[clang-tidy] Adding Fuchsia checker for statically constructed objects

Adds a check to the Fuchsia module to warn if statically-stored objects
are created, unless constructed with `constexpr`.

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

Differential Revision: https://reviews.llvm.org/D41546

llvm-svn: 322310

1 files changed, 91 insertions, 0 deletions

diff --git a/clang-tools-extra/test/clang-tidy/fuchsia-statically-constructed-objects.cpp b/clang-tools-extra/test/clang-tidy/fuchsia-statically-constructed-objects.cpp
new file mode 100644
index 00000000000..006494eeca6
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/fuchsia-statically-constructed-objects.cpp
@@ -0,0 +1,91 @@
+// RUN: %check_clang_tidy %s fuchsia-statically-constructed-objects %t
+
+// Trivial static is fine
+static int i;
+
+class ClassWithNoCtor {};
+
+class ClassWithCtor {
+public:
+  ClassWithCtor(int Val) : Val(Val) {}
+private:
+  int Val;
+};
+
+class ClassWithConstexpr {
+public:
+  ClassWithConstexpr(int Val1, int Val2) : Val(Val1) {}
+  constexpr ClassWithConstexpr(int Val) : Val(Val) {}
+
+private:
+  int Val;
+};
+
+ClassWithNoCtor A;
+ClassWithConstexpr C(0);
+ClassWithConstexpr E(0, 1);
+// CHECK-MESSAGES: [[@LINE-1]]:1: warning: static objects are disallowed; if possible, use a constexpr constructor instead [fuchsia-statically-constructed-objects]
+// CHECK-MESSAGES-NEXT:  ClassWithConstexpr E(0, 1);
+ClassWithCtor G(0);
+// CHECK-MESSAGES: [[@LINE-1]]:1: warning: static objects are disallowed; if possible, use a constexpr constructor instead [fuchsia-statically-constructed-objects]
+// CHECK-MESSAGES-NEXT:  ClassWithCtor G(0);
+
+static ClassWithNoCtor A2;
+static ClassWithConstexpr C2(0);
+static ClassWithConstexpr E2(0, 1);
+// CHECK-MESSAGES: [[@LINE-1]]:1: warning: static objects are disallowed; if possible, use a constexpr constructor instead [fuchsia-statically-constructed-objects]
+// CHECK-MESSAGES-NEXT:  static ClassWithConstexpr E2(0, 1);
+static ClassWithCtor G2(0);
+// CHECK-MESSAGES: [[@LINE-1]]:1: warning: static objects are disallowed; if possible, use a constexpr constructor instead [fuchsia-statically-constructed-objects]
+// CHECK-MESSAGES-NEXT:  static ClassWithCtor G2(0);
+
+struct StructWithConstexpr { constexpr StructWithConstexpr(int Val) {} };
+struct StructWithNoCtor {};
+struct StructWithCtor { StructWithCtor(); };
+
+StructWithNoCtor SNoCtor;
+StructWithConstexpr SConstexpr(0);
+StructWithCtor SCtor;
+// CHECK-MESSAGES: [[@LINE-1]]:1: warning: static objects are disallowed; if possible, use a constexpr constructor instead [fuchsia-statically-constructed-objects]
+// CHECK-MESSAGES-NEXT:  StructWithCtor SCtor;
+
+static StructWithConstexpr SConstexpr2(0);
+static StructWithNoCtor SNoCtor2;
+static StructWithCtor SCtor2;
+// CHECK-MESSAGES: [[@LINE-1]]:1: warning: static objects are disallowed; if possible, use a constexpr constructor instead [fuchsia-statically-constructed-objects]
+// CHECK-MESSAGES-NEXT:  static StructWithCtor SCtor2;
+
+extern StructWithCtor SCtor3;
+
+class ClassWithStaticMember {
+private:
+  static StructWithNoCtor S;
+};
+
+ClassWithStaticMember Z();
+
+class S {
+  int Val;
+public:
+  constexpr S(int i) : Val(100 / i) {}
+  int getVal() const { return Val; }
+};
+
+static S s1(1);
+static S s2(0); 
+// CHECK-MESSAGES: [[@LINE-1]]:1: warning: static objects are disallowed; if possible, use a constexpr constructor instead [fuchsia-statically-constructed-objects]
+// CHECK-MESSAGES-NEXT: static S s2(0);
+
+extern int get_i();
+static S s3(get_i());
+// CHECK-MESSAGES: [[@LINE-1]]:1: warning: static objects are disallowed; if possible, use a constexpr constructor instead [fuchsia-statically-constructed-objects]
+// CHECK-MESSAGES-NEXT:  static S s3(get_i());
+
+void f() {
+  // Locally static is fine
+  static int i;
+  static ClassWithNoCtor A2;
+  static ClassWithConstexpr C2(0);
+  static ClassWithConstexpr E2(0, 1);
+  static ClassWithCtor G2(0);
+}