[clang-tidy] Add a checker for implicit bool conversion of a bool*.

The goal is to find code like the example below, which is likely a typo
where someone meant to write "if (*b)".
bool *b = SomeFunction();
 if (b) {
   // b never dereferenced
 }

This checker naturally has a relatively high false positive rate so it
applies some heuristics to avoid cases where the pointer is checked for
nullptr before being written.

Differential Revision: http://reviews.llvm.org/D4458

llvm-svn: 212797

1 files changed, 86 insertions, 0 deletions

diff --git a/clang-tools-extra/test/clang-tidy/misc-bool-pointer-implicit-conversion.cpp b/clang-tools-extra/test/clang-tidy/misc-bool-pointer-implicit-conversion.cpp
new file mode 100644
index 00000000000..98cfd667242
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/misc-bool-pointer-implicit-conversion.cpp
@@ -0,0 +1,86 @@
+// RUN: $(dirname %s)/check_clang_tidy_fix.sh %s misc-bool-pointer-implicit-conversion %t
+// REQUIRES: shell
+
+bool *SomeFunction();
+void SomeOtherFunction(bool*);
+bool F();
+void G(bool);
+
+
+template <typename T>
+void t(T b) {
+  if (b) {
+  }
+}
+
+void foo() {
+  bool *b = SomeFunction();
+  if (b) {
+// CHECK-MESSAGES: dubious check of 'bool *' against 'nullptr'
+// CHECK-FIXES: if (*b) {
+  }
+
+  if (F() && b) {
+// CHECK-MESSAGES: dubious check of 'bool *' against 'nullptr'
+// CHECK-FIXES: if (F() && *b) {
+  }
+
+  // TODO: warn here.
+  if (b) {
+    G(b);
+  }
+
+#define TESTMACRO if (b || F())
+
+  TESTMACRO {
+// CHECK-MESSAGES: dubious check of 'bool *' against 'nullptr'
+// Can't fix this.
+// CHECK-FIXES: #define TESTMACRO if (b || F())
+// CHECK-FIXES: TESTMACRO {
+  }
+
+// CHECK-MESSAGES-NOT: warning:
+
+  t(b);
+
+  if (!b) {
+    // no-warning
+  }
+
+  if (SomeFunction()) {
+    // no-warning
+  }
+
+  bool *c = SomeFunction();
+  if (c) {
+    (void)c;
+    (void)*c; // no-warning
+  }
+
+  if (c) {
+    *c = true; // no-warning
+  }
+
+  if (c) {
+    c[0] = false; // no-warning
+  }
+
+  if (c) {
+    SomeOtherFunction(c); // no-warning
+  }
+
+  if (c) {
+    delete[] c; // no-warning
+  }
+
+  if (c) {
+    *(c) = false; // no-warning
+  }
+
+  struct {
+    bool *b;
+  } d = { SomeFunction() };
+
+  if (d.b)
+    (void)*d.b; // no-warning
+}