[clang-tidy] Adding Fuchsia checker for virtual inheritance

Adds a check to the Fuchsia module to warn if classes are defined
with virtual inheritance.

See https://fuchsia.googlesource.com/zircon/+/master/docs/cxx.md for
reference.

Differential Revision: https://reviews.llvm.org/D40813

llvm-svn: 320841

1 files changed, 42 insertions, 0 deletions

diff --git a/clang-tools-extra/test/clang-tidy/fuchsia-virtual-inheritance.cpp b/clang-tools-extra/test/clang-tidy/fuchsia-virtual-inheritance.cpp
new file mode 100644
index 00000000000..0c3311afcbd
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/fuchsia-virtual-inheritance.cpp
@@ -0,0 +1,42 @@
+// RUN: %check_clang_tidy %s fuchsia-virtual-inheritance %t
+
+class A {
+public:
+  A(int value) : val(value) {}
+
+  int do_A() { return val; }
+
+private:
+  int val;
+};
+
+class B : public virtual A {
+  // CHECK-MESSAGES: [[@LINE-1]]:1: warning: direct virtual inheritance is disallowed [fuchsia-virtual-inheritance]
+  // CHECK-NEXT: class B : public virtual A {
+public:
+  B() : A(0) {}
+  int do_B() { return 1 + do_A(); }
+};
+
+class C : public virtual A {
+  // CHECK-MESSAGES: [[@LINE-1]]:1: warning: direct virtual inheritance is disallowed [fuchsia-virtual-inheritance]
+  // CHECK-NEXT: class C : public virtual A {
+public:
+  C() : A(0) {}
+  int do_C() { return 2 + do_A(); }
+};
+
+class D : public B, public C {
+public:
+  D(int value) : A(value), B(), C() {}
+
+  int do_D() { return do_A() + do_B() + do_C(); }
+};
+
+int main() {
+  A *a = new A(0);
+  B *b = new B();
+  C *c = new C();
+  D *d = new D(0);
+  return 0;
+}