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transpile: Various fixes to type handling for builtins #1860

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f317c23
transpile: Minor refactor to `convert_builtin`
Rua Jun 17, 2026
306a79c
transpile: Override `__builtin_object_size` call result type to `Size`
Rua Jun 17, 2026
c5e2c5b
transpile: Pass result type to `convert_builtin`
Rua Jun 17, 2026
c0915dc
transpile: Lift `Ok` out of `match` in `convert_builtin`
Rua Jun 17, 2026
04f75f7
transpile: Cast to expected type in `convert_builtin`
Rua Jun 18, 2026
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39 changes: 32 additions & 7 deletions c2rust-transpile/src/c_ast/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1306,17 +1306,18 @@ impl TypedAstContext {
}
}

/// Bubble types of unary and binary operators up from their args into the expression type.
///
/// In Clang 15 and below, the Clang AST resolves typedefs in the expression type of unary and
/// binary expressions. For example, a BinaryExpr node adding two `size_t` expressions will be
/// given an `unsigned long` type rather than the `size_t` typedef type. This behavior changed
/// in Clang 16. This method adjusts AST node types to match those produced by Clang 16 and
/// newer; on these later Clang versions, it should have no effect.
/// Overrides the result types of certain expressions to one of the `PULLBACK_KINDS` where
/// appropriate. Then bubbles those types up to the parent expressions.
///
/// This pass is necessary because we reify some typedef types (such as `size_t`) into their own
/// distinct Rust types. As such, we need to make sure we know the exact type to generate when
/// we translate an expr, not just its resolved type (looking through typedefs).
///
/// Additionally, in Clang 15 and below, the Clang AST resolves typedefs in the expression type
/// of unary and binary expressions. For example, a BinaryExpr node adding two `size_t`
/// expressions will be given an `unsigned long` type rather than the `size_t` typedef type.
/// This behavior changed in Clang 16. This method adjusts AST node types to match those
/// produced by Clang 16 and newer.
pub fn bubble_expr_types(&mut self) {
struct BubbleExprTypes<'a> {
ast_context: &'a mut TypedAstContext,
Expand Down Expand Up @@ -1379,6 +1380,30 @@ impl TypedAstContext {
self.ast_context,
self.ast_context.c_exprs[&e].kind.get_qual_type().unwrap(),
),
CExprKind::Call(result_type_id, callee_id, _) => {
let CExprKind::ImplicitCast(_, callee_id, CastKind::BuiltinFnToFnPtr, _, _) =
self.ast_context.index_unwrap_parens(callee_id).kind
else {
return;
};
let CExprKind::DeclRef(_, decl_id, _) =
self.ast_context.index_unwrap_parens(callee_id).kind
else {
return;
};
let CDeclKind::Function { ref name, .. } = self.ast_context[decl_id].kind
else {
return;
};

match name.as_str() {
"__builtin_object_size" => {
let type_id = self.ast_context.type_for_kind(&CTypeKind::Size);
Some(result_type_id.with_ctype(type_id))
}
_ => None,
}
}
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CExprKind::Paren(_ty, e) => self.ast_context.c_exprs[&e].kind.get_qual_type(),
CExprKind::UnaryType(_, op, _, _) => {
// All of these `CUnTypeOp`s should return `size_t`.
Expand Down
418 changes: 220 additions & 198 deletions c2rust-transpile/src/translator/builtins.rs
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2 changes: 1 addition & 1 deletion c2rust-transpile/src/translator/functions.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -393,7 +393,7 @@ impl<'c> Translation<'c> {

// Builtin function call
CExprKind::ImplicitCast(_, fexp, CastKind::BuiltinFnToFnPtr, _, _) => {
return self.convert_builtin(ctx, fexp, args);
return self.convert_builtin(ctx, override_ty, call_expr_ty, fexp, args);
}

// Function pointer call
Expand Down
12 changes: 6 additions & 6 deletions c2rust-transpile/tests/snapshots/snapshots__transpile@f128.c.2021.linux.clang15.snap
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Original file line number Diff line number Diff line change
Expand Up @@ -24,12 +24,12 @@ pub unsafe extern "C" fn long_double_test() {
let mut cast_from_float: ::f128::f128 = ::f128::f128::new(f);
let mut is_inf: bool = if huge.is_infinite() {
if huge.is_sign_positive() {
1
1 as ::core::ffi::c_int
} else {
-1
-1 as ::core::ffi::c_int
}
} else {
0
0 as ::core::ffi::c_int
} != 0;
if one != ::f128::f128::ZERO {
let mut dummy: ::core::ffi::c_int = 0;
Expand All @@ -48,12 +48,12 @@ pub unsafe extern "C" fn float128_test() {
let mut ld_from_float128: ::f128::f128 = one;
let mut is_inf: bool = if huge.is_infinite() {
if huge.is_sign_positive() {
1
1 as ::core::ffi::c_int
} else {
-1
-1 as ::core::ffi::c_int
}
} else {
0
0 as ::core::ffi::c_int
} != 0;
if one != ::f128::f128::ZERO {
let mut dummy: ::core::ffi::c_int = 0;
Expand Down
16 changes: 12 additions & 4 deletions c2rust-transpile/tests/snapshots/snapshots__transpile@f128.c.2024.linux.clang15.snap
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Original file line number Diff line number Diff line change
Expand Up @@ -24,9 +24,13 @@ pub unsafe extern "C" fn long_double_test() {
let mut cast_from_int: ::f128::f128 = ::f128::f128::new(i);
let mut cast_from_float: ::f128::f128 = ::f128::f128::new(f);
let mut is_inf: bool = if huge.is_infinite() {
if huge.is_sign_positive() { 1 } else { -1 }
if huge.is_sign_positive() {
1 as ::core::ffi::c_int
} else {
-1 as ::core::ffi::c_int
}
} else {
0
0 as ::core::ffi::c_int
} != 0;
if one != ::f128::f128::ZERO {
let mut dummy: ::core::ffi::c_int = 0;
Expand All @@ -44,9 +48,13 @@ pub unsafe extern "C" fn float128_test() {
let mut cast_from_float: ::f128::f128 = ::f128::f128::new(f);
let mut ld_from_float128: ::f128::f128 = one;
let mut is_inf: bool = if huge.is_infinite() {
if huge.is_sign_positive() { 1 } else { -1 }
if huge.is_sign_positive() {
1 as ::core::ffi::c_int
} else {
-1 as ::core::ffi::c_int
}
} else {
0
0 as ::core::ffi::c_int
} != 0;
if one != ::f128::f128::ZERO {
let mut dummy: ::core::ffi::c_int = 0;
Expand Down
13 changes: 7 additions & 6 deletions c2rust-transpile/tests/snapshots/snapshots__transpile@macros.c.2021.clang15.snap
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Original file line number Diff line number Diff line change
Expand Up @@ -119,14 +119,14 @@ pub unsafe extern "C" fn local_muts() {
let mut str_concatenation_ptr: *const ::core::ffi::c_char = STR_CONCATENATION.as_ptr();
let mut str_concatenation: [::core::ffi::c_char; 18] = STR_CONCATENATION;
let mut builtin: ::core::ffi::c_int =
(LITERAL_INT as ::core::ffi::c_uint).leading_zeros() as i32;
(LITERAL_INT as ::core::ffi::c_uint).leading_zeros() as ::core::ffi::c_int;
let mut ref_indexing: *const ::core::ffi::c_char = REF_MACRO;
let mut ref_struct: *const S = REF_LITERAL;
let mut ternary: ::core::ffi::c_int = TERNARY;
let mut member: ::core::ffi::c_int = MEMBER;
let mut stmt_expr: ::core::ffi::c_float = ({
let mut builtin_0: ::core::ffi::c_int =
(LITERAL_INT as ::core::ffi::c_uint).leading_zeros() as i32;
(LITERAL_INT as ::core::ffi::c_uint).leading_zeros() as ::core::ffi::c_int;
let mut indexing_0: ::core::ffi::c_char = INDEXING;
let mut mixed: ::core::ffi::c_float = MIXED_ARITHMETIC as ::core::ffi::c_float;
let mut i: ::core::ffi::c_int = 0 as ::core::ffi::c_int;
Expand Down Expand Up @@ -166,14 +166,15 @@ pub unsafe extern "C" fn local_consts() {
let indexing: ::core::ffi::c_char = INDEXING;
let str_concatenation_ptr: *const ::core::ffi::c_char = STR_CONCATENATION.as_ptr();
let str_concatenation: [::core::ffi::c_char; 18] = STR_CONCATENATION;
let builtin: ::core::ffi::c_int = (LITERAL_INT as ::core::ffi::c_uint).leading_zeros() as i32;
let builtin: ::core::ffi::c_int =
(LITERAL_INT as ::core::ffi::c_uint).leading_zeros() as ::core::ffi::c_int;
let ref_indexing: *const ::core::ffi::c_char = REF_MACRO;
let ref_struct: *const S = REF_LITERAL;
let ternary: ::core::ffi::c_int = TERNARY;
let member: ::core::ffi::c_int = MEMBER;
let stmt_expr: ::core::ffi::c_float = ({
let mut builtin_0: ::core::ffi::c_int =
(LITERAL_INT as ::core::ffi::c_uint).leading_zeros() as i32;
(LITERAL_INT as ::core::ffi::c_uint).leading_zeros() as ::core::ffi::c_int;
let mut indexing_0: ::core::ffi::c_char = INDEXING;
let mut mixed: ::core::ffi::c_float = MIXED_ARITHMETIC as ::core::ffi::c_float;
let mut i: ::core::ffi::c_int = 0 as ::core::ffi::c_int;
Expand Down Expand Up @@ -219,7 +220,7 @@ static mut global_static_const_str_concatenation_ptr: *const ::core::ffi::c_char
STR_CONCATENATION.as_ptr();
static mut global_static_const_str_concatenation: [::core::ffi::c_char; 18] = STR_CONCATENATION;
static mut global_static_const_builtin: ::core::ffi::c_int =
(LITERAL_INT as ::core::ffi::c_uint).leading_zeros() as i32;
(LITERAL_INT as ::core::ffi::c_uint).leading_zeros() as ::core::ffi::c_int;
static mut global_static_const_ref_indexing: *const ::core::ffi::c_char =
::core::ptr::null::<::core::ffi::c_char>();
static mut global_static_const_ref_struct: *const S = REF_LITERAL;
Expand Down Expand Up @@ -288,7 +289,7 @@ pub static mut global_const_str_concatenation_ptr: *const ::core::ffi::c_char =
pub static mut global_const_str_concatenation: [::core::ffi::c_char; 18] = STR_CONCATENATION;
#[no_mangle]
pub static mut global_const_builtin: ::core::ffi::c_int =
(LITERAL_INT as ::core::ffi::c_uint).leading_zeros() as i32;
(LITERAL_INT as ::core::ffi::c_uint).leading_zeros() as ::core::ffi::c_int;
#[no_mangle]
pub static mut global_const_ref_indexing: *const ::core::ffi::c_char =
::core::ptr::null::<::core::ffi::c_char>();
Expand Down
13 changes: 7 additions & 6 deletions c2rust-transpile/tests/snapshots/snapshots__transpile@macros.c.2024.clang15.snap
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Original file line number Diff line number Diff line change
Expand Up @@ -119,14 +119,14 @@ pub unsafe extern "C" fn local_muts() {
let mut str_concatenation_ptr: *const ::core::ffi::c_char = STR_CONCATENATION.as_ptr();
let mut str_concatenation: [::core::ffi::c_char; 18] = STR_CONCATENATION;
let mut builtin: ::core::ffi::c_int =
(LITERAL_INT as ::core::ffi::c_uint).leading_zeros() as i32;
(LITERAL_INT as ::core::ffi::c_uint).leading_zeros() as ::core::ffi::c_int;
let mut ref_indexing: *const ::core::ffi::c_char = REF_MACRO;
let mut ref_struct: *const S = REF_LITERAL;
let mut ternary: ::core::ffi::c_int = TERNARY;
let mut member: ::core::ffi::c_int = MEMBER;
let mut stmt_expr: ::core::ffi::c_float = ({
let mut builtin_0: ::core::ffi::c_int =
(LITERAL_INT as ::core::ffi::c_uint).leading_zeros() as i32;
(LITERAL_INT as ::core::ffi::c_uint).leading_zeros() as ::core::ffi::c_int;
let mut indexing_0: ::core::ffi::c_char = INDEXING;
let mut mixed: ::core::ffi::c_float = MIXED_ARITHMETIC as ::core::ffi::c_float;
let mut i: ::core::ffi::c_int = 0 as ::core::ffi::c_int;
Expand Down Expand Up @@ -166,14 +166,15 @@ pub unsafe extern "C" fn local_consts() {
let indexing: ::core::ffi::c_char = INDEXING;
let str_concatenation_ptr: *const ::core::ffi::c_char = STR_CONCATENATION.as_ptr();
let str_concatenation: [::core::ffi::c_char; 18] = STR_CONCATENATION;
let builtin: ::core::ffi::c_int = (LITERAL_INT as ::core::ffi::c_uint).leading_zeros() as i32;
let builtin: ::core::ffi::c_int =
(LITERAL_INT as ::core::ffi::c_uint).leading_zeros() as ::core::ffi::c_int;
let ref_indexing: *const ::core::ffi::c_char = REF_MACRO;
let ref_struct: *const S = REF_LITERAL;
let ternary: ::core::ffi::c_int = TERNARY;
let member: ::core::ffi::c_int = MEMBER;
let stmt_expr: ::core::ffi::c_float = ({
let mut builtin_0: ::core::ffi::c_int =
(LITERAL_INT as ::core::ffi::c_uint).leading_zeros() as i32;
(LITERAL_INT as ::core::ffi::c_uint).leading_zeros() as ::core::ffi::c_int;
let mut indexing_0: ::core::ffi::c_char = INDEXING;
let mut mixed: ::core::ffi::c_float = MIXED_ARITHMETIC as ::core::ffi::c_float;
let mut i: ::core::ffi::c_int = 0 as ::core::ffi::c_int;
Expand Down Expand Up @@ -219,7 +220,7 @@ static mut global_static_const_str_concatenation_ptr: *const ::core::ffi::c_char
STR_CONCATENATION.as_ptr();
static mut global_static_const_str_concatenation: [::core::ffi::c_char; 18] = STR_CONCATENATION;
static mut global_static_const_builtin: ::core::ffi::c_int =
(LITERAL_INT as ::core::ffi::c_uint).leading_zeros() as i32;
(LITERAL_INT as ::core::ffi::c_uint).leading_zeros() as ::core::ffi::c_int;
static mut global_static_const_ref_indexing: *const ::core::ffi::c_char =
::core::ptr::null::<::core::ffi::c_char>();
static mut global_static_const_ref_struct: *const S = REF_LITERAL;
Expand Down Expand Up @@ -288,7 +289,7 @@ pub static mut global_const_str_concatenation_ptr: *const ::core::ffi::c_char =
pub static mut global_const_str_concatenation: [::core::ffi::c_char; 18] = STR_CONCATENATION;
#[unsafe(no_mangle)]
pub static mut global_const_builtin: ::core::ffi::c_int =
(LITERAL_INT as ::core::ffi::c_uint).leading_zeros() as i32;
(LITERAL_INT as ::core::ffi::c_uint).leading_zeros() as ::core::ffi::c_int;
#[unsafe(no_mangle)]
pub static mut global_const_ref_indexing: *const ::core::ffi::c_char =
::core::ptr::null::<::core::ffi::c_char>();
Expand Down
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