Emit zeroed() for libc structs without default (#84)

Author: lucic71

cpp2rust/converter/converter.cpp

@@ -5,6 +5,7 @@
 
 #include <clang/AST/APValue.h>
 #include <clang/AST/ParentMapContext.h>
+#include <clang/Basic/SourceManager.h>
 #include <llvm/ADT/DenseMap.h>
 #include <llvm/Support/ConvertUTF.h>
 
@@ -3090,6 +3091,12 @@ std::string Converter::GetDefaultAsStringFallback(clang::QualType qual_type) {
     return std::move(buf).str();
   }
 
+  if (auto record = qual_type->getAsRecordDecl()) {
+    if (ctx_.getSourceManager().isInSystemHeader(record->getLocation())) {
+      return std::format("std::mem::zeroed::<{}>()", ToString(qual_type));
+    }
+  }
+
   return std::format("<{}>::default()", ToString(qual_type));
 }
 

tests/unit/libc_struct_without_default.c

@@ -0,0 +1,33 @@
+// no-compile: refcount
+#include <assert.h>
+#include <netinet/in.h>
+#include <poll.h>
+#include <sys/stat.h>
+#include <time.h>
+
+int main() {
+  struct pollfd p;
+  p.fd = -1;
+  p.events = 0;
+  p.revents = 2;
+  assert(p.fd == -1);
+  assert(p.events == 0);
+  assert(p.revents == 2);
+
+  struct in_addr ia;
+  ia.s_addr = 1;
+  assert(ia.s_addr == 1);
+
+  struct tm t;
+  t.tm_year = 124;
+  t.tm_mon = 5;
+  t.tm_mday = 15;
+  assert(t.tm_year == 124);
+  assert(t.tm_mon == 5);
+  assert(t.tm_mday == 15);
+
+  struct stat st;
+  st.st_size = 1024;
+  assert(st.st_size == 1024);
+  return 0;
+}

tests/unit/out/unsafe/libc_struct_without_default.rs

@@ -0,0 +1,36 @@
+extern crate libc;
+use libc::*;
+extern crate libcc2rs;
+use libcc2rs::*;
+use std::collections::BTreeMap;
+use std::io::{Read, Seek, Write};
+use std::os::fd::{AsFd, FromRawFd, IntoRawFd};
+use std::rc::Rc;
+pub fn main() {
+    unsafe {
+        std::process::exit(main_0() as i32);
+    }
+}
+unsafe fn main_0() -> i32 {
+    let mut p: pollfd = std::mem::zeroed::<pollfd>();
+    p.fd = -1_i32;
+    p.events = 0_i16;
+    p.revents = 2_i16;
+    assert!(((((p.fd) == (-1_i32)) as i32) != 0));
+    assert!(((((p.events as i32) == (0)) as i32) != 0));
+    assert!(((((p.revents as i32) == (2)) as i32) != 0));
+    let mut ia: in_addr = std::mem::zeroed::<in_addr>();
+    ia.s_addr = 1_u32;
+    assert!(((((ia.s_addr) == (1_u32)) as i32) != 0));
+    let mut t: tm = std::mem::zeroed::<tm>();
+    t.tm_year = 124;
+    t.tm_mon = 5;
+    t.tm_mday = 15;
+    assert!(((((t.tm_year) == (124)) as i32) != 0));
+    assert!(((((t.tm_mon) == (5)) as i32) != 0));
+    assert!(((((t.tm_mday) == (15)) as i32) != 0));
+    let mut st: stat = std::mem::zeroed::<stat>();
+    st.st_size = 1024_i64;
+    assert!(((((st.st_size) == (1024_i64)) as i32) != 0));
+    return 0;
+}