Rearchitect -Wconversion and -Wsign-compare. Instead of computing them

"bottom-up" when implicit casts and comparisons are inserted, compute them
"top-down" when the full expression is finished.  Makes it easier to
coordinate warnings and thus implement -Wconversion for signedness
conversions without double-warning with -Wsign-compare.  Also makes it possible
to realize that a signedness conversion is okay because the context is
performing the inverse conversion.  Also simplifies some logic that was
trying to calculate the ultimate comparison/result type and getting it wrong.
Also fixes a problem with the C++ explicit casts which are often "implemented"
in the AST with a series of implicit cast expressions.

llvm-svn: 103174

1 files changed, 17 insertions, 0 deletions

diff --git a/clang/test/SemaCXX/conditional-expr.cpp b/clang/test/SemaCXX/conditional-expr.cpp
index a812a5920d6..f1fe8ba79bb 100644
--- a/clang/test/SemaCXX/conditional-expr.cpp
+++ b/clang/test/SemaCXX/conditional-expr.cpp
@@ -238,3 +238,20 @@ namespace PR6757 {
     (void)(true ? Bar() : Foo3()); // expected-error{{no viable constructor copying temporary}}
   }
 }
+
+// Reduced from selfhost.
+namespace test1 {
+  struct A {
+    enum Foo {
+      fa, fb, fc, fd, fe, ff
+    };
+
+    Foo x();
+  };
+
+  void foo(int);
+
+  void test(A *a) {
+    foo(a ? a->x() : 0);
+  }
+}