Fix Issue 13947 - Padding in empty structs is compared

dlang · Jan 7, 2015 · bb98439 · bb98439
1 parent 98a4c74
commit bb98439
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Showing 2 changed files with 34 additions and 2 deletions.
diff --git a/src/e2ir.c b/src/e2ir.c
@@ -2130,7 +2130,12 @@ elem *toElem(Expression *e, IRState *irs)
 
             //printf("EqualExp::toElem()\n");
             elem *e;
-            if (t1->ty == Tstruct)
+            if (t1->ty == Tstruct && ((TypeStruct *)t1)->sym->fields.dim == 0)
+            {
+                // we can skip the compare if the structs are empty
+                e = el_long(TYbool, ee->op == TOKequal);
+            }
+            else if (t1->ty == Tstruct)
             {
                 // Do bit compare of struct's
                 elem *es1 = toElem(ee->e1, irs);
@@ -2265,7 +2270,12 @@ elem *toElem(Expression *e, IRState *irs)
             //printf("IdentityExp::toElem() %s\n", toChars());
 
             elem *e;
-            if (t1->ty == Tstruct || t1->isfloating())
+            if (t1->ty == Tstruct && ((TypeStruct *)t1)->sym->fields.dim == 0)
+            {
+                // we can skip the compare if the structs are empty
+                e = el_long(TYbool, ie->op == TOKidentity);
+            }
+            else if (t1->ty == Tstruct || t1->isfloating())
             {
                 // Do bit compare of struct's
                 elem *es1 = toElem(ie->e1, irs);

diff --git a/test/runnable/xtest46.d b/test/runnable/xtest46.d
@@ -5372,6 +5372,27 @@ void test2856()
     B[1];                   // Okay
 }
 
+/***************************************************/
+
+void test13947()
+{
+    struct S {}
+    static assert(S.sizeof == 1);
+
+    S a;
+    S b;
+    *cast(ubyte*)&a = 1;
+    *cast(ubyte*)&b = 2;
+    assert(a == b);
+    assert(a is b);
+    assert(!(a != b));
+    assert(!(a !is b));
+    static assert(S() == S());
+    static assert(S() is S());
+    static assert(!(S() != S()));
+    static assert(!(S() !is S()));
+}
+
 /***************************************************/
 // 3091
 
@@ -7507,6 +7528,7 @@ int main()
     test9538();
     test9700();
     test9834();
+    test13947();
     test9883();
     test10091();
     test9130();