Add a test for a struct from a C pointer

Author: certik

integration_tests/CMakeLists.txt

@@ -374,6 +374,7 @@ RUN(NAME bindc_04            LABELS llvm c NOFAST)
 RUN(NAME bindc_07            LABELS cpython llvm c NOFAST)
 RUN(NAME bindc_08            LABELS cpython llvm c)
 RUN(NAME bindc_09            LABELS cpython llvm c)
+RUN(NAME bindc_10            LABELS cpython llvm c)
 RUN(NAME exit_01             LABELS cpython llvm c NOFAST)
 RUN(NAME exit_02     FAIL    LABELS cpython llvm c NOFAST)
 RUN(NAME exit_03             LABELS cpython llvm c wasm wasm_x86 wasm_x64)

integration_tests/bindc_10.py

@@ -0,0 +1,32 @@
+from lpython import (i64, i16, CPtr, c_p_pointer, Pointer, sizeof, packed,
+        dataclass, ccallable, ccall, i32)
+
+@ccall
+def _lfortran_malloc(size: i32) -> CPtr:
+    pass
+
+
+def alloc(buf_size:i64) -> CPtr:
+    return _lfortran_malloc(i32(buf_size))
+
+
+@ccallable
+@packed
+@dataclass
+class S:
+    a: i16
+    b: i64
+
+
+def main():
+    p1: CPtr = alloc(sizeof(S))
+    print(p1)
+    p2: Pointer[S] = c_p_pointer(p1, S)
+    p2.a = i16(5)
+    p2.b = i64(4)
+    print(p2.a, p2.b)
+    assert p2.a == i16(5)
+    assert p2.b == i64(4)
+
+
+main()