diff --git a/src/dmd/backend/elfobj.d b/src/dmd/backend/elfobj.d
index 157b7ffa979b..d0975ad07b77 100644
--- a/src/dmd/backend/elfobj.d
+++ b/src/dmd/backend/elfobj.d
@@ -1959,9 +1959,12 @@ private int elf_addsegment2(IDXSEC shtidx, IDXSYM symidx, IDXSEC relidx)
     }
     assert(seg_count < seg_max);
     if (!SegData[seg])
-    {   SegData[seg] = cast(seg_data *)mem_calloc((seg_data).sizeof);
+    {
+        SegData[seg] = cast(seg_data *)mem_calloc(seg_data.sizeof);
         //printf("test2: SegData[%d] = %p\n", seg, SegData[seg]);
     }
+    else
+        memset(SegData[seg], 0, seg_data.sizeof);
 
     seg_data *pseg = SegData[seg];
     pseg.SDseg = seg;
diff --git a/src/dmd/semantic3.d b/src/dmd/semantic3.d
index 6f722e947f19..06800e21cfa0 100644
--- a/src/dmd/semantic3.d
+++ b/src/dmd/semantic3.d
@@ -529,7 +529,7 @@ private extern(C++) final class Semantic3Visitor : Visitor
                     if (auto s = funcdecl.fensure.isScopeStatement())
                         fensure_endlin = s.endloc.linnum;
 
-                if ((needEnsure && global.params.useOut) || fpostinv)
+                if ((needEnsure && global.params.useOut == CHECKENABLE.on) || fpostinv)
                 {
                     funcdecl.returnLabel = new LabelDsymbol(Id.returnLabel);
                 }
@@ -903,7 +903,7 @@ private extern(C++) final class Semantic3Visitor : Visitor
 
                 sc2 = sc2.pop();
 
-                if (!global.params.useIn)
+                if (global.params.useIn == CHECKENABLE.off)
                     freq = null;
             }
             if (fens)
@@ -937,7 +937,7 @@ private extern(C++) final class Semantic3Visitor : Visitor
 
                 sc2 = sc2.pop();
 
-                if (!global.params.useOut)
+                if (global.params.useOut == CHECKENABLE.off)
                     fens = null;
             }
             if (funcdecl.fbody && funcdecl.fbody.isErrorStatement())
diff --git a/test/runnable/extra-files/lib18456b.d b/test/runnable/extra-files/lib18456b.d
new file mode 100644
index 000000000000..714d8cf9a616
--- /dev/null
+++ b/test/runnable/extra-files/lib18456b.d
@@ -0,0 +1,12 @@
+module manual;
+
+class ManualGC {
+    void enable()
+    {
+    }
+
+    void disable()
+    {
+    }
+
+}
diff --git a/test/runnable/test16096.sh b/test/runnable/test16096.sh
index 77fe08767e96..697cc439dd15 100755
--- a/test/runnable/test16096.sh
+++ b/test/runnable/test16096.sh
@@ -6,7 +6,7 @@ if [ "$OS" != 'osx' ] || [ "$MODEL" != '64' ]; then
 fi
 
 $DMD -I${EXTRA_FILES} -of${OUTPUT_BASE}${LIBEXT} -lib ${EXTRA_FILES}/test16096a.d
-$DMD -I${EXTRA_FILES} -of${OUTPUT_BASE}${EXT} ${EXTRA_FILES}/test16096.d ${OUTPUT_BASE}${LIBEXT} -L-framework -LFoundation
+$DMD -I${EXTRA_FILES} -of${OUTPUT_BASE}${EXE} ${EXTRA_FILES}/test16096.d ${OUTPUT_BASE}${LIBEXT} -L-framework -LFoundation
 ${OUTPUT_BASE}${EXE}
 
 rm ${OUTPUT_BASE}{${LIBEXT},${EXE}}
diff --git a/test/runnable/test18456.sh b/test/runnable/test18456.sh
index 9f4e8bba0ecd..eeaae0d96a4f 100644
--- a/test/runnable/test18456.sh
+++ b/test/runnable/test18456.sh
@@ -1,6 +1,7 @@
 #!/usr/bin/env bash
 
-$DMD -m${MODEL} -I${EXTRA_FILES} -of${OUTPUT_BASE}${LIBEXT} -lib ${EXTRA_FILES}/lib18456.d
+# source file order is important
+$DMD -m${MODEL} -I${EXTRA_FILES} -of${OUTPUT_BASE}${LIBEXT} -lib ${EXTRA_FILES}/lib18456b.d ${EXTRA_FILES}/lib18456.d
 $DMD -m${MODEL} -I${EXTRA_FILES} -of${OUTPUT_BASE}${EXE} ${EXTRA_FILES}/test18456.d ${OUTPUT_BASE}${LIBEXT}
 ${OUTPUT_BASE}${EXE}
 
diff --git a/test/runnable/test_dip1006.d b/test/runnable/test_dip1006.d
new file mode 100644
index 000000000000..d8a8b4bccc93
--- /dev/null
+++ b/test/runnable/test_dip1006.d
@@ -0,0 +1,38 @@
+// REQUIRED_ARGS: -check=in=off -check=out=off -check=invariant=off
+// PERMUTE_ARGS:
+class C
+{
+    int foo(int a)
+    in { assert(a != 0); } // skipped
+    out(res) { assert(res != 0); } // skipped
+    body
+    {
+        return a;
+    }
+
+    invariant // skipped
+    {
+        assert(false);
+    }
+
+    void bar(int a)
+    {
+        assert(a != 0); // triggered
+    }
+}
+
+void main()
+{
+    import core.exception : AssertError;
+
+    auto c = new C;
+    c.foo(0);
+
+    bool catched;
+    try
+        c.bar(0);
+    catch (AssertError e)
+        catched = true;
+    if (!catched)
+        assert(0);
+}
diff --git a/test/runnable/test_dip1006b.d b/test/runnable/test_dip1006b.d
new file mode 100644
index 000000000000..e64efbacac4d
--- /dev/null
+++ b/test/runnable/test_dip1006b.d
@@ -0,0 +1,35 @@
+// REQUIRED_ARGS: -check=in=off -check=invariant=off
+// PERMUTE_ARGS:
+class C
+{
+    int foo(int a)
+    in { assert(a != 0); } // skipped
+    out(res) { assert(res != 0, "out"); } // triggered
+    body
+    {
+        return a;
+    }
+
+    invariant // skipped
+    {
+        assert(false);
+    }
+}
+
+void main()
+{
+    import core.exception : AssertError;
+
+    auto c = new C;
+    bool catched;
+    try
+        c.foo(0);
+    catch (AssertError e)
+    {
+        assert(e.msg == "out");
+        catched = e.msg == "out";
+    }
+
+    if (!catched)
+        assert(0);
+}