Warn if deprecated function is referred (#1011)

Summary:
This diff implements the last missing feature for deprecation warnings (#376): to warn when the deprecated function is referred (e.g. passed as function reference).

The implementation checks when typechecking an expression, whether the type of an expression is a deprecated function/bound method. If that's the case, a deprecated warning is generated.

If we only add this check, we might run into the issue that a deprecated function call would generate 2 deprecation warnings, one when the function is typechecked, and another when the call is typechecked.

To avoid the duplication, we avoid emitting the deprecation warning when typechecking a function call, instead we emit the deprecation warning when generating the call target.

As a consequence, the error message of deprecation warning is changed from "Calling" a deprecated function to "Reference to" a deprecated function. Suggestions are welcome for how to improve clarify of this error message.

Pull Request resolved: #1011

Test Plan:
Imported from GitHub, without a `Test Plan:` line.

Rollback Plan:

Reviewed By: rchen152

Differential Revision: D81681196

Pulled By: yangdanny97

fbshipit-source-id: 8d106589c7ce85cf8daa3c0f5992401edb448531

Author: fangyi-zhou

conformance/third_party/conformance.exp

@@ -3973,14 +3973,24 @@
     },
     {
       "code": -2,
-      "column": 23,
-      "concise_description": "Call to deprecated function `_directives_deprecated_library.norwegian_blue`",
-      "description": "Call to deprecated function `_directives_deprecated_library.norwegian_blue`",
+      "column": 1,
+      "concise_description": "`_directives_deprecated_library.norwegian_blue` is deprecated",
+      "description": "`_directives_deprecated_library.norwegian_blue` is deprecated",
       "line": 24,
       "name": "deprecated",
-      "stop_column": 26,
+      "stop_column": 23,
       "stop_line": 24
     },
+    {
+      "code": -2,
+      "column": 5,
+      "concise_description": "`_directives_deprecated_library.norwegian_blue` is deprecated",
+      "description": "`_directives_deprecated_library.norwegian_blue` is deprecated",
+      "line": 25,
+      "name": "deprecated",
+      "stop_column": 27,
+      "stop_line": 25
+    },
     {
       "code": -2,
       "column": 12,
@@ -3995,7 +4005,7 @@
       "code": -2,
       "column": 5,
       "concise_description": "`+` is not supported between `Spam` and `Literal[1]`",
-      "description": "`+` is not supported between `Spam` and `Literal[1]`\n  Call to deprecated function `_directives_deprecated_library.Spam.__add__`",
+      "description": "`+` is not supported between `Spam` and `Literal[1]`\n  `_directives_deprecated_library.Spam.__add__` is deprecated",
       "line": 41,
       "name": "unsupported-operation",
       "stop_column": 13,
@@ -4005,7 +4015,7 @@
       "code": -2,
       "column": 1,
       "concise_description": "`+=` is not supported between `Spam` and `Literal[1]`",
-      "description": "`+=` is not supported between `Spam` and `Literal[1]`\n  Call to deprecated function `_directives_deprecated_library.Spam.__add__`",
+      "description": "`+=` is not supported between `Spam` and `Literal[1]`\n  `_directives_deprecated_library.Spam.__add__` is deprecated",
       "line": 42,
       "name": "unsupported-operation",
       "stop_column": 10,
@@ -4014,8 +4024,8 @@
     {
       "code": -2,
       "column": 1,
-      "concise_description": "Call to deprecated function `_directives_deprecated_library.Spam.greasy`",
-      "description": "Call to deprecated function `_directives_deprecated_library.Spam.greasy`",
+      "concise_description": "`_directives_deprecated_library.Spam.greasy` is deprecated",
+      "description": "`_directives_deprecated_library.Spam.greasy` is deprecated",
       "line": 44,
       "name": "deprecated",
       "stop_column": 12,
@@ -4024,8 +4034,8 @@
     {
       "code": -2,
       "column": 1,
-      "concise_description": "Call to deprecated function `_directives_deprecated_library.Spam.shape`",
-      "description": "Call to deprecated function `_directives_deprecated_library.Spam.shape`",
+      "concise_description": "`_directives_deprecated_library.Spam.shape` is deprecated",
+      "description": "`_directives_deprecated_library.Spam.shape` is deprecated",
       "line": 47,
       "name": "deprecated",
       "stop_column": 11,
@@ -4034,41 +4044,41 @@
     {
       "code": -2,
       "column": 1,
-      "concise_description": "Call to deprecated function `_directives_deprecated_library.Spam.shape`",
-      "description": "Call to deprecated function `_directives_deprecated_library.Spam.shape`",
+      "concise_description": "`_directives_deprecated_library.Spam.shape` is deprecated",
+      "description": "`_directives_deprecated_library.Spam.shape` is deprecated",
       "line": 48,
       "name": "deprecated",
       "stop_column": 11,
       "stop_line": 48
     },
     {
       "code": -2,
-      "column": 10,
-      "concise_description": "Call to deprecated function `Invocable.__call__`",
-      "description": "Call to deprecated function `Invocable.__call__`",
+      "column": 1,
+      "concise_description": "`Invocable.__call__` is deprecated",
+      "description": "`Invocable.__call__` is deprecated",
       "line": 58,
       "name": "deprecated",
-      "stop_column": 12,
+      "stop_column": 10,
       "stop_line": 58
     },
     {
       "code": -2,
-      "column": 6,
-      "concise_description": "Call to deprecated function `lorem`",
-      "description": "Call to deprecated function `lorem`",
+      "column": 1,
+      "concise_description": "`lorem` is deprecated",
+      "description": "`lorem` is deprecated",
       "line": 69,
       "name": "deprecated",
-      "stop_column": 8,
+      "stop_column": 6,
       "stop_line": 69
     },
     {
       "code": -2,
-      "column": 10,
-      "concise_description": "Call to deprecated function `SupportsFoo1.foo`",
-      "description": "Call to deprecated function `SupportsFoo1.foo`",
+      "column": 5,
+      "concise_description": "`SupportsFoo1.foo` is deprecated",
+      "description": "`SupportsFoo1.foo` is deprecated",
       "line": 98,
       "name": "deprecated",
-      "stop_column": 12,
+      "stop_column": 10,
       "stop_line": 98
     }
   ],

conformance/third_party/conformance.result

@@ -138,9 +138,7 @@
   "dataclasses_usage.py": [],
   "directives_assert_type.py": [],
   "directives_cast.py": [],
-  "directives_deprecated.py": [
-    "Line 25: Expected 1 errors"
-  ],
+  "directives_deprecated.py": [],
   "directives_no_type_check.py": [],
   "directives_reveal_type.py": [],
   "directives_type_checking.py": [],

conformance/third_party/results.json

@@ -1,9 +1,9 @@
 {
   "total": 138,
-  "pass": 87,
-  "fail": 51,
-  "pass_rate": 0.63,
-  "differences": 233,
+  "pass": 88,
+  "fail": 50,
+  "pass_rate": 0.64,
+  "differences": 232,
   "passing": [
     "aliases_explicit.py",
     "aliases_newtype.py",
@@ -34,6 +34,7 @@
     "dataclasses_usage.py",
     "directives_assert_type.py",
     "directives_cast.py",
+    "directives_deprecated.py",
     "directives_no_type_check.py",
     "directives_reveal_type.py",
     "directives_type_checking.py",
@@ -107,7 +108,6 @@
     "constructors_callable.py": 9,
     "dataclasses_final.py": 1,
     "dataclasses_slots.py": 2,
-    "directives_deprecated.py": 1,
     "enums_members.py": 3,
     "exceptions_context_managers.py": 2,
     "generics_base_class.py": 1,

pyrefly/lib/alt/call.rs

@@ -249,7 +249,23 @@ impl<'a, Ans: LookupAnswer> AnswersSolver<'a, Ans> {
         context: Option<&dyn Fn() -> ErrorContext>,
     ) -> CallTarget {
         match self.as_call_target(ty.clone()) {
-            Some(target) => target,
+            Some(target) => {
+                let metadata = target.function_metadata();
+                if let Some(m) = metadata
+                    && m.flags.is_deprecated
+                {
+                    self.error(
+                        errors,
+                        range,
+                        ErrorInfo::new(ErrorKind::Deprecated, context),
+                        format!(
+                            "`{}` is deprecated",
+                            m.kind.as_func_id().format(self.module().name())
+                        ),
+                    );
+                }
+                target
+            }
             None => {
                 let expect_message = match call_style {
                     CallStyle::Method(method) => {
@@ -566,19 +582,6 @@ impl<'a, Ans: LookupAnswer> AnswersSolver<'a, Ans> {
         ctor_targs: Option<&mut TArgs>,
     ) -> Type {
         let metadata = call_target.function_metadata();
-        if let Some(m) = metadata
-            && m.flags.is_deprecated
-        {
-            self.error(
-                errors,
-                range,
-                ErrorInfo::new(ErrorKind::Deprecated, context),
-                format!(
-                    "Call to deprecated function `{}`",
-                    m.kind.as_func_id().format(self.module().name())
-                ),
-            );
-        }
         // Does this call target correspond to a function whose keyword arguments we should save?
         let kw_metadata = {
             if let Some(m) = metadata

pyrefly/lib/alt/expr.rs

@@ -215,6 +215,34 @@ impl<'a, Ans: LookupAnswer> AnswersSolver<'a, Ans> {
             .into_ty()
     }
 
+    /// Check whether a type corresponds to a deprecated function or method, and if so, log a deprecation warning.
+    pub fn check_for_deprecated_call(&self, ty: &Type, range: TextRange, errors: &ErrorCollector) {
+        let deprecated_function = match ty {
+            Type::Function(f) if f.metadata.flags.is_deprecated => {
+                Some(f.metadata.kind.as_func_id().format(self.module().name()))
+            }
+            Type::BoundMethod(m) if m.func.metadata().flags.is_deprecated => Some(
+                m.func
+                    .metadata()
+                    .kind
+                    .as_func_id()
+                    .format(self.module().name()),
+            ),
+            Type::Overload(o) if o.metadata.flags.is_deprecated => {
+                Some(o.metadata.kind.as_func_id().format(self.module().name()))
+            }
+            _ => None,
+        };
+        if let Some(deprecated_function) = deprecated_function {
+            self.error(
+                errors,
+                range,
+                ErrorInfo::Kind(ErrorKind::Deprecated),
+                format!("`{}` is deprecated", deprecated_function),
+            );
+        }
+    }
+
     /// Like expr_infer_with_hint(), but returns a TypeInfo that includes narrowing information.
     pub fn expr_infer_type_info_with_hint(
         &self,
@@ -264,6 +292,8 @@ impl<'a, Ans: LookupAnswer> AnswersSolver<'a, Ans> {
             // at the end.
             _ => TypeInfo::of_ty(self.expr_infer_type_no_trace(x, hint, errors)),
         };
+        // Check for deprecation
+        self.check_for_deprecated_call(res.ty(), x.range(), errors);
         self.record_type_trace(x.range(), res.ty());
         res
     }

pyrefly/lib/test/calls.rs

@@ -90,7 +90,20 @@ testcase!(
 from warnings import deprecated
 @deprecated("function is deprecated")
 def old_function() -> None: ...
-old_function()  # E: Call to deprecated function `old_function`
+old_function()  # E: `old_function` is deprecated
+    "#,
+);
+
+testcase!(
+    test_deprecated_function_reference,
+    r#"
+from typing import Callable
+from warnings import deprecated
+@deprecated("function is deprecated")
+def old_function() -> None: ...
+
+def take_callable(f: Callable) -> None: ...
+take_callable(old_function)  # E: `old_function` is deprecated
     "#,
 );
 
@@ -103,7 +116,7 @@ class C:
     def old_function(self) -> None: ...
 
 c = C()
-c.old_function()  # E: Call to deprecated function `C.old_function`
+c.old_function()  # E: `C.old_function` is deprecated
     "#,
 );
 
@@ -121,7 +134,7 @@ def f(x: str) -> str: ...
 def f(x: int | str) -> int | str:
     return x
 
-f(0)  # E: Call to deprecated function `f`
+f(0)  # E: `f` is deprecated
     "#,
 );
 

pyrefly/lib/test/imports.rs

@@ -861,7 +861,7 @@ testcase!(
     r#"
 from foo import x # E: `x` is deprecated
 
-x()  # E: Call to deprecated function `foo.x`
+x()  # E: `foo.x` is deprecated
 "#,
 );
 
@@ -871,7 +871,7 @@ testcase!(
     r#"
 from foo import x as y # E: `x` is deprecated
 
-y()  # E: Call to deprecated function `foo.x`
+y()  # E: `foo.x` is deprecated
 "#,
 );
 
@@ -881,7 +881,7 @@ testcase!(
     r#"
 from foo import * # E: `x` is deprecated
 
-x()  # E: Call to deprecated function `foo.x`
+x()  # E: `foo.x` is deprecated
 "#,
 );
 
@@ -923,7 +923,7 @@ testcase!(
     r#"
 from foo import x # E: `x` is deprecated
 
-x()  # E: Call to deprecated function `foo.x`
+x()  # E: `foo.x` is deprecated
 "#,
 );
 

test/errors.md

@@ -23,6 +23,10 @@ $ echo "x: str = 12" > $TMPDIR/shown1.py && \
 > echo "import shown1; y: int = shown1.x" > $TMPDIR/shown2.py && \
 > $PYREFLY check --python-version 3.13.0 $TMPDIR/shown2.py --check-all --output-format=min-text
 */shown*.py:1:* (glob)
+ WARN ast.pyi:1102:10-11: `Constant.n` is deprecated [deprecated]
+ WARN ast.pyi:1102:10-18: `Constant.n` is deprecated [deprecated]
+ WARN ast.pyi:1107:10-11: `Constant.s` is deprecated [deprecated]
+ WARN ast.pyi:1107:10-18: `Constant.s` is deprecated [deprecated]
  WARN importlib/_bootstrap_external.pyi:1:40-41: `WindowsRegistryFinder` is deprecated [deprecated]
 */shown*.py:1:* (glob)
 [1]