[clang-tidy] Add delete null pointer check.

This check detects and fixes redundant null checks before deletes.

Patch by: Gergely Angeli!

Differential Revision: https://reviews.llvm.org/D21298

llvm-svn: 290784

1 files changed, 76 insertions, 0 deletions

diff --git a/clang-tools-extra/test/clang-tidy/readability-delete-null-pointer.cpp b/clang-tools-extra/test/clang-tidy/readability-delete-null-pointer.cpp
new file mode 100644
index 00000000000..400714b44d9
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/readability-delete-null-pointer.cpp
@@ -0,0 +1,76 @@
+// RUN: %check_clang_tidy %s readability-delete-null-pointer %t
+
+#define NULL 0
+
+void f() {
+  int *p = 0;
+
+  // #1
+  if (p) { // #2
+    delete p;
+  } // #3
+  // CHECK-MESSAGES: :[[@LINE-3]]:3: warning: 'if' statement is unnecessary; deleting null pointer has no effect [readability-delete-null-pointer]
+
+  // CHECK-FIXES: {{^  }}// #1
+  // CHECK-FIXES-NEXT: {{^  }}// #2
+  // CHECK-FIXES-NEXT: delete p;
+  // CHECK-FIXES-NEXT: {{^  }}// #3
+
+  int *p2 = new int[3];
+  // #4
+  if (p2) // #5
+    delete[] p2;
+  // CHECK-MESSAGES: :[[@LINE-2]]:3: warning: 'if' statement is unnecessary;
+
+  // CHECK-FIXES: // #4
+  // CHECK-FIXES-NEXT: {{^  }}// #5
+  // CHECK-FIXES-NEXT: delete[] p2;
+
+  int *p3 = 0;
+  if (NULL != p3) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: 'if' statement is unnecessary;
+    delete p3;
+  }
+  // CHECK-FIXES-NOT: if (NULL != p3) {
+  // CHECK-FIXES: delete p3;
+
+  int *p4 = nullptr;
+  if (p4 != nullptr) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: 'if' statement is unnecessary;
+    delete p4;
+  }
+  // CHECK-FIXES-NOT: if (p4 != nullptr) {
+  // CHECK-FIXES: delete p4;
+
+  char *c;
+  if (c != 0) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: 'if' statement is unnecessary;
+    delete c;
+  }
+  // CHECK-FIXES-NOT: if (c != 0) {
+  // CHECK-FIXES: delete c;
+
+  char *c2;
+  if (c2) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: 'if' statement is unnecessary;
+    // CHECK-FIXES: } else {
+    // CHECK-FIXES: c2 = c;
+    delete c2;
+  } else {
+    c2 = c;
+  }
+}
+
+void g() {
+  int *p5, *p6;
+  if (p5)
+    delete p6;
+
+  if (p5 && p6)
+    delete p5;
+
+  if (p6) {
+    int x = 5;
+    delete p6;
+  }
+}