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Narrow const macro DeclRef exclusion to only variables #1391

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Narrow const macro DeclRef exclusion to only variables #1391

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16 changes: 9 additions & 7 deletions c2rust-transpile/src/translator/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3338,13 +3338,15 @@ impl<'c> Translation<'c> {
.ok_or_else(|| format_err!("Missing declref {:?}", decl_id))?
.kind;
if ctx.is_const {
// TODO Determining which declarations have been declared within the scope of the const macro expr
// vs. which are out-of-scope of the const macro is non-trivial,
// so for now, we don't allow const macros referencing any declarations.
return Err(format_translation_err!(
self.ast_context.display_loc(src_loc),
"Cannot yet refer to declarations in a const expr",
));
if let CDeclKind::Variable { .. } = decl {
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I didn't do this initially because I wasn't sure about other declarations within a function and how that interacted with global scope, so I wanted to err on the safer side, since this is supposed to be temporary.

// TODO Determining which variables have been declared within the scope of the const macro expr
// vs. which are out-of-scope of the const macro is non-trivial,
// so for now, we don't allow const macros referencing any variables.
return Err(format_translation_err!(
self.ast_context.display_loc(src_loc),
"Cannot yet refer to variables in a const expr",
));
}

#[allow(unreachable_code)] // TODO temporary (see above).
if let CDeclKind::Variable {
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4 changes: 4 additions & 0 deletions c2rust-transpile/tests/snapshots/macros.c
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Expand Up @@ -405,3 +405,7 @@ unsigned int ntlm_v2_blob_len(struct ntlmdata *ntlm) { return NTLMv2_BLOB_LEN; }
int late_init_var() {
return LATE_INIT_VAR;
}

enum foo { Variant1, };
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How does this work if this is defined within a function, the macro is defined outside of it, and used within it?

#define VARIANT1 Variant1
enum foo fooval = VARIANT1;
5 changes: 5 additions & 0 deletions c2rust-transpile/tests/snapshots/[email protected]
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Expand Up @@ -34,6 +34,8 @@ pub type zstd_platform_dependent_type = core::ffi::c_long;
pub struct ntlmdata {
pub target_info_len: core::ffi::c_uint,
}
pub type foo = core::ffi::c_uint;
pub const Variant1: foo = 0;
pub const UINTPTR_MAX: core::ffi::c_ulong = 18446744073709551615 as core::ffi::c_ulong;
pub const true_0: core::ffi::c_int = 1 as core::ffi::c_int;
pub const LITERAL_INT: core::ffi::c_int = 0xffff as core::ffi::c_int;
Expand Down Expand Up @@ -429,6 +431,9 @@ pub unsafe extern "C" fn late_init_var() -> core::ffi::c_int {
i
});
}
pub const VARIANT1: core::ffi::c_int = Variant1 as core::ffi::c_int;
#[no_mangle]
pub static mut fooval: foo = VARIANT1 as foo;
unsafe extern "C" fn run_static_initializers() {
global_static_const_ptr_arithmetic = PTR_ARITHMETIC;
global_static_const_indexing = NESTED_STR[LITERAL_FLOAT as core::ffi::c_int as usize];
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