ImproperCTypes: re-separate linting and checking

no visible changes to rust users, just making the inner architecture of
the ImproperCTypes lints more sensible, with a clean separation between
the struct (now singular) that interacts with the linting system
and the struct (now singular) that visits the types to check FFI-safety

Author: niacdoial

compiler/rustc_lint/src/lib.rs

@@ -194,8 +194,7 @@ late_lint_methods!(
             DefaultCouldBeDerived: DefaultCouldBeDerived::default(),
             DerefIntoDynSupertrait: DerefIntoDynSupertrait,
             DropForgetUseless: DropForgetUseless,
-            ImproperCTypesDeclarations: ImproperCTypesDeclarations,
-            ImproperCTypesDefinitions: ImproperCTypesDefinitions,
+            ImproperCTypesLint: ImproperCTypesLint,
             InvalidFromUtf8: InvalidFromUtf8,
             VariantSizeDifferences: VariantSizeDifferences,
             PathStatements: PathStatements,

compiler/rustc_lint/src/types.rs

@@ -11,7 +11,7 @@ use tracing::debug;
 use {rustc_ast as ast, rustc_hir as hir};
 
 mod improper_ctypes; // these filed do the implementation for ImproperCTypesDefinitions,ImproperCTypesDeclarations
-pub(crate) use improper_ctypes::{ImproperCTypesDeclarations, ImproperCTypesDefinitions};
+pub(crate) use improper_ctypes::ImproperCTypesLint;
 
 use crate::lints::{
     AmbiguousWidePointerComparisons, AmbiguousWidePointerComparisonsAddrMetadataSuggestion,