Implement semantic analysis for transparent unions. This is largely
based on a patch from Anders Johnsen. CodeGen support is incomplete,
in that we do not properly coerce to the first field's type.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@70419 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/Sema/transparent-union.c b/test/Sema/transparent-union.c
new file mode 100644
index 0000000..90ecaad
--- /dev/null
+++ b/test/Sema/transparent-union.c
@@ -0,0 +1,40 @@
+// RUN: clang -fsyntax-only -Xclang -verify %s
+typedef union {
+ int *ip;
+ float *fp;
+} TU __attribute__((transparent_union));
+
+void f(TU);
+
+void g(int *ip, float *fp, char *cp) {
+ f(ip);
+ f(fp);
+ f(cp); // expected-error{{incompatible type}}
+ f(0);
+
+ TU tu_ip = ip; // expected-error{{incompatible type}}
+ TU tu;
+ tu.ip = ip;
+}
+
+/* FIXME: we'd like to just use an "int" here and align it differently
+ from the normal "int", but if we do so we lose the alignment
+ information from the typedef within the compiler. */
+typedef struct { int x, y; } __attribute__((aligned(8))) aligned_struct8;
+
+typedef struct { int x, y; } __attribute__((aligned(4))) aligned_struct4;
+typedef union {
+ aligned_struct4 s4; // expected-note{{alignment of first field}}
+ aligned_struct8 s8; // expected-warning{{alignment of field}}
+} TU1 __attribute__((transparent_union));
+
+typedef union {
+ char c; // expected-note{{size of first field is 8 bits}}
+ int i; // expected-warning{{size of field}}
+} TU2 __attribute__((transparent_union));
+
+typedef union {
+ float f; // expected-warning{{floating}}
+} TU3 __attribute__((transparent_union));
+
+typedef union { } TU4 __attribute__((transparent_union)); // expected-warning{{field}}