[Diagnostics] Warn if ?: with integer constants always evaluates to true

Extracted from D63082. GCC has this warning under -Wint-in-bool-context, but as noted in the D63082's review, we should put it under TautologicalConstantCompare.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@372531 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 32 insertions, 0 deletions

diff --git a/test/Sema/warn-integer-constants-in-ternary.c b/test/Sema/warn-integer-constants-in-ternary.c
new file mode 100644
index 0000000000..287b91ecdb
--- /dev/null
+++ b/test/Sema/warn-integer-constants-in-ternary.c
@@ -0,0 +1,32 @@
+// RUN: %clang_cc1 -x c -fsyntax-only -verify -Wtautological-constant-compare %s
+// RUN: %clang_cc1 -x c -fsyntax-only -verify %s
+// RUN: %clang_cc1 -x c++ -fsyntax-only -verify -Wtautological-constant-compare %s
+// RUN: %clang_cc1 -x c++ -fsyntax-only -verify %s
+
+#define ONE 1
+#define TWO 2
+
+#define TERN(c, l, r) c ? l : r
+
+#ifdef __cplusplus
+typedef bool boolean;
+#else
+typedef _Bool boolean;
+#endif
+
+void test(boolean a) {
+  boolean r;
+  r = a ? (1) : TWO;
+  r = a ? 3 : TWO; // expected-warning {{converting the result of '?:' with integer constants to a boolean always evaluates to 'true'}}
+  r = a ? -2 : 0;  // expected-warning {{converting the result of '?:' with integer constants to a boolean always evaluates to 'true'}}
+  r = a ? 3 : -2;  // expected-warning {{converting the result of '?:' with integer constants to a boolean always evaluates to 'true'}}
+  r = a ? 0 : TWO;
+  r = a ? 3 : ONE; // expected-warning {{converting the result of '?:' with integer constants to a boolean always evaluates to 'true'}}
+  r = a ? ONE : 0;
+  r = a ? 0 : -0;
+  r = a ? 1 : 0;
+  r = a ? ONE : 0;
+  r = a ? ONE : ONE;
+  r = TERN(a, 4, 8);   // expected-warning {{converting the result of '?:' with integer constants to a boolean always evaluates to 'true'}}
+  r = TERN(a, -1, -8); // expected-warning {{converting the result of '?:' with integer constants to a boolean always evaluates to 'true'}}
+}