[LLDB] Fix the handling of unnamed bit-fields when parsing DWARF

We ran into an assert when debugging clang and performing an expression on a class derived from DeclContext. The assert was indicating we were getting the offsets wrong for RecordDeclBitfields. We were getting both the size and offset of unnamed bit-field members wrong. We could fix this case with a quick change but as I extended the test suite to include more combinations we kept finding more cases that were being handled incorrectly. A fix that handled all the new cases as well as the cases already covered required a refactor of the existing technique.

Differential Revision: https://reviews.llvm.org/D72953

(cherry picked from commit fcaf5f6c01a09f23b948afb8c91c4dd951d4525e)

1 files changed, 81 insertions, 0 deletions

diff --git a/lldb/packages/Python/lldbsuite/test/lang/cpp/bitfields/main.cpp b/lldb/packages/Python/lldbsuite/test/lang/cpp/bitfields/main.cpp
new file mode 100644
index 00000000000..975c0f05683
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/lang/cpp/bitfields/main.cpp
@@ -0,0 +1,81 @@
+#include <stdint.h>
+
+int main(int argc, char const *argv[]) {
+  struct LargeBitsA {
+    unsigned int : 30, a : 20;
+  } lba;
+
+  struct LargeBitsB {
+    unsigned int a : 1, : 11, : 12, b : 20;
+  } lbb;
+
+  struct LargeBitsC {
+    unsigned int : 13, : 9, a : 1, b : 1, c : 5, d : 1, e : 20;
+  } lbc;
+
+  struct LargeBitsD {
+    char arr[3];
+    unsigned int : 30, a : 20;
+  } lbd;
+
+  // This case came up when debugging clang and models RecordDeclBits
+  struct BitExampleFromClangDeclContext {
+    class fields {
+      uint64_t : 13;
+      uint64_t : 9;
+
+      uint64_t a: 1;
+      uint64_t b: 1;
+      uint64_t c: 1;
+      uint64_t d: 1;
+      uint64_t e: 1;
+      uint64_t f: 1;
+      uint64_t g: 1;
+      uint64_t h: 1;
+      uint64_t i: 1;
+      uint64_t j: 1;
+      uint64_t k: 1;
+
+      // In order to reproduce the crash for this case we need the
+      // members of fields to stay private :-(
+      friend struct BitExampleFromClangDeclContext;
+    };
+
+    union {
+      struct fields f;
+    };
+
+    BitExampleFromClangDeclContext() {
+  f.a = 1;
+  f.b = 0;
+  f.c = 1;
+  f.d = 0;
+  f.e = 1;
+  f.f = 0;
+  f.g = 1;
+  f.h = 0;
+  f.i = 1;
+  f.j = 0;
+  f.k = 1;
+    } 
+  } clang_example;
+
+  lba.a = 2;
+
+  lbb.a = 1;
+  lbb.b = 3;
+
+  lbc.a = 1;
+  lbc.b = 0;
+  lbc.c = 4;
+  lbc.d = 1;
+  lbc.e = 20;
+
+  lbd.arr[0] = 'a';
+  lbd.arr[1] = 'b';
+  lbd.arr[2] = 'c';
+  lbd.a = 5;
+
+
+  return 0; // Set break point at this line.
+}