Move fix suggestion to subdiagnostic (#19464)

Summary
--

This PR tweaks Ruff's internal usage of the new diagnostic model to more
closely
match the intended use, as I understand it. Specifically, it moves the
fix/help
suggestion from the primary annotation's message to a subdiagnostic. In
turn, it
adds the secondary/noqa code as the new primary annotation message. As
shown in
the new `ruff_db` tests, this more closely mirrors Ruff's current
diagnostic
output.

I also added `Severity::Help` to render the fix suggestion with a
`help:` prefix
instead of `info:`.

These changes don't have any external impact now but should help a bit
with #19415.

Test Plan
--

New full output format tests in `ruff_db`

Rendered Diagnostics
--

Full diagnostic output from `annotate-snippets` in this PR:

``` 
error[unused-import]: `os` imported but unused
  --> fib.py:1:8
   |
 1 | import os
   |        ^^
   |
 help: Remove unused import: `os`
```

Current Ruff output for the same code:

```
fib.py:1:8: F401 [*] `os` imported but unused
  |
1 | import os
  |        ^^ F401
  |
  = help: Remove unused import: `os`
```

Proposed final output after #19415:

``` 
F401 [*] `os` imported but unused
  --> fib.py:1:8
   |
 1 | import os
   |        ^^
   |
 help: Remove unused import: `os`
```

These are slightly updated from
https://github.com/astral-sh/ruff/pull/19464#issuecomment-3097377634
below to remove the extra noqa codes in the primary annotation messages
for the first and third cases.

crates/ty_python_semantic/src/types.rs

@@ -11,7 +11,7 @@ use diagnostic::{
     INVALID_CONTEXT_MANAGER, INVALID_SUPER_ARGUMENT, NOT_ITERABLE, POSSIBLY_UNBOUND_IMPLICIT_CALL,
     UNAVAILABLE_IMPLICIT_SUPER_ARGUMENTS,
 };
-use ruff_db::diagnostic::{Annotation, Diagnostic, Severity, Span, SubDiagnostic};
+use ruff_db::diagnostic::{Annotation, Diagnostic, Span, SubDiagnostic, SubDiagnosticSeverity};
 use ruff_db::files::File;
 use ruff_python_ast::name::Name;
 use ruff_python_ast::{self as ast, AnyNodeRef};
@@ -7077,7 +7077,7 @@ impl<'db> BoolError<'db> {
                     not_boolable_type.display(context.db())
                 ));
                 let mut sub = SubDiagnostic::new(
-                    Severity::Info,
+                    SubDiagnosticSeverity::Info,
                     "`__bool__` methods must only have a `self` parameter",
                 );
                 if let Some((func_span, parameter_span)) = not_boolable_type
@@ -7102,7 +7102,7 @@ impl<'db> BoolError<'db> {
                     not_boolable = not_boolable_type.display(context.db()),
                 ));
                 let mut sub = SubDiagnostic::new(
-                    Severity::Info,
+                    SubDiagnosticSeverity::Info,
                     format_args!(
                         "`{return_type}` is not assignable to `bool`",
                         return_type = return_type.display(context.db()),
@@ -7128,7 +7128,7 @@ impl<'db> BoolError<'db> {
                     not_boolable_type.display(context.db())
                 ));
                 let sub = SubDiagnostic::new(
-                    Severity::Info,
+                    SubDiagnosticSeverity::Info,
                     format_args!(
                         "`__bool__` on `{}` must be callable",
                         not_boolable_type.display(context.db())

crates/ty_python_semantic/src/types/call/bind.rs

@@ -30,7 +30,7 @@ use crate::types::{
     MethodWrapperKind, PropertyInstanceType, SpecialFormType, TypeMapping, UnionType,
     WrapperDescriptorKind, enums, ide_support, todo_type,
 };
-use ruff_db::diagnostic::{Annotation, Diagnostic, Severity, SubDiagnostic};
+use ruff_db::diagnostic::{Annotation, Diagnostic, SubDiagnostic, SubDiagnosticSeverity};
 use ruff_python_ast as ast;
 
 /// Binding information for a possible union of callables. At a call site, the arguments must be
@@ -1668,8 +1668,10 @@ impl<'db> CallableBinding<'db> {
                         .first()
                         .and_then(|overload| overload.spans(context.db()))
                     {
-                        let mut sub =
-                            SubDiagnostic::new(Severity::Info, "First overload defined here");
+                        let mut sub = SubDiagnostic::new(
+                            SubDiagnosticSeverity::Info,
+                            "First overload defined here",
+                        );
                         sub.annotate(Annotation::primary(spans.signature));
                         diag.sub(sub);
                     }
@@ -1696,7 +1698,7 @@ impl<'db> CallableBinding<'db> {
                         implementation.and_then(|function| function.spans(context.db()))
                     {
                         let mut sub = SubDiagnostic::new(
-                            Severity::Info,
+                            SubDiagnosticSeverity::Info,
                             "Overload implementation defined here",
                         );
                         sub.annotate(Annotation::primary(spans.signature));
@@ -2570,8 +2572,10 @@ impl<'db> BindingError<'db> {
                             overload.parameter_span(context.db(), Some(parameter.index))
                         })
                     {
-                        let mut sub =
-                            SubDiagnostic::new(Severity::Info, "Matching overload defined here");
+                        let mut sub = SubDiagnostic::new(
+                            SubDiagnosticSeverity::Info,
+                            "Matching overload defined here",
+                        );
                         sub.annotate(Annotation::primary(name_span));
                         sub.annotate(
                             Annotation::secondary(parameter_span)
@@ -2607,7 +2611,8 @@ impl<'db> BindingError<'db> {
                 } else if let Some((name_span, parameter_span)) =
                     callable_ty.parameter_span(context.db(), Some(parameter.index))
                 {
-                    let mut sub = SubDiagnostic::new(Severity::Info, "Function defined here");
+                    let mut sub =
+                        SubDiagnostic::new(SubDiagnosticSeverity::Info, "Function defined here");
                     sub.annotate(Annotation::primary(name_span));
                     sub.annotate(
                         Annotation::secondary(parameter_span).message("Parameter declared here"),
@@ -2733,7 +2738,10 @@ impl<'db> BindingError<'db> {
                     let module = parsed_module(context.db(), typevar_definition.file(context.db()))
                         .load(context.db());
                     let typevar_range = typevar_definition.full_range(context.db(), &module);
-                    let mut sub = SubDiagnostic::new(Severity::Info, "Type variable defined here");
+                    let mut sub = SubDiagnostic::new(
+                        SubDiagnosticSeverity::Info,
+                        "Type variable defined here",
+                    );
                     sub.annotate(Annotation::primary(typevar_range.into()));
                     diag.sub(sub);
                 }
@@ -2801,7 +2809,7 @@ impl UnionDiagnostic<'_, '_> {
     /// diagnostic.
     fn add_union_context(&self, db: &'_ dyn Db, diag: &mut Diagnostic) {
         let sub = SubDiagnostic::new(
-            Severity::Info,
+            SubDiagnosticSeverity::Info,
             format_args!(
                 "Union variant `{callable_ty}` is incompatible with this call site",
                 callable_ty = self.binding.callable_type.display(db),
@@ -2810,7 +2818,7 @@ impl UnionDiagnostic<'_, '_> {
         diag.sub(sub);
 
         let sub = SubDiagnostic::new(
-            Severity::Info,
+            SubDiagnosticSeverity::Info,
             format_args!(
                 "Attempted to call union type `{}`",
                 self.callable_type.display(db)

crates/ty_python_semantic/src/types/context.rs

@@ -1,7 +1,7 @@
 use std::fmt;
 
 use drop_bomb::DebugDropBomb;
-use ruff_db::diagnostic::{DiagnosticTag, SubDiagnostic};
+use ruff_db::diagnostic::{DiagnosticTag, SubDiagnostic, SubDiagnosticSeverity};
 use ruff_db::parsed::ParsedModuleRef;
 use ruff_db::{
     diagnostic::{Annotation, Diagnostic, DiagnosticId, IntoDiagnosticMessage, Severity, Span},
@@ -330,7 +330,7 @@ impl Drop for LintDiagnosticGuard<'_, '_> {
         let mut diag = self.diag.take().unwrap();
 
         diag.sub(SubDiagnostic::new(
-            Severity::Info,
+            SubDiagnosticSeverity::Info,
             match self.source {
                 LintSource::Default => format!("rule `{}` is enabled by default", diag.id()),
                 LintSource::Cli => format!("rule `{}` was selected on the command line", diag.id()),

crates/ty_python_semantic/src/types/diagnostic.rs

@@ -20,7 +20,7 @@ use crate::types::{SpecialFormType, Type, protocol_class::ProtocolClassLiteral};
 use crate::util::diagnostics::format_enumeration;
 use crate::{Db, FxIndexMap, Module, ModuleName, Program, declare_lint};
 use itertools::Itertools;
-use ruff_db::diagnostic::{Annotation, Diagnostic, Severity, SubDiagnostic};
+use ruff_db::diagnostic::{Annotation, Diagnostic, SubDiagnostic, SubDiagnosticSeverity};
 use ruff_python_ast::{self as ast, AnyNodeRef};
 use ruff_text_size::{Ranged, TextRange};
 use rustc_hash::FxHashSet;
@@ -1929,7 +1929,7 @@ pub(super) fn report_implicit_return_type(
         ));
 
         let mut sub_diagnostic = SubDiagnostic::new(
-            Severity::Info,
+            SubDiagnosticSeverity::Info,
             "Only classes that directly inherit from `typing.Protocol` \
             or `typing_extensions.Protocol` are considered protocol classes",
         );
@@ -2037,7 +2037,7 @@ pub(crate) fn report_instance_layout_conflict(
     ));
 
     let mut subdiagnostic = SubDiagnostic::new(
-        Severity::Info,
+        SubDiagnosticSeverity::Info,
         "Two classes cannot coexist in a class's MRO if their instances \
         have incompatible memory layouts",
     );
@@ -2230,7 +2230,7 @@ pub(crate) fn report_bad_argument_to_get_protocol_members(
     diagnostic.info("Only protocol classes can be passed to `get_protocol_members`");
 
     let mut class_def_diagnostic = SubDiagnostic::new(
-        Severity::Info,
+        SubDiagnosticSeverity::Info,
         format_args!(
             "`{}` is declared here, but it is not a protocol class:",
             class.name(db)
@@ -2292,7 +2292,7 @@ pub(crate) fn report_runtime_check_against_non_runtime_checkable_protocol(
     diagnostic.set_primary_message("This call will raise `TypeError` at runtime");
 
     let mut class_def_diagnostic = SubDiagnostic::new(
-        Severity::Info,
+        SubDiagnosticSeverity::Info,
         format_args!(
             "`{class_name}` is declared as a protocol class, \
                 but it is not declared as runtime-checkable"
@@ -2326,7 +2326,7 @@ pub(crate) fn report_attempted_protocol_instantiation(
     diagnostic.set_primary_message("This call will raise `TypeError` at runtime");
 
     let mut class_def_diagnostic = SubDiagnostic::new(
-        Severity::Info,
+        SubDiagnosticSeverity::Info,
         format_args!("Protocol classes cannot be instantiated"),
     );
     class_def_diagnostic.annotate(
@@ -2360,7 +2360,7 @@ pub(crate) fn report_duplicate_bases(
         builder.into_diagnostic(format_args!("Duplicate base class `{duplicate_name}`",));
 
     let mut sub_diagnostic = SubDiagnostic::new(
-        Severity::Info,
+        SubDiagnosticSeverity::Info,
         format_args!(
             "The definition of class `{}` will raise `TypeError` at runtime",
             class.name(db)

crates/ty_python_semantic/src/util/diagnostics.rs

@@ -1,5 +1,5 @@
 use crate::{Db, Program, PythonVersionWithSource};
-use ruff_db::diagnostic::{Annotation, Diagnostic, Severity, SubDiagnostic};
+use ruff_db::diagnostic::{Annotation, Diagnostic, SubDiagnostic, SubDiagnosticSeverity};
 use std::fmt::Write;
 
 /// Add a subdiagnostic to `diagnostic` that explains why a certain Python version was inferred.
@@ -23,7 +23,7 @@ pub fn add_inferred_python_version_hint_to_diagnostic(
         crate::PythonVersionSource::ConfigFile(source) => {
             if let Some(span) = source.span(db) {
                 let mut sub_diagnostic = SubDiagnostic::new(
-                    Severity::Info,
+                    SubDiagnosticSeverity::Info,
                     format_args!("Python {version} was assumed when {action}"),
                 );
                 sub_diagnostic.annotate(Annotation::primary(span).message(format_args!(
@@ -39,7 +39,7 @@ pub fn add_inferred_python_version_hint_to_diagnostic(
         crate::PythonVersionSource::PyvenvCfgFile(source) => {
             if let Some(span) = source.span(db) {
                 let mut sub_diagnostic = SubDiagnostic::new(
-                    Severity::Info,
+                    SubDiagnosticSeverity::Info,
                     format_args!(
                         "Python {version} was assumed when {action} because of your virtual environment"
                     ),