Implementing C99 partial re-initialization behavior (DR-253)

Based on previous discussion on the mailing list, clang currently lacks support
for C99 partial re-initialization behavior:
Reference: http://lists.cs.uiuc.edu/pipermail/cfe-dev/2013-April/029188.html
Reference: http://www.open-std.org/jtc1/sc22/wg14/www/docs/dr_253.htm

This patch attempts to fix this problem.

Given the following code snippet,

struct P1 { char x[6]; };
struct LP1 { struct P1 p1; };

struct LP1 l = { .p1 = { "foo" }, .p1.x[2] = 'x' };
// this example is adapted from the example for "struct fred x[]" in DR-253;
// currently clang produces in l: { "\0\0x" },
//   whereas gcc 4.8 produces { "fox" };
// with this fix, clang will also produce: { "fox" };


Differential Review: http://reviews.llvm.org/D5789

llvm-svn: 239446

1 files changed, 41 insertions, 0 deletions

diff --git a/clang/test/Analysis/designated-initializer.c b/clang/test/Analysis/designated-initializer.c
new file mode 100644
index 00000000000..b601f872571
--- /dev/null
+++ b/clang/test/Analysis/designated-initializer.c
@@ -0,0 +1,41 @@
+// RUN: %clang_cc1 -analyze -analyzer-checker=debug.DumpCFG %s 2>&1 \
+// RUN:   | FileCheck %s
+
+struct Q { int a, b, c; };
+union UQ { struct Q q; };
+union UQ getUQ() {
+  union UQ u = { { 1, 2, 3 } };
+  return u;
+}
+
+void test() {
+  struct LUQ { union UQ uq; } var = { getUQ(), .uq.q.a = 100 };
+  struct Q s[] = {
+    [0] = (struct Q){1, 2},
+    [0].c = 3
+  }; 
+}
+
+// CHECK: void test()
+// CHECK: [B1]
+// CHECK:   1: getUQ
+// CHECK:   2: [B1.1] (ImplicitCastExpr, FunctionToPointerDecay, union UQ (*)())
+// CHECK:   3: [B1.2]()
+// CHECK:   4: 100
+// CHECK:   5: /*no init*/
+// CHECK:   6: /*no init*/
+// CHECK:   7: {[B1.4], [B1.5], [B1.6]}
+// CHECK:   8: {[B1.7]}
+// CHECK:   9: {/*base*/[B1.3], /*updater*/[B1.8]}
+// CHECK:  10: {[B1.3], .uq.q.a = [B1.4]}
+// CHECK:  11: struct LUQ var = {getUQ(), .uq.q.a = 100};
+// CHECK:  12: 1
+// CHECK:  13: 2
+// CHECK:  14: /*implicit*/(int)0
+// CHECK:  15: {[B1.12], [B1.13]}
+// CHECK:  18: /*no init*/
+// CHECK:  19: /*no init*/
+// CHECK:  20: 3
+// CHECK:  21: {[B1.18], [B1.19], [B1.20]}
+// CHECK:  22: {/*base*/[B1.17], /*updater*/[B1.21]} 
+// CHECK:  24: struct Q s[] = {[0] = (struct Q){1, 2}, [0].c = 3};