |     MyStruct(0)
+   |              ^ Expected argument of type `(int, int)`, got `int`
 
-13:    @guppy(module)
-14:    def main() -> None:
-15:        MyStruct(0)
-                    ^
-GuppyTypeError: Expected argument of type `(int, int)`, got `int`
+Guppy compilation failed due to 1 previous error

tests/error/struct_errors/constructor_arg_mismatch_poly.err

@@ -1,7 +1,8 @@
-Guppy compilation failed. Error in file $FILE:19
+Error: Type mismatch (at $FILE:19:16)
+   | 
+17 | @guppy(module)
+18 | def main() -> None:
+19 |     MyStruct(0, False)
+   |                 ^^^^^ Expected argument of type `int`, got `bool`
 
-17:    @guppy(module)
-18:    def main() -> None:
-19:        MyStruct(0, False)
-                       ^^^^^
-GuppyTypeError: Expected argument of type `int`, got `bool`
+Guppy compilation failed due to 1 previous error

tests/error/tensor_errors/type_mismatch.err

@@ -1,7 +1,8 @@
-Guppy compilation failed. Error in file $FILE:12
+Error: Type mismatch (at $FILE:12:26)
+   | 
+10 | @guppy(module)
+11 | def main() -> int:
+12 |     return (foo, foo)(42, False)
+   |                           ^^^^^ Expected argument of type `int`, got `bool`
 
-10:    @guppy(module)
-11:    def main() -> int:
-12:        return (foo, foo)(42, False)
-                                 ^^^^^
-GuppyTypeError: Expected argument of type `int`, got `bool`
+Guppy compilation failed due to 1 previous error

tests/error/type_errors/call_wrong_arg.err

@@ -1,7 +1,8 @@
-Guppy compilation failed. Error in file $FILE:6
+Error: Type mismatch (at $FILE:6:15)
+  | 
+4 | @compile_guppy
+5 | def foo(x: int) -> int:
+6 |     return foo(True)
+  |                ^^^^ Expected argument of type `int`, got `bool`
 
-4:    @compile_guppy
-5:    def foo(x: int) -> int:
-6:        return foo(True)
-                     ^^^^
-GuppyTypeError: Expected argument of type `int`, got `bool`
+Guppy compilation failed due to 1 previous error

tests/error/type_errors/fun_ty_mismatch_1.err

@@ -1,7 +1,9 @@
-Guppy compilation failed. Error in file $FILE:11
+Error: Type mismatch (at $FILE:11:11)
+   | 
+ 9 |         return x > 0
+10 | 
+11 |     return bar
+   |            ^^^ Expected return value of type `int -> int`, got `int ->
+   |                bool`
 
-9:         return x > 0
-10:    
-11:    return bar
-              ^^^
-GuppyTypeError: Expected return value of type `int -> int`, got `int -> bool`
+Guppy compilation failed due to 1 previous error

tests/error/type_errors/fun_ty_mismatch_2.err

@@ -1,7 +1,8 @@
-Guppy compilation failed. Error in file $FILE:11
+Error: Type mismatch (at $FILE:11:15)
+   | 
+ 9 |         return f()
+10 | 
+11 |     return bar(foo)
+   |                ^^^ Expected argument of type `() -> int`, got `int -> int`
 
-9:         return f()
-10:    
-11:    return bar(foo)
-                  ^^^
-GuppyTypeError: Expected argument of type `() -> int`, got `int -> int`
+Guppy compilation failed due to 1 previous error

tests/error/type_errors/fun_ty_mismatch_3.err

@@ -1,7 +1,8 @@
-Guppy compilation failed. Error in file $FILE:11
+Error: Type mismatch (at $FILE:11:15)
+   | 
+ 9 |         return f(42)
+10 | 
+11 |     return bar(foo)
+   |                ^^^ Expected argument of type `int -> bool`, got `int -> int`
 
-9:         return f(42)
-10:    
-11:    return bar(foo)
-                  ^^^
-GuppyTypeError: Expected argument of type `int -> bool`, got `int -> int`
+Guppy compilation failed due to 1 previous error