Handle pattern types wrapped in Option in FFI checks

Author: oli-obk

compiler/rustc_lint/src/types.rs

@@ -861,6 +861,31 @@ fn ty_is_known_nonnull<'tcx>(
                 .filter_map(|variant| transparent_newtype_field(tcx, variant))
                 .any(|field| ty_is_known_nonnull(tcx, typing_env, field.ty(tcx, args), mode))
         }
+        ty::Pat(base, pat) => {
+            ty_is_known_nonnull(tcx, typing_env, *base, mode)
+                || match **pat {
+                    ty::PatternKind::Range { start, end, include_end } => match (start, end) {
+                        (Some(start), None) => {
+                            start.try_to_bits(tcx, typing_env).is_some_and(|i| i > 0)
+                        }
+                        (Some(start), Some(end)) => {
+                            if let Some(start) = start.try_to_bits(tcx, typing_env) {
+                                if let Some(end) = end.try_to_bits(tcx, typing_env) {
+                                    return if include_end {
+                                        // This also works for negative numbers, as we just need
+                                        // to ensure we aren't wrapping over zero.
+                                        start > 0 && end >= start
+                                    } else {
+                                        start > 0 && end > start
+                                    };
+                                }
+                            }
+                            false
+                        }
+                        _ => false,
+                    },
+                }
+        }
         _ => false,
     }
 }

tests/ui/lint/clashing-extern-fn.rs

@@ -499,13 +499,11 @@ mod pattern_types {
         extern "C" {
             fn pt_non_zero_usize() -> pattern_type!(usize is 1..);
             fn pt_non_zero_usize_opt() -> Option<pattern_type!(usize is 1..)>;
-            //~^ WARN not FFI-safe
             fn pt_non_zero_usize_opt_full_range() -> Option<pattern_type!(usize is 0..)>;
             //~^ WARN not FFI-safe
             fn pt_non_null_ptr() -> pattern_type!(usize is 1..);
             fn pt_non_zero_usize_wrapper() -> NonZeroUsize;
             fn pt_non_zero_usize_wrapper_opt() -> Option<NonZeroUsize>;
-            //~^ WARN not FFI-safe
         }
     }
     mod b {
@@ -515,12 +513,10 @@ mod pattern_types {
             // cases are warning for, from both a caller-convenience and optimisation perspective.
             fn pt_non_zero_usize() -> usize;
             fn pt_non_zero_usize_opt() -> usize;
-            //~^ WARN `pt_non_zero_usize_opt` redeclared with a different signature
             fn pt_non_null_ptr() -> *const ();
             //~^ WARN `pt_non_null_ptr` redeclared with a different signature
             fn pt_non_zero_usize_wrapper() -> usize;
             fn pt_non_zero_usize_wrapper_opt() -> usize;
-            //~^ WARN `pt_non_zero_usize_wrapper_opt` redeclared with a different signature
         }
     }
 }

tests/ui/lint/clashing-extern-fn.stderr

@@ -17,33 +17,15 @@ LL |             fn hidden_niche_unsafe_cell() -> Option<UnsafeCell<NonZero<usiz
    = help: consider adding a `#[repr(C)]`, `#[repr(transparent)]`, or integer `#[repr(...)]` attribute to this enum
    = note: enum has no representation hint
 
-warning: `extern` block uses type `Option<(usize) is 1..=>`, which is not FFI-safe
-  --> $DIR/clashing-extern-fn.rs:501:43
-   |
-LL |             fn pt_non_zero_usize_opt() -> Option<pattern_type!(usize is 1..)>;
-   |                                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
-   |
-   = help: consider adding a `#[repr(C)]`, `#[repr(transparent)]`, or integer `#[repr(...)]` attribute to this enum
-   = note: enum has no representation hint
-
 warning: `extern` block uses type `Option<(usize) is 0..=>`, which is not FFI-safe
-  --> $DIR/clashing-extern-fn.rs:503:54
+  --> $DIR/clashing-extern-fn.rs:502:54
    |
 LL |             fn pt_non_zero_usize_opt_full_range() -> Option<pattern_type!(usize is 0..)>;
    |                                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
    |
    = help: consider adding a `#[repr(C)]`, `#[repr(transparent)]`, or integer `#[repr(...)]` attribute to this enum
    = note: enum has no representation hint
 
-warning: `extern` block uses type `Option<NonZeroUsize>`, which is not FFI-safe
-  --> $DIR/clashing-extern-fn.rs:507:51
-   |
-LL |             fn pt_non_zero_usize_wrapper_opt() -> Option<NonZeroUsize>;
-   |                                                   ^^^^^^^^^^^^^^^^^^^^ not FFI-safe
-   |
-   = help: consider adding a `#[repr(C)]`, `#[repr(transparent)]`, or integer `#[repr(...)]` attribute to this enum
-   = note: enum has no representation hint
-
 warning: `clash` redeclared with a different signature
   --> $DIR/clashing-extern-fn.rs:13:13
    |
@@ -285,20 +267,8 @@ LL |             fn hidden_niche_unsafe_cell() -> Option<UnsafeCell<NonZero<usiz
    = note: expected `unsafe extern "C" fn() -> usize`
               found `unsafe extern "C" fn() -> Option<UnsafeCell<NonZero<usize>>>`
 
-warning: `pt_non_zero_usize_opt` redeclared with a different signature
-  --> $DIR/clashing-extern-fn.rs:517:13
-   |
-LL |             fn pt_non_zero_usize_opt() -> Option<pattern_type!(usize is 1..)>;
-   |             ------------------------------------------------------------------ `pt_non_zero_usize_opt` previously declared here
-...
-LL |             fn pt_non_zero_usize_opt() -> usize;
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ this signature doesn't match the previous declaration
-   |
-   = note: expected `unsafe extern "C" fn() -> Option<(usize) is 1..=>`
-              found `unsafe extern "C" fn() -> usize`
-
 warning: `pt_non_null_ptr` redeclared with a different signature
-  --> $DIR/clashing-extern-fn.rs:519:13
+  --> $DIR/clashing-extern-fn.rs:516:13
    |
 LL |             fn pt_non_null_ptr() -> pattern_type!(usize is 1..);
    |             ---------------------------------------------------- `pt_non_null_ptr` previously declared here
@@ -309,17 +279,5 @@ LL |             fn pt_non_null_ptr() -> *const ();
    = note: expected `unsafe extern "C" fn() -> (usize) is 1..=`
               found `unsafe extern "C" fn() -> *const ()`
 
-warning: `pt_non_zero_usize_wrapper_opt` redeclared with a different signature
-  --> $DIR/clashing-extern-fn.rs:522:13
-   |
-LL |             fn pt_non_zero_usize_wrapper_opt() -> Option<NonZeroUsize>;
-   |             ----------------------------------------------------------- `pt_non_zero_usize_wrapper_opt` previously declared here
-...
-LL |             fn pt_non_zero_usize_wrapper_opt() -> usize;
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ this signature doesn't match the previous declaration
-   |
-   = note: expected `unsafe extern "C" fn() -> Option<NonZeroUsize>`
-              found `unsafe extern "C" fn() -> usize`
-
-warning: 28 warnings emitted
+warning: 24 warnings emitted