PR c/89425 - -Wabsolute-value warns in dead subexpressions

gcc/c/ChangeLog:

	PR c/89425
	* c-parser.c (sizeof_ptr_memacc_comptypes): Avoid warning in
	unreachable subexpressions.

gcc/testsuite/ChangeLog:

	PR c/89425
	* gcc.dg/Wabsolute-value.c: New test.

From-SVN: r269121

gcc/ChangeLog

+2019-02-22  Martin Sebor  <msebor@redhat.com>
+
+	PR c/89425
+	* c-parser.c (sizeof_ptr_memacc_comptypes): Avoid warning in
+	unreachable subexpressions.
+
 2019-02-22  H.J. Lu  <hongjiu.lu@intel.com>
 	    Hongtao Liu  <hongtao.liu@intel.com>
 	    Sunil K Pandey  <sunil.k.pandey@intel.com>

gcc/c/c-parser.c

@@ -9374,6 +9374,10 @@ sizeof_ptr_memacc_comptypes (tree type1, tree type2)
 static void
 warn_for_abs (location_t loc, tree fndecl, tree arg)
 {
+  /* Avoid warning in unreachable subexpressions.  */
+  if (c_inhibit_evaluation_warnings)
+    return;
+
   tree atype = TREE_TYPE (arg);
 
   /* Casts from pointers (and thus arrays and fndecls) will generate

gcc/testsuite/ChangeLog

 2019-02-22  Martin Sebor  <msebor@redhat.com>
 
+	PR c/89425
+	* gcc.dg/Wabsolute-value.c: New test.
+
 	* gcc.dg/Wbuiltin-declaration-mismatch-12.c: New test.
 
 2019-02-22  H.J. Lu  <hongjiu.lu@intel.com>

gcc/testsuite/gcc.dg/Wabsolute-value.c

+/* PR c/89425 - -Wabsolute-value warns in dead subexpressions
+   { dg-do compile }
+   { dg-options "-Wabsolute-value -ftrack-macro-expansion=0" } */
+
+struct Vals
+{
+  signed char sc;
+  signed short ss;
+  signed int si;
+  signed long sl;
+  signed long long sll;
+
+  unsigned char uc;
+  unsigned short us;
+  unsigned int ui;
+  unsigned long ul;
+  unsigned long long ull;
+
+  float f;
+  double d;
+  long double ld;
+};
+
+#define abs(x)     __builtin_abs (x)
+#define labs(x)    __builtin_labs (x)
+#define llabs(x)   __builtin_llabs (x)
+
+#define fabsf(x)   __builtin_fabsf (x)
+#define fabs(x)    __builtin_fabs (x)
+
+
+void tst_warn (struct Vals *p)
+{
+  /* Verify that "-Wabsolute-value is issued for subexpressions
+     that are evaluated.  */
+
+  p->uc =  0 ? abs (p->sc) : abs (p->uc);         /* { dg-warning "\\\[-Wabsolute-value]" } */
+  p->us =  0 ? abs (p->ss) : abs (p->us);         /* { dg-warning "\\\[-Wabsolute-value]" } */
+  p->ui =  0 ? abs (p->si) : abs (p->ui);         /* { dg-warning "\\\[-Wabsolute-value]" } */
+  p->ul =  0 ? labs (p->sl) : labs (p->ul);       /* { dg-warning "\\\[-Wabsolute-value]" } */
+  p->ull = 0 ? llabs (p->sll) : llabs (p->ull);   /* { dg-warning "\\\[-Wabsolute-value]" } */
+
+  p->d   = 0 ? fabs (p->d) : fabsf (p->d);        /* { dg-warning "\\\[-Wabsolute-value]" } */
+}
+
+void tst_no_warn (struct Vals *p)
+{
+  /* Verify that "-Wabsolute-value is not issued for subexpressions
+     that are not evaluated.  */
+
+  p->uc =  0 ? abs (p->uc) : abs (p->sc);
+  p->us =  0 ? abs (p->us) : abs (p->ss);
+  p->ui =  0 ? abs (p->ui) : abs (p->si);
+  p->ul =  0 ? labs (p->ul) : labs (p->sl);
+  p->ull = 0 ? llabs (p->ull) : llabs (p->sll);
+  p->d   = 0 ? fabsf (p->d) : fabs (p->d);
+}