Add -Wdangling-else.

This works like described in  http://drdobbs.com/blogs/cpp/231602010
Fixes http://llvm.org/PR11609

llvm-svn: 147202

1 files changed, 55 insertions, 0 deletions

diff --git a/clang/test/Parser/warn-dangling-else.cpp b/clang/test/Parser/warn-dangling-else.cpp
new file mode 100644
index 00000000000..e91af9814ff
--- /dev/null
+++ b/clang/test/Parser/warn-dangling-else.cpp
@@ -0,0 +1,55 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -Wdangling-else %s
+
+void f(int a, int b, int c, int d, int e) {
+
+  // should warn
+  { if (a) if (b) d++; else e++; } // expected-warning {{add explicit braces to avoid dangling else}}
+  { if (a) while (b) if (c) d++; else e++; } // expected-warning {{add explicit braces to avoid dangling else}}
+  { if (a) switch (b) if (c) d++; else e++; } // expected-warning {{add explicit braces to avoid dangling else}}
+  { if (a) for (;;) if (c) d++; else e++; } // expected-warning {{add explicit braces to avoid dangling else}}
+  { if (a) if (b) if (d) d++; else e++; else d--; } // expected-warning {{add explicit braces to avoid dangling else}}
+
+  if (a)
+    if (b) {
+      d++;
+    } else e++; // expected-warning {{add explicit braces to avoid dangling else}}
+
+  // shouldn't
+  { if (a) if (b) d++; }
+  { if (a) if (b) if (c) d++; }
+  { if (a) if (b) d++; else e++; else d--; }
+  { if (a) if (b) if (d) d++; else e++; else d--; else e--; }
+  { if (a) do if (b) d++; else e++; while (c); }
+
+  if (a) {
+    if (b) d++;
+    else e++;
+  }
+
+  if (a) {
+    if (b) d++;
+  } else e++;
+}
+
+// Somewhat more elaborate case that shouldn't warn.
+class A {
+ public:
+  void operator<<(const char* s) {}
+};
+
+void HandleDisabledThing() {}
+A GetThing() { return A(); }
+
+#define FOO(X) \
+   switch (0) default: \
+     if (!(X)) \
+       HandleDisabledThing(); \
+     else \
+       GetThing()
+
+void f(bool cond) {
+  int x = 0;
+  if (cond)
+    FOO(x) << "hello"; // no warning
+}
+