[clang-tidy] Add readability-simplify-boolean-expr check to clang-tidy

This check looks for comparisons between boolean expressions and boolean
constants and simplifies them to just use the appropriate boolean expression
directly.

if (b == true) becomes if (b)
if (b == false) becomes if (!b)
if (b && true) becomes if (b)
if (b && false) becomes if (false)
if (b || true) becomes if (true)
if (b || false) becomes if (b)
e ? true : false becomes e
e ? false : true becomes !e
if (true) t(); else f(); becomes t();
if (false) t(); else f(); becomes f();
if (e) return true; else return false; becomes return (e);
if (e) return false; else return true; becomes return !(e);
if (e) b = true; else b = false; becomes b = e;
if (e) b = false; else b = true; becomes b = !(e);

http://reviews.llvm.org/D7648

Patch by Richard Thomson!

llvm-svn: 234626

1 files changed, 543 insertions, 0 deletions

diff --git a/clang-tools-extra/test/clang-tidy/readability-simplify-bool-expr.cpp b/clang-tools-extra/test/clang-tidy/readability-simplify-bool-expr.cpp
new file mode 100644
index 00000000000..0658a17b278
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/readability-simplify-bool-expr.cpp
@@ -0,0 +1,543 @@
+// RUN: $(dirname %s)/check_clang_tidy.sh %s readability-simplify-boolean-expr %t
+// REQUIRES: shell
+
+bool a1 = false;
+
+//=-=-=-=-=-=-= operator ==
+bool aa = false == a1;
+// CHECK-MESSAGES: :[[@LINE-1]]:11: warning: redundant boolean literal supplied to boolean operator [readability-simplify-boolean-expr]
+// CHECK-FIXES: {{^bool aa = !a1;$}}
+bool ab = true == a1;
+// CHECK-MESSAGES: :[[@LINE-1]]:11: warning: {{.*}} to boolean operator
+// CHECK-FIXES: {{^bool ab = a1;$}}
+bool a2 = a1 == false;
+// CHECK-MESSAGES: :[[@LINE-1]]:17: warning: {{.*}} to boolean operator
+// CHECK-FIXES: {{^bool a2 = !a1;$}}
+bool a3 = a1 == true;
+// CHECK-MESSAGES: :[[@LINE-1]]:17: warning: {{.*}} to boolean operator
+// CHECK-FIXES: {{^bool a3 = a1;$}}
+
+//=-=-=-=-=-=-= operator !=
+bool n1 = a1 != false;
+// CHECK-MESSAGES: :[[@LINE-1]]:17: warning: {{.*}} to boolean operator
+// CHECK-FIXES: {{^bool n1 = a1;$}}
+bool n2 = a1 != true;
+// CHECK-MESSAGES: :[[@LINE-1]]:17: warning: {{.*}} to boolean operator
+// CHECK-FIXES: {{^bool n2 = !a1;$}}
+bool n3 = false != a1;
+// CHECK-MESSAGES: :[[@LINE-1]]:11: warning: {{.*}} to boolean operator
+// CHECK-FIXES: {{^bool n3 = a1;$}}
+bool n4 = true != a1;
+// CHECK-MESSAGES: :[[@LINE-1]]:11: warning: {{.*}} to boolean operator
+// CHECK-FIXES: {{^bool n4 = !a1;$}}
+
+//=-=-=-=-=-=-= operator ||
+bool a4 = a1 || false;
+// CHECK-MESSAGES: :[[@LINE-1]]:17: warning: {{.*}} to boolean operator
+// CHECK-FIXES: {{^bool a4 = a1;$}}
+bool a5 = a1 || true;
+// CHECK-MESSAGES: :[[@LINE-1]]:17: warning: {{.*}} to boolean operator
+// CHECK-FIXES: {{^bool a5 = true;$}}
+bool a6 = false || a1;
+// CHECK-MESSAGES: :[[@LINE-1]]:11: warning: {{.*}} to boolean operator
+// CHECK-FIXES: {{^bool a6 = a1;$}}
+bool a7 = true || a1;
+// CHECK-MESSAGES: :[[@LINE-1]]:11: warning: {{.*}} to boolean operator
+// CHECK-FIXES: {{^bool a7 = true;$}}
+
+//=-=-=-=-=-=-= operator &&
+bool a8 = a1 && false;
+// CHECK-MESSAGES: :[[@LINE-1]]:17: warning: {{.*}} to boolean operator
+// CHECK-FIXES: {{^bool a8 = false;$}}
+bool a9 = a1 && true;
+// CHECK-MESSAGES: :[[@LINE-1]]:17: warning: {{.*}} to boolean operator
+// CHECK-FIXES: {{^bool a9 = a1;$}}
+bool ac = false && a1;
+// CHECK-MESSAGES: :[[@LINE-1]]:11: warning: {{.*}} to boolean operator
+// CHECK-FIXES: {{^bool ac = false;$}}
+bool ad = true && a1;
+// CHECK-MESSAGES: :[[@LINE-1]]:11: warning: {{.*}} to boolean operator
+// CHECK-FIXES: {{^bool ad = a1;$}}
+
+void if_with_bool_literal_condition() {
+  int i = 0;
+  if (false) {
+    i = 1;
+  } else {
+    i = 2;
+  }
+  i = 3;
+  // CHECK-MESSAGES: :[[@LINE-6]]:7: warning: {{.*}} in if statement condition
+  // CHECK-FIXES:      {{^  int i = 0;$}}
+  // CHECK-FIXES-NEXT: {{^  {$}}
+  // CHECK-FIXES-NEXT: {{^    i = 2;$}}
+  // CHECK-FIXES-NEXT: {{^  }$}}
+  // CHECK-FIXES-NEXT: {{^  i = 3;$}}
+
+  i = 4;
+  if (true) {
+    i = 5;
+  } else {
+    i = 6;
+  }
+  i = 7;
+  // CHECK-MESSAGES: :[[@LINE-6]]:7: warning: {{.*}} in if statement condition
+  // CHECK-FIXES:      {{^  i = 4;$}}
+  // CHECK-FIXES-NEXT: {{^  {$}}
+  // CHECK-FIXES-NEXT: {{^    i = 5;$}}
+  // CHECK-FIXES-NEXT: {{^  }$}}
+  // CHECK-FIXES-NEXT: {{^  i = 7;$}}
+
+  i = 8;
+  if (false) {
+    i = 9;
+  }
+  i = 11;
+  // CHECK-MESSAGES: :[[@LINE-4]]:7: warning: {{.*}} in if statement condition
+  // CHECK-FIXES:      {{^  i = 8;$}}
+  // CHECK-FIXES-NEXT: {{^  $}}
+  // CHECK-FIXES-NEXT: {{^  i = 11;$}}
+}
+
+void operator_equals() {
+  int i = 0;
+  bool b1 = (i > 2);
+  if (b1 == true) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: {{.*}} to boolean operator
+    // CHECK-FIXES: {{^  if \(b1\) {$}}
+    i = 5;
+  } else {
+    i = 6;
+  }
+  bool b2 = (i > 4);
+  if (b2 == false) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: {{.*}} to boolean operator
+    // CHECK-FIXES: {{^  if \(!b2\) {$}}
+    i = 7;
+  } else {
+    i = 9;
+  }
+  bool b3 = (i > 6);
+  if (true == b3) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: {{.*}} to boolean operator
+    // CHECK-FIXES: {{^  if \(b3\) {$}}
+    i = 10;
+  } else {
+    i = 11;
+  }
+  bool b4 = (i > 8);
+  if (false == b4) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: {{.*}} to boolean operator
+    // CHECK-FIXES: {{^  if \(!b4\) {$}}
+    i = 12;
+  } else {
+    i = 13;
+  }
+}
+
+void operator_or() {
+  int i = 0;
+  bool b5 = (i > 10);
+  if (b5 || false) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: {{.*}} to boolean operator
+    // CHECK-FIXES: {{^  if \(b5\) {$}}
+    i = 14;
+  } else {
+    i = 15;
+  }
+  bool b6 = (i > 10);
+  if (b6 || true) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: {{.*}} to boolean operator
+    // CHECK-FIXES: {{^  if \(true\) {$}}
+    i = 16;
+  } else {
+    i = 17;
+  }
+  bool b7 = (i > 10);
+  if (false || b7) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: {{.*}} to boolean operator
+    // CHECK-FIXES: {{^  if \(b7\) {$}}
+    i = 18;
+  } else {
+    i = 19;
+  }
+  bool b8 = (i > 10);
+  if (true || b8) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: {{.*}} to boolean operator
+    // CHECK-FIXES: {{^  if \(true\) {$}}
+    i = 20;
+  } else {
+    i = 21;
+  }
+}
+
+void operator_and() {
+  int i = 0;
+  bool b9 = (i > 20);
+  if (b9 && false) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: {{.*}} to boolean operator
+    // CHECK-FIXES: {{^  if \(false\) {$}}
+    i = 22;
+  } else {
+    i = 23;
+  }
+  bool ba = (i > 20);
+  if (ba && true) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: {{.*}} to boolean operator
+    // CHECK-FIXES: {{^  if \(ba\) {$}}
+    i = 24;
+  } else {
+    i = 25;
+  }
+  bool bb = (i > 20);
+  if (false && bb) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: {{.*}} to boolean operator
+    // CHECK-FIXES: {{^  if \(false\) {$}}
+    i = 26;
+  } else {
+    i = 27;
+  }
+  bool bc = (i > 20);
+  if (true && bc) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: {{.*}} to boolean operator
+    // CHECK-FIXES: {{^  if \(bc\) {$}}
+    i = 28;
+  } else {
+    i = 29;
+  }
+}
+
+void ternary_operator() {
+  int i = 0;
+  bool bd = (i > 20) ? true : false;
+  // CHECK-MESSAGES: :[[@LINE-1]]:24: warning: {{.*}} in ternary expression result
+  // CHECK-FIXES: {{^  bool bd = i > 20;$}}
+
+  bool be = (i > 20) ? false : true;
+  // CHECK-MESSAGES: :[[@LINE-1]]:24: warning: {{.*}} in ternary expression result
+  // CHECK-FIXES: {{^  bool be = i <= 20;$}}
+
+  bool bf = ((i > 20)) ? false : true;
+  // CHECK-MESSAGES: :[[@LINE-1]]:26: warning: {{.*}} in ternary expression result
+  // CHECK-FIXES: {{^  bool bf = i <= 20;$}}
+}
+
+void operator_not_equal() {
+  int i = 0;
+  bool bf = (i > 20);
+  if (false != bf) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: {{.*}} to boolean operator
+    // CHECK-FIXES: {{^  if \(bf\) {$}}
+    i = 30;
+  } else {
+    i = 31;
+  }
+  bool bg = (i > 20);
+  if (true != bg) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: {{.*}} to boolean operator
+    // CHECK-FIXES: {{^  if \(!bg\) {$}}
+    i = 32;
+  } else {
+    i = 33;
+  }
+  bool bh = (i > 20);
+  if (bh != false) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: {{.*}} to boolean operator
+    // CHECK-FIXES: {{^  if \(bh\) {$}}
+    i = 34;
+  } else {
+    i = 35;
+  }
+  bool bi = (i > 20);
+  if (bi != true) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: {{.*}} to boolean operator
+    // CHECK-FIXES: {{^  if \(!bi\) {$}}
+    i = 36;
+  } else {
+    i = 37;
+  }
+}
+
+void nested_booleans() {
+  if (false || (true || false)) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:17: warning: {{.*}} to boolean operator
+    // CHECK-FIXES: {{^  if \(false \|\| \(true\)\) {$}}
+  }
+  if (true && (true || false)) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:16: warning: {{.*}} to boolean operator
+    // CHECK-FIXES: {{^  if \(true && \(true\)\) {$}}
+  }
+  if (false || (true && false)) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:17: warning: {{.*}} to boolean operator
+    // CHECK-FIXES: {{^  if \(false \|\| \(false\)\) {$}}
+  }
+  if (true && (true && false)) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:16: warning: {{.*}} to boolean operator
+    // CHECK-FIXES: {{^  if \(true && \(false\)\) {$}}
+  }
+}
+
+static constexpr bool truthy() {
+  return true;
+}
+
+#define HAS_XYZ_FEATURE true
+
+void macros_and_constexprs(int i = 0) {
+  bool b = (i == 1);
+  if (b && truthy()) {
+    // leave this alone; if you want it simplified, then you should
+    // inline the constexpr function first.
+    i = 1;
+  }
+  i = 2;
+  if (b && HAS_XYZ_FEATURE) {
+    // leave this alone; if you want it simplified, then you should
+    // inline the macro first.
+    i = 3;
+  }
+  i = 4;
+}
+
+bool conditional_return_statements(int i) {
+  if (i == 0) return true; else return false;
+}
+// CHECK-MESSAGES: :[[@LINE-2]]:22: warning: {{.*}} in conditional return statement
+// CHECK-FIXES:      {{^}}  return i == 0;{{$}}
+// CHECK-FIXES-NEXT: {{^}$}}
+
+bool conditional_return_statements_then_expr(int i, int j) {
+  if (i == j) return (i == 0); else return false;
+}
+
+bool conditional_return_statements_else_expr(int i, int j) {
+  if (i == j) return true; else return (i == 0);
+}
+
+bool negated_conditional_return_statements(int i) {
+  if (i == 0) return false; else return true;
+}
+// CHECK-MESSAGES: :[[@LINE-2]]:22: warning: {{.*}} in conditional return statement
+// CHECK-FIXES:      {{^}}  return i != 0;{{$}}
+// CHECK-FIXES-NEXT: {{^}$}}
+
+bool conditional_compound_return_statements(int i) {
+  if (i == 1) {
+    return true;
+  } else {
+    return false;
+  }
+}
+// CHECK-MESSAGES: :[[@LINE-5]]:12: warning: {{.*}} in conditional return statement
+// CHECK-FIXES:      {{^}}bool conditional_compound_return_statements(int i) {{{$}}
+// CHECK-FIXES-NEXT: {{^}}  return i == 1;{{$}}
+// CHECK-FIXES-NEXT: {{^}$}}
+
+bool negated_conditional_compound_return_statements(int i) {
+  if (i == 1) {
+    return false;
+  } else {
+    return true;
+  }
+}
+// CHECK-MESSAGES: :[[@LINE-5]]:12: warning: {{.*}} in conditional return statement
+// CHECK-FIXES:      {{^}}bool negated_conditional_compound_return_statements(int i) {{{$}}
+// CHECK-FIXES-NEXT: {{^}}  return i != 1;{{$}}
+// CHECK-FIXES-NEXT: {{^}$}}
+
+bool conditional_return_statements_side_effects_then(int i) {
+  if (i == 2) {
+    macros_and_constexprs();
+    return true;
+  } else
+    return false;
+}
+
+bool negated_conditional_return_statements_side_effects_then(int i) {
+  if (i == 2) {
+    macros_and_constexprs();
+    return false;
+  } else
+    return true;
+}
+
+bool conditional_return_statements_side_effects_else(int i) {
+  if (i == 2)
+    return true;
+  else {
+    macros_and_constexprs();
+    return false;
+  }
+}
+
+bool negated_conditional_return_statements_side_effects_else(int i) {
+  if (i == 2)
+    return false;
+  else {
+    macros_and_constexprs();
+    return true;
+  }
+}
+
+void lambda_conditional_return_statements() {
+  auto lambda = [](int n) -> bool { if (n > 0) return true; else return false; };
+  // CHECK-MESSAGES: :[[@LINE-1]]:55: warning: {{.*}} in conditional return statement
+  // CHECK-FIXES: {{^}}  auto lambda = [](int n) -> bool { return n > 0; };{{$}}
+
+  auto lambda2 = [](int n) -> bool {
+    if (n > 0) {
+        return true;
+    } else {
+        return false;
+    }
+  };
+  // CHECK-MESSAGES: :[[@LINE-5]]:16: warning: {{.*}} in conditional return statement
+  // CHECK-FIXES:      {{^}}  auto lambda2 = [](int n) -> bool {{{$}}
+  // CHECK-FIXES-NEXT: {{^}}    return n > 0;{{$}}
+  // CHECK-FIXES-NEXT: {{^}}  };{{$}}
+
+  auto lambda3 = [](int n) -> bool { if (n > 0) {macros_and_constexprs(); return true; } else return false; };
+
+  auto lambda4 = [](int n) -> bool {
+    if (n > 0)
+        return true;
+    else {
+        macros_and_constexprs();
+        return false;
+    }
+  };
+
+  auto lambda5 = [](int n) -> bool { if (n > 0) return false; else return true; };
+  // CHECK-MESSAGES: :[[@LINE-1]]:56: warning: {{.*}} in conditional return statement
+  // CHECK-FIXES: {{^}}  auto lambda5 = [](int n) -> bool { return n <= 0; };{{$}}
+
+  auto lambda6 = [](int n) -> bool {
+    if (n > 0) {
+        return false;
+    } else {
+        return true;
+    }
+  };
+  // CHECK-MESSAGES: :[[@LINE-5]]:16: warning: {{.*}} in conditional return statement
+  // CHECK-FIXES:      {{^}}  auto lambda6 = [](int n) -> bool {{{$}}
+  // CHECK-FIXES-NEXT: {{^}}    return n <= 0;{{$}}
+  // CHECK-FIXES-NEXT: {{^}}  };{{$}}
+}
+
+void simple_conditional_assignment_statements(int i) {
+  bool b;
+  if (i > 10)
+    b = true;
+  else
+    b = false;
+  bool bb = false;
+  // CHECK-MESSAGES: :[[@LINE-4]]:9: warning: {{.*}} in conditional assignment
+  // CHECK-FIXES: bool b;
+  // CHECK-FIXES: {{^  }}b = i > 10;{{$}}
+  // CHECK-FIXES: bool bb = false;
+
+  bool c;
+  if (i > 20)
+    c = false;
+  else
+    c = true;
+  bool c2 = false;
+  // CHECK-MESSAGES: :[[@LINE-4]]:9: warning: {{.*}} in conditional assignment
+  // CHECK-FIXES: bool c;
+  // CHECK-FIXES: {{^  }}c = i <= 20;{{$}}
+  // CHECK-FIXES: bool c2 = false;
+
+  // unchanged; different variables
+  bool b2;
+  if (i > 12)
+    b = true;
+  else
+    b2 = false;
+
+  // unchanged; no else statement
+  bool b3;
+  if (i > 15)
+    b3 = true;
+
+  // unchanged; not boolean assignment
+  int j;
+  if (i > 17)
+    j = 10;
+  else
+    j = 20;
+
+  // unchanged; different variables assigned
+  int k = 0;
+  bool b4 = false;
+  if (i > 10)
+    b4 = true;
+  else
+    k = 10;
+}
+
+void complex_conditional_assignment_statements(int i) {
+  bool d;
+  if (i > 30) {
+    d = true;
+  } else {
+    d = false;
+  }
+  d = false;
+  // CHECK-MESSAGES: :[[@LINE-5]]:9: warning: {{.*}} in conditional assignment
+  // CHECK-FIXES: bool d;
+  // CHECK-FIXES: {{^  }}d = i > 30;{{$}}
+  // CHECK-FIXES: d = false;
+
+  bool e;
+  if (i > 40) {
+    e = false;
+  } else {
+    e = true;
+  }
+  e = false;
+  // CHECK-MESSAGES: :[[@LINE-5]]:9: warning: {{.*}} in conditional assignment
+  // CHECK-FIXES: bool e;
+  // CHECK-FIXES: {{^  }}e = i <= 40;{{$}}
+  // CHECK-FIXES: e = false;
+
+  // unchanged; no else statement
+  bool b3;
+  if (i > 15) {
+    b3 = true;
+  }
+
+  // unchanged; not a boolean assignment
+  int j;
+  if (i > 17) {
+    j = 10;
+  } else {
+    j = 20;
+  }
+
+  // unchanged; multiple statements
+  bool f;
+  if (j > 10) {
+    j = 10;
+    f = true;
+  } else {
+    j = 20;
+    f = false;
+  }
+
+  // unchanged; multiple statements
+  bool g;
+  if (j > 10)
+    f = true;
+  else {
+    j = 20;
+    f = false;
+  }
+
+  // unchanged; multiple statements
+  bool h;
+  if (j > 10) {
+    j = 10;
+    f = true;
+  } else
+    f = false;
+}