Merge pull request #8941 from dlang/thewilsonator-patch-3

 Fix issue 16976 - Do not convert blindly the size of an iterable
merged-on-behalf-of: Nicholas Wilson <thewilsonator@users.noreply.github.com>

src/dmd/statementsem.d

@@ -1229,6 +1229,11 @@ private extern (C++) final class StatementSemanticVisitor : Visitor
 
                     if (dim == 2 && i == 0)
                     {
+                        if (!p.type.isintegral())
+                        {
+                            fs.error("foreach: key cannot be of non-integral type `%s`", p.type.toChars());
+                            goto case Terror;
+                        }
                         var = new VarDeclaration(loc, p.type.mutableOf(), Identifier.generateId("__key"), null);
                         var.storage_class |= STC.temp | STC.foreach_;
                         if (var.storage_class & (STC.ref_ | STC.out_))
@@ -1256,6 +1261,11 @@ private extern (C++) final class StatementSemanticVisitor : Visitor
                             }
                             fs.key.range = new IntRange(SignExtendedNumber(0), dimrange.imax);
                         }
+                        else if (!Type.tsize_t.implicitConvTo(var.type))
+                        {
+                            fs.deprecation("foreach: loop index implicitly converted from `size_t` to `%s`",
+                                           fs.key.type.toChars());
+                        }
                     }
                     else
                     {
@@ -1323,6 +1333,10 @@ private extern (C++) final class StatementSemanticVisitor : Visitor
                     fs.key = new VarDeclaration(loc, Type.tsize_t, idkey, null);
                     fs.key.storage_class |= STC.temp;
                 }
+                else if (fs.key.type.ty != Tsize_t)
+                {
+                    tmp_length = new CastExp(loc, tmp_length, fs.key.type);
+                }
                 if (fs.op == TOK.foreach_reverse_)
                     fs.key._init = new ExpInitializer(loc, tmp_length);
                 else

test/compilable/b16976.d

@@ -0,0 +1,23 @@
+/* REQUIRED_ARGS: -m64
+TEST_OUTPUT:
+---
+compilable/b16976.d(15): Deprecation: foreach: loop index implicitly converted from `size_t` to `int`
+compilable/b16976.d(16): Deprecation: foreach: loop index implicitly converted from `size_t` to `int`
+compilable/b16976.d(17): Deprecation: foreach: loop index implicitly converted from `size_t` to `char`
+compilable/b16976.d(18): Deprecation: foreach: loop index implicitly converted from `size_t` to `char`
+---
+*/
+void main()
+{
+    int[]  dyn = [1,2,3,4,5];
+    int[5] sta = [1,2,3,4,5];
+
+    foreach(int i, v; dyn) { }
+    foreach_reverse(int i, v; dyn) { }
+    foreach(char i, v; dyn) { }
+    foreach_reverse(char i, v; dyn) { }
+    foreach(int i, v; sta) { }
+    foreach_reverse(int i, v; sta) { }
+    foreach(char i, v; sta) { }
+    foreach_reverse(char i, v; sta) { }
+}

test/fail_compilation/diag16976.d

@@ -0,0 +1,18 @@
+/* TEST_OUTPUT:
+---
+fail_compilation/diag16976.d(14): Error: foreach: key cannot be of non-integral type `float`
+fail_compilation/diag16976.d(15): Error: foreach: key cannot be of non-integral type `float`
+fail_compilation/diag16976.d(16): Error: foreach: key cannot be of non-integral type `float`
+fail_compilation/diag16976.d(17): Error: foreach: key cannot be of non-integral type `float`
+---
+*/
+
+void main()
+{
+    int[]  dyn = [1,2,3,4,5];
+    int[5] sta = [1,2,3,4,5];
+    foreach(float f, i; dyn) {}
+    foreach(float f, i; sta) {}
+    foreach_reverse(float f, i; dyn) {}
+    foreach_reverse(float f, i; sta) {}
+}

test/fail_compilation/fail110.d

@@ -14,6 +14,6 @@ void main()
     int i;
     int[] a;
     foreach (i; a) {}
-    foreach (int i, n; a) {}
+    foreach (size_t i, n; a) {}
     for (int i;;) {}
 }