Add a new check, readability-redundant-control-flow, that check for some forms of redundant control flow statements. Currently checks for return statements at the end of a function with a void return type and continue statements at the end of looping statements.

Patch by Richard Thomson.

llvm-svn: 259362

1 files changed, 222 insertions, 0 deletions

diff --git a/clang-tools-extra/test/clang-tidy/readability-redundant-control-flow.cpp b/clang-tools-extra/test/clang-tidy/readability-redundant-control-flow.cpp
new file mode 100644
index 00000000000..09dec6f6b8e
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/readability-redundant-control-flow.cpp
@@ -0,0 +1,222 @@
+// RUN: %check_clang_tidy %s readability-redundant-control-flow %t
+
+void g(int i);
+void j();
+
+void f() {
+  return;
+}
+// CHECK-MESSAGES: :[[@LINE-2]]:3: warning: redundant return statement at the end of a function with a void return type [readability-redundant-control-flow]
+// CHECK-FIXES: {{^}}void f() {{{$}}
+// CHECK-FIXES-NEXT: {{^ *}$}}
+
+void g() {
+  f();
+  return;
+}
+// CHECK-MESSAGES: :[[@LINE-2]]:3: warning: redundant return statement
+// CHECK-FIXES: {{^  }}f();{{$}}
+// CHECK-FIXES-NEXT: {{^ *}$}}
+
+void g(int i) {
+  if (i < 0) {
+    return;
+  }
+  if (i < 10) {
+    f();
+  }
+}
+
+int h() {
+  return 1;
+}
+
+void j() {
+}
+
+void k() {
+  for (int i = 0; i < 10; ++i) {
+    continue;
+  }
+}
+// CHECK-MESSAGES: :[[@LINE-3]]:5: warning: redundant continue statement at the end of loop statement
+// CHECK-FIXES: {{^}}  for (int i = 0; i < 10; ++i) {{{$}}
+// CHECK-FIXES-NEXT: {{^ *}$}}
+
+void k2() {
+  int v[10] = { 0 };
+  for (auto i : v) {
+    continue;
+  }
+}
+// CHECK-MESSAGES: :[[@LINE-3]]:5: warning: redundant continue statement
+// CHECK-FIXES: {{^}}  for (auto i : v) {{{$}}
+// CHECK-FIXES-NEXT: {{^ *}$}}
+
+void m() {
+  int i = 0;
+  do {
+    ++i;
+    continue;
+  } while (i < 10);
+}
+// CHECK-MESSAGES: :[[@LINE-3]]:5: warning: redundant continue statement
+// CHECK-FIXES: {{^  do {$}}
+// CHECK-FIXES-NEXT: {{^}}    ++i;{{$}}
+// CHECK-FIXES-NEXT: {{^ *}}} while (i < 10);{{$}}
+
+void p() {
+  int i = 0;
+  while (i < 10) {
+    ++i;
+    continue;
+  }
+}
+// CHECK-MESSAGES: :[[@LINE-3]]:5: warning: redundant continue statement
+// CHECK-FIXES: {{^}}  while (i < 10) {{{$}}
+// CHECK-FIXES-NEXT: {{^}}    ++i;{{$}}
+// CHECK-FIXES-NEXT: {{^ *}$}}
+
+void im_not_dead(int i) {
+  if (i > 0) {
+    return;
+  }
+  g();
+}
+
+void im_still_not_dead(int i) {
+  for (int j = 0; j < 10; ++j) {
+    if (i < 10) {
+      continue;
+    }
+    g();
+  }
+}
+
+void im_dead(int i) {
+  if (i > 0) {
+    return;
+    g();
+  }
+  g();
+}
+
+void im_still_dead(int i) {
+  for (int j = 0; j < 10; ++j) {
+    if (i < 10) {
+      continue;
+      g();
+    }
+    g();
+  }
+}
+
+void void_return() {
+  return g();
+}
+
+void nested_return_unmolested() {
+  g();
+  {
+    g();
+    return;
+  }
+}
+
+void nested_continue_unmolested() {
+  for (int i = 0; i < 10; ++i) {
+    if (i < 5) {
+      continue;
+    }
+  }
+}
+
+#define MACRO_RETURN_UNMOLESTED(fn_)  \
+  (fn_)();                            \
+  return
+
+#define MACRO_CONTINUE_UNMOLESTED(x_) \
+  do {                                \
+    for (int i = 0; i < (x_); ++i) {  \
+      continue;                       \
+    }                                 \
+  } while (false)
+
+void macro_return() {
+  MACRO_RETURN_UNMOLESTED(g);
+}
+
+void macro_continue() {
+  MACRO_CONTINUE_UNMOLESTED(10);
+}
+
+#define MACRO_RETURN_ARG(stmt_) \
+  stmt_
+
+#define MACRO_CONTINUE_ARG(stmt_)   \
+  do {                              \
+    for (int i = 0; i < 10; ++i) {  \
+      stmt_;                        \
+    }                               \
+  } while (false)
+
+void macro_arg_return() {
+  MACRO_RETURN_ARG(return);
+}
+
+void macro_arg_continue() {
+  MACRO_CONTINUE_ARG(continue);
+}
+
+template <typename T>
+void template_return(T check) {
+  if (check < T(0)) {
+    return;
+  }
+  return;
+}
+// CHECK-MESSAGES: :[[@LINE-2]]:3: warning: redundant return statement
+// CHECK-FIXES: {{^}}  if (check < T(0)) {{{$}}
+// CHECK-FIXES-NEXT: {{^    return;$}}
+// CHECK-FIXES-NEXT: {{^ *}$}}
+
+template <>
+void template_return(int check) {
+  if (check < 0) {
+    return;
+  }
+  return;
+}
+// CHECK-MESSAGES: :[[@LINE-2]]:3: warning: redundant return statement
+// CHECK-FIXES: {{^}}  if (check < 0) {{{$}}
+// CHECK-FIXES-NEXT: {{^    return;$}}
+// CHECK-FIXES-NEXT: {{^ *}$}}
+
+template <typename T>
+void template_loop(T end) {
+  for (T i = 0; i < end; ++i) {
+    continue;
+  }
+}
+// CHECK-MESSAGES: :[[@LINE-3]]:5: warning: redundant continue statement
+// CHECK-FIXES: {{^}}  for (T i = 0; i < end; ++i) {{{$}}
+// CHECK-FIXES-NEXT: {{^ *}$}}
+
+template <>
+void template_loop(int end) {
+  for (int i = 0; i < end; ++i) {
+    continue;
+  }
+}
+// CHECK-MESSAGES: :[[@LINE-3]]:5: warning: redundant continue statement
+// CHECK-FIXES: {{^}}  for (int i = 0; i < end; ++i) {{{$}}
+// CHECK-FIXES-NEXT: {{^ *}$}}
+
+void call_templates() {
+  template_return(10);
+  template_return(10.0f);
+  template_return(10.0);
+  template_loop(10);
+  template_loop(10L);
+  template_loop(10U);
+}