Add a new check to the readability module that flags uses of "magic numbers" (both floating-point and integral).

Patch by Florin Iucha <florin@signbit.net>

llvm-svn: 339516

1 files changed, 199 insertions, 0 deletions

diff --git a/clang-tools-extra/test/clang-tidy/readability-magic-numbers.cpp b/clang-tools-extra/test/clang-tidy/readability-magic-numbers.cpp
new file mode 100644
index 00000000000..3cf9dc52ea2
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/readability-magic-numbers.cpp
@@ -0,0 +1,199 @@
+// RUN: %check_clang_tidy %s readability-magic-numbers %t \
+// RUN: -config='{CheckOptions: \
+// RUN:  [{key: readability-magic-numbers.IgnoredIntegerValues, value: "0;1;2;10;100;"}, \
+// RUN:   {key: readability-magic-numbers.IgnoredFloatingPointValues, value: "3.14;2.71828;9.81;10000.0;101.0;0x1.2p3"}, \
+// RUN:   {key: readability-magic-numbers.IgnorePowersOf2IntegerValues, value: 1}]}' \
+// RUN: --
+
+template <typename T, int V>
+struct ValueBucket {
+  T value[V];
+};
+
+int BadGlobalInt = 5;
+// CHECK-MESSAGES: :[[@LINE-1]]:20: warning: 5 is a magic number; consider replacing it with a named constant [readability-magic-numbers]
+
+int IntSquarer(int param) {
+  return param * param;
+}
+
+void BuggyFunction() {
+  int BadLocalInt = 6;
+  // CHECK-MESSAGES: :[[@LINE-1]]:21: warning: 6 is a magic number; consider replacing it with a named constant [readability-magic-numbers]
+
+  (void)IntSquarer(7);
+  // CHECK-MESSAGES: :[[@LINE-1]]:20: warning: 7 is a magic number; consider replacing it with a named constant [readability-magic-numbers]
+
+  int LocalArray[15];
+  // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: 15 is a magic number; consider replacing it with a named constant [readability-magic-numbers]
+
+  for (int ii = 0; ii < 22; ++ii)
+  // CHECK-MESSAGES: :[[@LINE-1]]:25: warning: 22 is a magic number; consider replacing it with a named constant [readability-magic-numbers]
+  {
+    LocalArray[ii] = 3 * ii;
+    // CHECK-MESSAGES: :[[@LINE-1]]:22: warning: 3 is a magic number; consider replacing it with a named constant [readability-magic-numbers]
+  }
+
+  ValueBucket<int, 66> Bucket;
+  // CHECK-MESSAGES: :[[@LINE-1]]:20: warning: 66 is a magic number; consider replacing it with a named constant [readability-magic-numbers]
+}
+
+class TwoIntContainer {
+public:
+  TwoIntContainer(int val) : anotherMember(val * val), yetAnotherMember(6), anotherConstant(val + val) {}
+  // CHECK-MESSAGES: :[[@LINE-1]]:73: warning: 6 is a magic number; consider replacing it with a named constant [readability-magic-numbers]
+
+  int getValue() const;
+
+private:
+  int oneMember = 9;
+  // CHECK-MESSAGES: :[[@LINE-1]]:19: warning: 9 is a magic number; consider replacing it with a named constant [readability-magic-numbers]
+
+  int anotherMember;
+
+  int yetAnotherMember;
+
+  const int oneConstant = 2;
+
+  const int anotherConstant;
+};
+
+int ValueArray[] = {3, 5};
+// CHECK-MESSAGES: :[[@LINE-1]]:21: warning: 3 is a magic number; consider replacing it with a named constant [readability-magic-numbers]
+// CHECK-MESSAGES: :[[@LINE-2]]:24: warning: 5 is a magic number; consider replacing it with a named constant [readability-magic-numbers]
+
+float FloatPiVariable = 3.1415926535f;
+// CHECK-MESSAGES: :[[@LINE-1]]:25: warning: 3.1415926535f is a magic number; consider replacing it with a named constant [readability-magic-numbers]
+double DoublePiVariable = 6.283185307;
+// CHECK-MESSAGES: :[[@LINE-1]]:27: warning: 6.283185307 is a magic number; consider replacing it with a named constant [readability-magic-numbers]
+
+float SomeFloats[] = {0.5, 0x1.2p4};
+// CHECK-MESSAGES: :[[@LINE-1]]:23: warning: 0.5 is a magic number; consider replacing it with a named constant [readability-magic-numbers]
+// CHECK-MESSAGES: :[[@LINE-2]]:28: warning: 0x1.2p4 is a magic number; consider replacing it with a named constant [readability-magic-numbers]
+
+int getAnswer() {
+  if (ValueArray[0] < ValueArray[1])
+    return ValueArray[1];
+
+  return -3; // FILENOTFOUND
+  // CHECK-MESSAGES: :[[@LINE-1]]:11: warning: 3 is a magic number; consider replacing it with a named constant [readability-magic-numbers]
+}
+
+/*
+ * Clean code
+ */
+
+#define INT_MACRO 5
+
+const int GoodGlobalIntConstant = 42;
+
+constexpr int AlsoGoodGlobalIntConstant = 42;
+
+int InitializedByMacro = INT_MACRO;
+
+void SolidFunction() {
+  const int GoodLocalIntConstant = 43;
+
+  (void)IntSquarer(GoodLocalIntConstant);
+
+  int LocalArray[INT_MACRO];
+
+  ValueBucket<int, INT_MACRO> Bucket;
+}
+
+const int ConstValueArray[] = {7, 9};
+
+const int ConstValueArray2D[2][2] = {{7, 9}, {13, 15}};
+
+/*
+ * no warnings for ignored values (specified in the configuration above)
+ */
+int GrandfatheredIntegerValues[] = {0, 1, 2, 10, 100, -1, -10, -100, 65536};
+
+float GrandfatheredFloatValues[] = {3.14f, 3.14, 2.71828, 2.71828f, -1.01E2, 1E4, 0x1.2p3};
+
+/*
+ * no warnings for enums
+ */
+enum Smorgasbord {
+  STARTER,
+  ALPHA = 3,
+  BETA = 1 << 5,
+};
+
+const float FloatPiConstant = 3.1415926535f;
+const double DoublePiConstant = 6.283185307;
+
+const float Angles[] = {45.0f, 90.0f, 135.0f};
+
+double DoubleZeroIsAccepted = 0.0;
+float FloatZeroIsAccepted = 0.0f;
+
+namespace geometry {
+
+template <typename T>
+struct Point {
+  T x;
+  T y;
+
+  explicit Point(T xval, T yval) noexcept : x{xval}, y{yval} {
+  }
+};
+
+template <typename T>
+struct Dimension {
+  T x;
+  T y;
+
+  explicit Dimension(T xval, T yval) noexcept : x{xval}, y{yval} {
+  }
+};
+
+template <typename T>
+struct Rectangle {
+  Point<T> origin;
+  Dimension<T> size;
+  T rotation; // angle of rotation around origin
+
+  Rectangle(Point<T> origin_, Dimension<T> size_, T rotation_ = 0) noexcept : origin{origin_}, size{size_}, rotation{rotation_} {
+  }
+
+  bool contains(Point<T> point) const;
+};
+
+} // namespace geometry
+
+const geometry::Rectangle<double> mandelbrotCanvas{geometry::Point<double>{-2.5, -1}, geometry::Dimension<double>{3.5, 2}};
+
+// Simulate the macro magic in Google Test internal headers
+class AssertionHelper {
+public:
+  AssertionHelper(const char *Message, int LineNumber) : Message(Message), LineNumber(LineNumber) {}
+
+private:
+  const char *Message;
+  int LineNumber;
+};
+
+#define ASSERTION_HELPER_AT(M, L) AssertionHelper(M, L)
+
+#define ASSERTION_HELPER(M) ASSERTION_HELPER_AT(M, __LINE__)
+
+void FunctionWithCompilerDefinedSymbol(void) {
+  ASSERTION_HELPER("here and now");
+}
+
+// prove that integer literals introduced by the compiler are accepted silently
+extern int ConsumeString(const char *Input);
+
+const char *SomeStrings[] = {"alpha", "beta", "gamma"};
+
+int TestCheckerOverreach() {
+  int Total = 0;
+
+  for (const auto *Str : SomeStrings) {
+    Total += ConsumeString(Str);
+  }
+
+  return Total;
+}