Implement -Wparentheses: warn about using assignments in contexts that require

conditions.  Add a fixit to insert the parentheses.  Also fix a very minor
possible memory leak in 'for' conditions.

Fixes PR 4876 and rdar://problem/7289172

llvm-svn: 83907

1 files changed, 65 insertions, 0 deletions

diff --git a/clang/test/SemaCXX/warn-assignment-condition.cpp b/clang/test/SemaCXX/warn-assignment-condition.cpp
new file mode 100644
index 00000000000..3b9f3066a16
--- /dev/null
+++ b/clang/test/SemaCXX/warn-assignment-condition.cpp
@@ -0,0 +1,65 @@
+// RUN: clang-cc -fsyntax-only -Wparentheses -verify %s
+
+struct A {
+  int foo();
+  friend A operator+(const A&, const A&);
+  operator bool();
+};
+
+void test() {
+  int x, *p;
+  A a, b;
+
+  // With scalars.
+  if (x = 7) {} // expected-warning {{using the result of an assignment as a condition without parentheses}}
+  if ((x = 7)) {}
+  do {
+  } while (x = 7); // expected-warning {{using the result of an assignment as a condition without parentheses}}
+  do {
+  } while ((x = 7));
+  while (x = 7) {} // expected-warning {{using the result of an assignment as a condition without parentheses}}
+  while ((x = 7)) {}
+  for (; x = 7; ) {} // expected-warning {{using the result of an assignment as a condition without parentheses}}
+  for (; (x = 7); ) {}
+
+  if (p = p) {} // expected-warning {{using the result of an assignment as a condition without parentheses}}
+  if ((p = p)) {}
+  do {
+  } while (p = p); // expected-warning {{using the result of an assignment as a condition without parentheses}}
+  do {
+  } while ((p = p));
+  while (p = p) {} // expected-warning {{using the result of an assignment as a condition without parentheses}}
+  while ((p = p)) {}
+  for (; p = p; ) {} // expected-warning {{using the result of an assignment as a condition without parentheses}}
+  for (; (p = p); ) {}
+
+  // Initializing variables (shouldn't warn).
+  if (int y = x) {}
+  while (int y = x) {}
+  if (A y = a) {}
+  while (A y = a) {}
+
+  // With temporaries.
+  if (x = (b+b).foo()) {} // expected-warning {{using the result of an assignment as a condition without parentheses}}
+  if ((x = (b+b).foo())) {}
+  do {
+  } while (x = (b+b).foo()); // expected-warning {{using the result of an assignment as a condition without parentheses}}
+  do {
+  } while ((x = (b+b).foo()));
+  while (x = (b+b).foo()) {} // expected-warning {{using the result of an assignment as a condition without parentheses}}
+  while ((x = (b+b).foo())) {}
+  for (; x = (b+b).foo(); ) {} // expected-warning {{using the result of an assignment as a condition without parentheses}}
+  for (; (x = (b+b).foo()); ) {}
+
+  // With a user-defined operator.
+  if (a = b + b) {} // expected-warning {{using the result of an assignment as a condition without parentheses}}
+  if ((a = b + b)) {}
+  do {
+  } while (a = b + b); // expected-warning {{using the result of an assignment as a condition without parentheses}}
+  do {
+  } while ((a = b + b));
+  while (a = b + b) {} // expected-warning {{using the result of an assignment as a condition without parentheses}}
+  while ((a = b + b)) {}
+  for (; a = b + b; ) {} // expected-warning {{using the result of an assignment as a condition without parentheses}}
+  for (; (a = b + b); ) {}
+}