Improve the unused-value check to look into comma expressions and filter out

voids in sub-expressions.  Patch by Mike M!

Fixes PR4806.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@98335 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 53 insertions, 0 deletions

diff --git a/test/Sema/warn-unused-value.c b/test/Sema/warn-unused-value.c
new file mode 100644
index 0000000000..2e0fa54eff
--- /dev/null
+++ b/test/Sema/warn-unused-value.c
@@ -0,0 +1,53 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -Wunused-value %s
+
+int i = 0;
+int j = 0;
+
+void foo();
+
+// PR4806
+void pr4806() {
+  1,foo();          // expected-warning {{expression result unused}}
+
+  // other
+  foo();
+  i;                // expected-warning {{expression result unused}}
+
+  i,foo();          // expected-warning {{expression result unused}}
+  foo(),i;          // expected-warning {{expression result unused}}
+
+  i,j,foo();        // expected-warning {{expression result unused}}
+  i,foo(),j;        // expected-warning {{expression result unused}}
+  foo(),i,j;        // expected-warning {{expression result unused}}
+
+  i++;
+
+  i++,foo();
+  foo(),i++;
+
+  i++,j,foo();      // expected-warning {{expression result unused}}
+  i++,foo(),j;      // expected-warning {{expression result unused}}
+  foo(),i++,j;      // expected-warning {{expression result unused}}
+
+  i,j++,foo();      // expected-warning {{expression result unused}}
+  i,foo(),j++;      // expected-warning {{expression result unused}}
+  foo(),i,j++;      // expected-warning {{expression result unused}}
+
+  i++,j++,foo();
+  i++,foo(),j++;
+  foo(),i++,j++;
+
+  {};
+  ({});
+  ({}),foo();
+  foo(),({});
+
+  (int)1U;          // expected-warning {{expression result unused}}
+  (void)1U;
+
+  // pointer to volatile has side effect (thus no warning)
+  int* pi = &i;
+  volatile int* pj = &j;
+  *pi;              // expected-warning {{expression result unused}}
+  *pj;
+}