fix Issue 15399 - unaligned pointers are not @safe

src/expression.d

@@ -112,6 +112,42 @@ bool checkOverlappedPointer(Scope* sc, Expression e, string msg)
     return false;
 }
 
+/*************************************************************
+ * Check if e is a DotVarExp representing a misaligned pointer.
+ * Print error if misaligned pointer and in @safe.
+ * Params:
+ *      sc = scope
+ *      e = expression to check
+ *      msg = error message string
+ * Returns:
+ *      true if error
+ */
+
+bool checkMisalignedPointer(Scope* sc, Expression e, string msg)
+{
+    if (e.op != TOKdotvar)
+        return false;
+    DotVarExp dve = cast(DotVarExp)e;
+    if (VarDeclaration v = dve.var.isVarDeclaration())
+    {
+        if (v.isField() && !sc.intypeof && sc.func &&
+            (v.type.hasPointers() && v.type.toBasetype().ty != Tstruct))
+        {
+            if (auto ad = v.toParent2().isAggregateDeclaration())
+            {
+                if ((ad.type.alignment() < Target.ptrsize ||
+                     (v.offset & (Target.ptrsize - 1))) &&
+                    sc.func.setUnsafe())
+                {
+                    e.error(msg.ptr, ad.toChars(), v.toChars());
+                    return true;
+                }
+            }
+        }
+    }
+    return false;
+}
+
 /*************************************************************
  * Given var, we need to get the
  * right 'this' pointer if var is in an outer class, but our
@@ -1686,6 +1722,10 @@ extern (C++) bool functionParameters(Loc loc, Scope* sc, TypeFunction tf, Type t
             if (p.storageClass & STCref)
             {
                 arg = arg.toLvalue(sc, arg);
+
+                // Look for mutable misaligned pointer in @safe mode
+                if (arg.type.isMutable())
+                    err |= checkMisalignedPointer(sc, arg, "'ref' of misaligned pointer in field %s.%s is not @safe");
             }
             else if (p.storageClass & STCout)
             {
@@ -1696,7 +1736,11 @@ extern (C++) bool functionParameters(Loc loc, Scope* sc, TypeFunction tf, Type t
                     err = true;
                 }
                 else
+                {
+                    // Look for misaligned pointer in @safe mode
+                    err |= checkMisalignedPointer(sc, arg, "'out' of misaligned pointer in field %s.%s is not @safe");
                     err |= checkDefCtor(arg.loc, t); // t must be default constructible
+                }
                 arg = arg.toLvalue(sc, arg);
             }
             else if (p.storageClass & STClazy)
@@ -9058,6 +9102,11 @@ extern (C++) final class DotVarExp : UnaExp
             printf("e1->type = %s\n", e1.type.toChars());
             printf("var->type = %s\n", var.type.toChars());
         }
+
+        // Look for misaligned pointer in @safe mode
+        if (checkMisalignedPointer(sc, this, "writing to misaligned pointer in field %s.%s is not @safe"))
+            return new ErrorExp();
+
         return Expression.modifiableLvalue(sc, e);
     }
 
@@ -10548,6 +10597,10 @@ extern (C++) final class AddrExp : UnaExp
                 e = e.semantic(sc);
                 return e;
             }
+
+            // Look for misaligned pointer in @safe mode
+            if (checkMisalignedPointer(sc, dve, "taking address of misaligned pointer in field %s.%s is not @safe"))
+                return new ErrorExp();
         }
         else if (e1.op == TOKvar)
         {
@@ -11945,6 +11998,16 @@ extern (C++) final class IntervalExp : Expression
         return this;
     }
 
+    override Expression modifiableLvalue(Scope* sc, Expression e)
+    {
+        if (sc.func.setUnsafe())
+        {
+            error("cannot modify delegate pointer in @safe code %s", toChars());
+            return new ErrorExp();
+        }
+        return Expression.modifiableLvalue(sc, e);
+    }
+
     override void accept(Visitor v)
     {
         v.visit(this);

test/fail_compilation/test15399.d

@@ -0,0 +1,46 @@
+/* https://issues.dlang.org/show_bug.cgi?id=15399
+---
+fail_compilation/test15399.d(31): Error: writing to misaligned pointer in field S1.ptr is not @safe
+fail_compilation/test15399.d(32): Error: writing to misaligned pointer in field S2.ptr is not @safe
+fail_compilation/test15399.d(33): Error: taking address of misaligned pointer in field S1.ptr is not @safe
+fail_compilation/test15399.d(34): Error: taking address of misaligned pointer in field S2.ptr is not @safe
+fail_compilation/test15399.d(35): Error: 'ref' of misaligned pointer in field S1.ptr is not @safe
+fail_compilation/test15399.d(36): Error: 'ref' of misaligned pointer in field S2.ptr is not @safe
+fail_compilation/test15399.d(37): Error: 'out' of misaligned pointer in field S1.ptr is not @safe
+fail_compilation/test15399.d(38): Error: 'out' of misaligned pointer in field S2.ptr is not @safe
+---
+*/
+
+struct S1
+{
+        char c;
+    align (1)
+        int* ptr;
+}
+
+align (1)
+struct S2
+{
+    int* ptr;
+}
+
+@safe void test(S1* s1, S2* s2)
+{
+    int* p = s1.ptr;
+    p = s2.ptr;
+    s1.ptr = null;
+    s2.ptr = null;
+    int** pp = &s1.ptr;
+    pp = &s2.ptr;
+    bar(s1.ptr);
+    bar(s2.ptr);
+    sinister(s1.ptr);
+    sinister(s2.ptr);
+    cbar(s1.ptr);
+    cbar(s2.ptr);
+}
+
+@safe void bar(ref int*);
+@safe void cbar(ref const int*);
+@safe void sinister(out int*);
+

test/runnable/testsafe.d

@@ -156,9 +156,9 @@ void safeunions()   // improved for issue 11510
     su1.a = 7, su1.b = 8, su1.c = null;
     su2.a = 7, su2.b = 8, su2.c = 9;
     uu1.a = 7,            uu1.c = null;
-    uu2.a = 7; uu2.b = 8, uu2.c = null;
+    uu2.a = 7; uu2.b = 8, //uu2.c = null;
     uu3.a = 7;            uu3.c = null;
-    uu4.a = 7; uu4.b = 8, uu4.c = null;
+    uu4.a = 7; uu4.b = 8, //uu4.c = null;
     uu5.x.a = 7; uu5.x.b = 8, uu5.x.c = 9;
     uud.a.a.a.a = null, uud.a.a.a.b = null;