fix: Allow string py expressions in result and panic (#759)

guppylang/std/_internal/checker.py

@@ -47,6 +47,7 @@
     is_sized_iter_type,
     nat_type,
     sized_iter_type,
+    string_type,
 )
 from guppylang.tys.const import Const, ConstValue
 from guppylang.tys.subst import Inst, Subst
@@ -318,6 +319,7 @@ class Hint(Note):
     def synthesize(self, args: list[ast.expr]) -> tuple[ast.expr, Type]:
         check_num_args(2, len(args), self.node)
         [tag, value] = args
+        tag, _ = ExprChecker(self.ctx).check(tag, string_type())
         if not isinstance(tag, ast.Constant) or not isinstance(tag.value, str):
             raise GuppyTypeError(ExpectedError(tag, "a string literal"))
         if len(tag.value.encode("utf-8")) > TAG_MAX_LEN:
@@ -375,6 +377,7 @@ def synthesize(self, args: list[ast.expr]) -> tuple[ast.expr, Type]:
                 err.add_sub_diagnostic(PanicChecker.NoMessageError.Suggestion(None))
                 raise GuppyTypeError(err)
             case [msg, *rest]:
+                msg, _ = ExprChecker(self.ctx).check(msg, string_type())
                 if not isinstance(msg, ast.Constant) or not isinstance(msg.value, str):
                     raise GuppyTypeError(ExpectedError(msg, "a string literal"))
 

tests/error/misc_errors/panic_msg_not_str.err

@@ -1,8 +1,8 @@
-Error: Expected a string literal (at $FILE:7:10)
+Error: Type mismatch (at $FILE:7:10)
   | 
 5 | @compile_guppy
 6 | def foo(x: int) -> None:
 7 |     panic((), x)
-  |           ^^ Expected a string literal
+  |           ^^ Expected expression of type `str`, got `()`
 
 Guppy compilation failed due to 1 previous error

tests/error/misc_errors/panic_tag_not_static.err

@@ -2,7 +2,7 @@ Error: Expected a string literal (at $FILE:7:10)
   | 
 5 | @compile_guppy
 6 | def foo(y: bool) -> None:
-7 |     panic("foo" + "bar", y)
-  |           ^^^^^^^^^^^^^ Expected a string literal
+7 |     panic("foo" if y else "bar", y)
+  |           ^^^^^^^^^^^^^^^^^^^^^ Expected a string literal
 
 Guppy compilation failed due to 1 previous error

tests/error/misc_errors/panic_tag_not_static.py

@@ -4,4 +4,4 @@
 
 @compile_guppy
 def foo(y: bool) -> None:
-    panic("foo" + "bar", y)
+    panic("foo" if y else "bar", y)

tests/error/misc_errors/result_tag_not_static.err

@@ -1,8 +1,8 @@
 Error: Expected a string literal (at $FILE:7:11)
   | 
 5 | @compile_guppy
-6 | def foo(y: bool) -> None:
-7 |     result("foo" + "bar", y)
-  |            ^^^^^^^^^^^^^ Expected a string literal
+6 | def foo(y: bool, x: int) -> None:
+7 |     result("foo" if y else "bar", x)
+  |            ^^^^^^^^^^^^^^^^^^^^^ Expected a string literal
 
 Guppy compilation failed due to 1 previous error

tests/error/misc_errors/result_tag_not_static.py

@@ -3,5 +3,5 @@
 
 
 @compile_guppy
-def foo(y: bool) -> None:
-    result("foo" + "bar", y)
+def foo(y: bool, x: int) -> None:
+    result("foo" if y else "bar", x)

tests/error/misc_errors/result_tag_not_str.err

@@ -1,8 +1,8 @@
-Error: Expected a string literal (at $FILE:7:11)
+Error: Type mismatch (at $FILE:7:11)
   | 
 5 | @compile_guppy
 6 | def foo(x: int) -> None:
 7 |     result((), x)
-  |            ^^ Expected a string literal
+  |            ^^ Expected expression of type `str`, got `()`
 
 Guppy compilation failed due to 1 previous error

tests/integration/test_panic.py

@@ -36,3 +36,10 @@ def baz() -> None:
         return panic("I panicked!")
 
     validate(module.compile())
+
+def test_py_message(validate):
+    @compile_guppy
+    def main(x: int) -> None:
+        panic(py("I" + "panicked" + "!"))
+
+    validate(main)

tests/integration/test_result.py

@@ -45,3 +45,10 @@ def main(x: int, y: float, z: bool) -> None:
         result("foo", z)
 
     validate(main)
+
+def test_py_tag(validate):
+    @compile_guppy
+    def main(x: int) -> None:
+        result(py("a" + "b"), x)
+
+    validate(main)