Auto merge of #122456 - maurer:cfi-nonpassed, r=workingjubilee

CFI: Skip non-passed arguments

Rust will occasionally rely on fn((), X) -> Y being compatible with fn(X) -> Y, since () is a non-passed argument. Relax CFI by choosing not to encode non-passed arguments.

This PR was split off from #121962 as part of fixing the larger vtable compatibility issues.

r? `@workingjubilee`

6 files changed, 65 insertions, 39 deletions

diff --git a/compiler/rustc_symbol_mangling/src/typeid/typeid_itanium_cxx_abi.rs b/compiler/rustc_symbol_mangling/src/typeid/typeid_itanium_cxx_abi.rs
index 51e2c96120c..76a5d942c66 100644
--- a/compiler/rustc_symbol_mangling/src/typeid/typeid_itanium_cxx_abi.rs
+++ b/compiler/rustc_symbol_mangling/src/typeid/typeid_itanium_cxx_abi.rs
@@ -18,7 +18,7 @@ use rustc_middle::ty::{
 use rustc_middle::ty::{GenericArg, GenericArgKind, GenericArgsRef};
 use rustc_span::def_id::DefId;
 use rustc_span::sym;
-use rustc_target::abi::call::{Conv, FnAbi};
+use rustc_target::abi::call::{Conv, FnAbi, PassMode};
 use rustc_target::abi::Integer;
 use rustc_target::spec::abi::Abi;
 use std::fmt::Write as _;
@@ -1040,19 +1040,27 @@ pub fn typeid_for_fnabi<'tcx>(
     typeid.push_str(&encode_ty(tcx, ty, &mut dict, encode_ty_options));
 
     // Encode the parameter types
+
+    // We erase ZSTs as we go if the argument is skipped. This is an implementation detail of how
+    // MIR is currently treated by rustc, and subject to change in the future. Specifically, MIR
+    // interpretation today will allow skipped arguments to simply not be passed at a call-site.
     if !fn_abi.c_variadic {
-        if !fn_abi.args.is_empty() {
-            for arg in fn_abi.args.iter() {
-                let ty = transform_ty(tcx, arg.layout.ty, transform_ty_options);
-                typeid.push_str(&encode_ty(tcx, ty, &mut dict, encode_ty_options));
-            }
-        } else {
+        let mut pushed_arg = false;
+        for arg in fn_abi.args.iter().filter(|arg| arg.mode != PassMode::Ignore) {
+            pushed_arg = true;
+            let ty = transform_ty(tcx, arg.layout.ty, transform_ty_options);
+            typeid.push_str(&encode_ty(tcx, ty, &mut dict, encode_ty_options));
+        }
+        if !pushed_arg {
             // Empty parameter lists, whether declared as () or conventionally as (void), are
             // encoded with a void parameter specifier "v".
             typeid.push('v');
         }
     } else {
         for n in 0..fn_abi.fixed_count as usize {
+            if fn_abi.args[n].mode == PassMode::Ignore {
+                continue;
+            }
             let ty = transform_ty(tcx, fn_abi.args[n].layout.ty, transform_ty_options);
             typeid.push_str(&encode_ty(tcx, ty, &mut dict, encode_ty_options));
         }
diff --git a/tests/codegen/sanitizer/cfi/emit-type-metadata-id-itanium-cxx-abi-paths.rs b/tests/codegen/sanitizer/cfi/emit-type-metadata-id-itanium-cxx-abi-paths.rs
index c5d8e0f22a2..ca781a99296 100644
--- a/tests/codegen/sanitizer/cfi/emit-type-metadata-id-itanium-cxx-abi-paths.rs
+++ b/tests/codegen/sanitizer/cfi/emit-type-metadata-id-itanium-cxx-abi-paths.rs
@@ -47,40 +47,42 @@ pub fn foo() where
     let _: Type4 = <Foo>::bar;
 }
 
-pub fn foo1(_: Type1) { }
+// Force arguments to be passed by using a reference. Otherwise, they may end up PassMode::Ignore
+
+pub fn foo1(_: &Type1) { }
 // CHECK: define{{.*}}4foo1{{.*}}!type ![[TYPE1:[0-9]+]] !type !{{[0-9]+}} !type !{{[0-9]+}} !type !{{[0-9]+}}
-pub fn foo2(_: Type1, _: Type1) { }
+pub fn foo2(_: &Type1, _: &Type1) { }
 // CHECK: define{{.*}}4foo2{{.*}}!type ![[TYPE2:[0-9]+]] !type !{{[0-9]+}} !type !{{[0-9]+}} !type !{{[0-9]+}}
-pub fn foo3(_: Type1, _: Type1, _: Type1) { }
+pub fn foo3(_: &Type1, _: &Type1, _: &Type1) { }
 // CHECK: define{{.*}}4foo3{{.*}}!type ![[TYPE3:[0-9]+]] !type !{{[0-9]+}} !type !{{[0-9]+}} !type !{{[0-9]+}}
-pub fn foo4(_: Type2) { }
+pub fn foo4(_: &Type2) { }
 // CHECK: define{{.*}}4foo4{{.*}}!type ![[TYPE4:[0-9]+]] !type !{{[0-9]+}} !type !{{[0-9]+}} !type !{{[0-9]+}}
-pub fn foo5(_: Type2, _: Type2) { }
+pub fn foo5(_: &Type2, _: &Type2) { }
 // CHECK: define{{.*}}4foo5{{.*}}!type ![[TYPE5:[0-9]+]] !type !{{[0-9]+}} !type !{{[0-9]+}} !type !{{[0-9]+}}
-pub fn foo6(_: Type2, _: Type2, _: Type2) { }
+pub fn foo6(_: &Type2, _: &Type2, _: &Type2) { }
 // CHECK: define{{.*}}4foo6{{.*}}!type ![[TYPE6:[0-9]+]] !type !{{[0-9]+}} !type !{{[0-9]+}} !type !{{[0-9]+}}
-pub fn foo7(_: Type3) { }
+pub fn foo7(_: &Type3) { }
 // CHECK: define{{.*}}4foo7{{.*}}!type ![[TYPE7:[0-9]+]] !type !{{[0-9]+}} !type !{{[0-9]+}} !type !{{[0-9]+}}
-pub fn foo8(_: Type3, _: Type3) { }
+pub fn foo8(_: &Type3, _: &Type3) { }
 // CHECK: define{{.*}}4foo8{{.*}}!type ![[TYPE8:[0-9]+]] !type !{{[0-9]+}} !type !{{[0-9]+}} !type !{{[0-9]+}}
-pub fn foo9(_: Type3, _: Type3, _: Type3) { }
+pub fn foo9(_: &Type3, _: &Type3, _: &Type3) { }
 // CHECK: define{{.*}}4foo9{{.*}}!type ![[TYPE9:[0-9]+]] !type !{{[0-9]+}} !type !{{[0-9]+}} !type !{{[0-9]+}}
-pub fn foo10(_: Type4) { }
+pub fn foo10(_: &Type4) { }
 // CHECK: define{{.*}}5foo10{{.*}}!type ![[TYPE10:[0-9]+]] !type !{{[0-9]+}} !type !{{[0-9]+}} !type !{{[0-9]+}}
-pub fn foo11(_: Type4, _: Type4) { }
+pub fn foo11(_: &Type4, _: &Type4) { }
 // CHECK: define{{.*}}5foo11{{.*}}!type ![[TYPE11:[0-9]+]] !type !{{[0-9]+}} !type !{{[0-9]+}} !type !{{[0-9]+}}
-pub fn foo12(_: Type4, _: Type4, _: Type4) { }
+pub fn foo12(_: &Type4, _: &Type4, _: &Type4) { }
 // CHECK: define{{.*}}5foo12{{.*}}!type ![[TYPE12:[0-9]+]] !type !{{[0-9]+}} !type !{{[0-9]+}} !type !{{[0-9]+}}
 
-// CHECK: ![[TYPE1]] = !{i64 0, !"_ZTSFvu{{[0-9]+}}NvNFNvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo10{{[{}][{}]}}extern{{[}][}]}}3barE"}
-// CHECK: ![[TYPE2]] = !{i64 0, !"_ZTSFvu{{[0-9]+}}NvNFNvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo10{{[{}][{}]}}extern{{[}][}]}}3barS_E"}
-// CHECK: ![[TYPE3]] = !{i64 0, !"_ZTSFvu{{[0-9]+}}NvNFNvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo10{{[{}][{}]}}extern{{[}][}]}}3barS_S_E"}
-// CHECK: ![[TYPE4]] = !{i64 0, !"_ZTSFvu{{[0-9]+}}NtNCNvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo11{{[{}][{}]}}closure{{[}][}]}}3FooE"}
-// CHECK: ![[TYPE5]] = !{i64 0, !"_ZTSFvu{{[0-9]+}}NtNCNvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo11{{[{}][{}]}}closure{{[}][}]}}3FooS_E"}
-// CHECK: ![[TYPE6]] = !{i64 0, !"_ZTSFvu{{[0-9]+}}NtNCNvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo11{{[{}][{}]}}closure{{[}][}]}}3FooS_S_E"}
-// CHECK: ![[TYPE7]] = !{i64 0, !"_ZTSFvu{{[0-9]+}}NtNkNvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo12{{[{}][{}]}}constant{{[}][}]}}3FooE"}
-// CHECK: ![[TYPE8]] = !{i64 0, !"_ZTSFvu{{[0-9]+}}NtNkNvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo12{{[{}][{}]}}constant{{[}][}]}}3FooS_E"}
-// CHECK: ![[TYPE9]] = !{i64 0, !"_ZTSFvu{{[0-9]+}}NtNkNvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo12{{[{}][{}]}}constant{{[}][}]}}3FooS_S_E"}
-// CHECK: ![[TYPE10]] = !{i64 0, !"_ZTSFvu{{[0-9]+}}NvNINvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo8{{[{}][{}]}}impl{{[}][}]}}3barE"}
-// CHECK: ![[TYPE11]] = !{i64 0, !"_ZTSFvu{{[0-9]+}}NvNINvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo8{{[{}][{}]}}impl{{[}][}]}}3barS_E"}
-// CHECK: ![[TYPE12]] = !{i64 0, !"_ZTSFvu{{[0-9]+}}NvNINvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo8{{[{}][{}]}}impl{{[}][}]}}3barS_S_E"}
+// CHECK: ![[TYPE1]] = !{i64 0, !"_ZTSFvu3refIu{{[0-9]+}}NvNFNvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo10{{[{}][{}]}}extern{{[}][}]}}3barEE"}
+// CHECK: ![[TYPE2]] = !{i64 0, !"_ZTSFvu3refIu{{[0-9]+}}NvNFNvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo10{{[{}][{}]}}extern{{[}][}]}}3barES0_E"}
+// CHECK: ![[TYPE3]] = !{i64 0, !"_ZTSFvu3refIu{{[0-9]+}}NvNFNvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo10{{[{}][{}]}}extern{{[}][}]}}3barES0_S0_E"}
+// CHECK: ![[TYPE4]] = !{i64 0, !"_ZTSFvu3refIu{{[0-9]+}}NtNCNvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo11{{[{}][{}]}}closure{{[}][}]}}3FooEE"}
+// CHECK: ![[TYPE5]] = !{i64 0, !"_ZTSFvu3refIu{{[0-9]+}}NtNCNvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo11{{[{}][{}]}}closure{{[}][}]}}3FooES0_E"}
+// CHECK: ![[TYPE6]] = !{i64 0, !"_ZTSFvu3refIu{{[0-9]+}}NtNCNvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo11{{[{}][{}]}}closure{{[}][}]}}3FooES0_S0_E"}
+// CHECK: ![[TYPE7]] = !{i64 0, !"_ZTSFvu3refIu{{[0-9]+}}NtNkNvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo12{{[{}][{}]}}constant{{[}][}]}}3FooEE"}
+// CHECK: ![[TYPE8]] = !{i64 0, !"_ZTSFvu3refIu{{[0-9]+}}NtNkNvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo12{{[{}][{}]}}constant{{[}][}]}}3FooES0_E"}
+// CHECK: ![[TYPE9]] = !{i64 0, !"_ZTSFvu3refIu{{[0-9]+}}NtNkNvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo12{{[{}][{}]}}constant{{[}][}]}}3FooES0_S0_E"}
+// CHECK: ![[TYPE10]] = !{i64 0, !"_ZTSFvu3refIu{{[0-9]+}}NvNINvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo8{{[{}][{}]}}impl{{[}][}]}}3barEE"}
+// CHECK: ![[TYPE11]] = !{i64 0, !"_ZTSFvu3refIu{{[0-9]+}}NvNINvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo8{{[{}][{}]}}impl{{[}][}]}}3barES0_E"}
+// CHECK: ![[TYPE12]] = !{i64 0, !"_ZTSFvu3refIu{{[0-9]+}}NvNINvC{{[[:print:]]+}}_{{[[:print:]]+}}3foo8{{[{}][{}]}}impl{{[}][}]}}3barES0_S0_E"}
diff --git a/tests/codegen/sanitizer/cfi/emit-type-metadata-id-itanium-cxx-abi-primitive-types.rs b/tests/codegen/sanitizer/cfi/emit-type-metadata-id-itanium-cxx-abi-primitive-types.rs
index 3a1a09150ea..38f507856bd 100644
--- a/tests/codegen/sanitizer/cfi/emit-type-metadata-id-itanium-cxx-abi-primitive-types.rs
+++ b/tests/codegen/sanitizer/cfi/emit-type-metadata-id-itanium-cxx-abi-primitive-types.rs
@@ -12,9 +12,9 @@ use core::ffi::*;
 pub fn foo1(_: ()) { }
 // CHECK: define{{.*}}4foo1{{.*}}!type ![[TYPE1:[0-9]+]] !type !{{[0-9]+}} !type !{{[0-9]+}} !type !{{[0-9]+}}
 pub fn foo2(_: (), _: c_void) { }
-// CHECK: define{{.*}}4foo2{{.*}}!type ![[TYPE2:[0-9]+]] !type !{{[0-9]+}} !type !{{[0-9]+}} !type !{{[0-9]+}}
+// CHECK: define{{.*}}4foo2{{.*}}!type ![[TYPE1:[0-9]+]] !type !{{[0-9]+}} !type !{{[0-9]+}} !type !{{[0-9]+}}
 pub fn foo3(_: (), _: c_void, _: c_void) { }
-// CHECK: define{{.*}}4foo3{{.*}}!type ![[TYPE3:[0-9]+]] !type !{{[0-9]+}} !type !{{[0-9]+}} !type !{{[0-9]+}}
+// CHECK: define{{.*}}4foo3{{.*}}!type ![[TYPE2:[0-9]+]] !type !{{[0-9]+}} !type !{{[0-9]+}} !type !{{[0-9]+}}
 pub fn foo4(_: *mut ()) { }
 // CHECK: define{{.*}}4foo4{{.*}}!type ![[TYPE4:[0-9]+]] !type !{{[0-9]+}} !type !{{[0-9]+}} !type !{{[0-9]+}}
 pub fn foo5(_: *mut (), _: *mut c_void) { }
@@ -131,8 +131,6 @@ pub fn foo60(_: &str, _: &str, _: &str) { }
 // CHECK: define{{.*}}5foo60{{.*}}!type ![[TYPE60:[0-9]+]] !type !{{[0-9]+}} !type !{{[0-9]+}} !type !{{[0-9]+}}
 
 // CHECK: ![[TYPE1]] = !{i64 0, !"_ZTSFvvE"}
-// CHECK: ![[TYPE2]] = !{i64 0, !"_ZTSFvvvE"}
-// CHECK: ![[TYPE3]] = !{i64 0, !"_ZTSFvvvvE"}
 // CHECK: ![[TYPE4]] = !{i64 0, !"_ZTSFvPvE"}
 // CHECK: ![[TYPE5]] = !{i64 0, !"_ZTSFvPvS_E"}
 // CHECK: ![[TYPE6]] = !{i64 0, !"_ZTSFvPvS_S_E"}
diff --git a/tests/codegen/sanitizer/cfi/emit-type-metadata-id-itanium-cxx-abi-repr-transparent-types.rs b/tests/codegen/sanitizer/cfi/emit-type-metadata-id-itanium-cxx-abi-repr-transparent-types.rs
index 0deda029c4b..6f47f5e3355 100644
--- a/tests/codegen/sanitizer/cfi/emit-type-metadata-id-itanium-cxx-abi-repr-transparent-types.rs
+++ b/tests/codegen/sanitizer/cfi/emit-type-metadata-id-itanium-cxx-abi-repr-transparent-types.rs
@@ -28,7 +28,7 @@ pub struct Type2<'a> {
     member3: &'a Type2<'a>,
 }
 
-pub struct Bar;
+pub struct Bar(i32);
 
 // repr(transparent) user-defined generic type
 #[repr(transparent)]
diff --git a/tests/codegen/sanitizer/cfi/normalize-integers.rs b/tests/codegen/sanitizer/cfi/normalize-integers.rs
index 210814eb9ae..801ed312be5 100644
--- a/tests/codegen/sanitizer/cfi/normalize-integers.rs
+++ b/tests/codegen/sanitizer/cfi/normalize-integers.rs
@@ -41,6 +41,6 @@ pub fn foo11(_: (), _: usize, _: usize, _: usize) { }
 // CHECK: ![[TYPE6]] = !{i64 0, !"_ZTSFv{{u3i16|u3i32|u3i64|u4i128}}E.normalized"}
 // CHECK: ![[TYPE7]] = !{i64 0, !"_ZTSFv{{u3i16|u3i32|u3i64|u4i128}}S_E.normalized"}
 // CHECK: ![[TYPE8]] = !{i64 0, !"_ZTSFv{{u3i16|u3i32|u3i64|u4i128}}S_S_E.normalized"}
-// CHECK: ![[TYPE9]] = !{i64 0, !"_ZTSFvv{{u3u16|u3u32|u3u64|u4u128}}E.normalized"}
-// CHECK: ![[TYPE10]] = !{i64 0, !"_ZTSFvv{{u3u16|u3u32|u3u64|u4u128}}S_E.normalized"}
-// CHECK: ![[TYPE11]] = !{i64 0, !"_ZTSFvv{{u3u16|u3u32|u3u64|u4u128}}S_S_E.normalized"}
+// CHECK: ![[TYPE9]] = !{i64 0, !"_ZTSFv{{u3u16|u3u32|u3u64|u4u128}}E.normalized"}
+// CHECK: ![[TYPE10]] = !{i64 0, !"_ZTSFv{{u3u16|u3u32|u3u64|u4u128}}S_E.normalized"}
+// CHECK: ![[TYPE11]] = !{i64 0, !"_ZTSFv{{u3u16|u3u32|u3u64|u4u128}}S_S_E.normalized"}
diff --git a/tests/ui/sanitizer/cfi-closure-fn-ptr-cast.rs b/tests/ui/sanitizer/cfi-closure-fn-ptr-cast.rs
new file mode 100644
index 00000000000..a46a3afd734
--- /dev/null
+++ b/tests/ui/sanitizer/cfi-closure-fn-ptr-cast.rs
@@ -0,0 +1,18 @@
+// Tests that converting a closure to a function pointer works
+// The notable thing being tested here is that when the closure does not capture anything,
+// the call method from its Fn trait takes a ZST representing its environment. The compiler then
+// uses the assumption that the ZST is non-passed to reify this into a function pointer.
+//
+// This checks that the reified function pointer will have the expected alias set at its call-site.
+
+//@ needs-sanitizer-cfi
+// FIXME(#122848) Remove only-linux once OSX CFI binaries work
+//@ only-linux
+//@ compile-flags: --crate-type=bin -Cprefer-dynamic=off -Clto -Zsanitizer=cfi
+//@ compile-flags: -C target-feature=-crt-static -C codegen-units=1 -C opt-level=0
+//@ run-pass
+
+pub fn main() {
+    let f: &fn() = &((|| ()) as _);
+    f();
+}