test: discard unused results

regression-tests/pure2-last-use.cpp2

@@ -311,10 +311,10 @@ issue_857_4: @struct type = {
   /*h2*/ else if true { _ = that.mf(); }
   /*h3*/ else if true { _ = that.f; }
   /*h4*/ else if true { _ = x.mg(); }
-  /*h5*/ else if true { f() + x.g(); }
-  /*h6*/ else if true { x.g() + f(); }
-  /*h7*/ else if true { this.f() + x.g(); }
-  /*h8*/ else if true { x.g() + this.f(); }
+  /*h5*/ else if true { _ = f() + x.g(); }
+  /*h6*/ else if true { _ = x.g() + f(); }
+  /*h7*/ else if true { _ = this.f() + x.g(); }
+  /*h8*/ else if true { _ = x.g() + this.f(); }
   /*i0*/ else if true {
   /*i0*/   _ = f();
   /*i0*/   _ = x.mg();

regression-tests/test-results/pure2-last-use.cpp

@@ -719,10 +719,10 @@ int gi {0};
   else {if (true) {static_cast<void>(CPP2_UFCS_MOVE(mf)(that)); }/*h2*/
   else {if (true) {static_cast<void>(that.f); }/*h3*/
   else {if (true) {static_cast<void>(CPP2_UFCS_MOVE(mg)(std::move(x))); }/*h4*/
-  else {if (true) {f() + CPP2_UFCS_MOVE(g)(std::move(x)); }/*h5*/
-  else {if (true) {CPP2_UFCS(g)(std::move(x)) + std::move(*this).f(); }/*h6*/
-  else {if (true) {CPP2_UFCS(f)((*this)) + CPP2_UFCS_MOVE(g)(std::move(x)); }/*h7*/
-  else {if (true) {CPP2_UFCS(g)(std::move(x)) + CPP2_UFCS(f)(std::move((*this))); }/*h8*/
+  else {if (true) {static_cast<void>(f() + CPP2_UFCS_MOVE(g)(std::move(x))); }/*h5*/
+  else {if (true) {static_cast<void>(CPP2_UFCS(g)(std::move(x)) + std::move(*this).f()); }/*h6*/
+  else {if (true) {static_cast<void>(CPP2_UFCS(f)((*this)) + CPP2_UFCS_MOVE(g)(std::move(x))); }/*h7*/
+  else {if (true) {static_cast<void>(CPP2_UFCS(g)(std::move(x)) + CPP2_UFCS(f)(std::move((*this)))); }/*h8*/
   else {if (true) {/*i0*/
   static_cast<void>(f());/*i0*/
   static_cast<void>(CPP2_UFCS_MOVE(mg)(std::move(x)));/*i0*/