Fix issue with unifying void returns.

resources/testfragments/demo1.c3

@@ -0,0 +1,152 @@
+module demo1;
+
+// Use C functions directly.
+extern func int printf(char *, ...);
+extern func void puts(char *);
+
+struct Foo
+{
+    int a;
+    int b;
+}
+
+func Foo createFoo(int a, int b = 10)
+{
+    // Compound initializer
+    return Foo({a, b});
+}
+
+struct Bar
+{
+    int x;
+    int y;
+}
+
+
+func void testStruct()
+{
+    // Default arguments
+    Foo foo = createFoo(100);
+    printf("Foo a:%d b:%d\n", foo.a, foo.b);
+
+    // No need to write foo = (Foo){ 11, 22 }
+    // unlike C
+    foo = { 11, 12 };
+
+    // Named arguments
+    foo = createFoo(.b = 13, .a = 14);
+    printf("Foo a:%d b:%d\n", foo.a, foo.b);
+
+    // Structural copy
+    Bar bar = (Bar)(foo);
+    printf("Bar x:%d y:%d\n", bar.x, bar.y);
+
+    // Type functions
+    printf("Mult: %d\n", foo.mult());
+    printf("Add: %d\n", bar.add());
+
+}
+
+func int Bar.add(Bar* b)
+{
+    return b.x + b.y;
+}
+
+func int Foo.mult(Foo* f)
+{
+    return f.a * f.b;
+}
+
+func void printArray(int[] array)
+{
+    printf("[");
+    foreach (i, a : array)
+    {
+        if (i != 0) printf(", ");
+        printf("%d", a);
+    }
+    printf("]\n");
+}
+
+
+func void testArrays()
+{
+    int[5] x = { [0] = 100, [1..2] = 4 };
+    puts("Testing arrays---");
+    foreach (a : x)
+    {
+        printf("%d\n", a);
+    }
+    puts("Arrays with index---");
+    foreach (i, a : x)
+    {
+        printf("index[%d]: %d\n", i, a);
+    }
+    puts("Mutating arrays---");
+    foreach (i, int* &a : x) { *a += (int)(i); }
+    foreach (i, a : x)
+    {
+        printf("index[%d]: %d\n", i, a);
+    }
+    puts("Without & there is no change---");
+    foreach (i, a : x) { a += (int)(i); }
+    foreach (i, a : x)
+    {
+        printf("index[%d]: %d\n", i, a);
+    }
+    printf("Length is a compile time value: %d\n", x.len);
+    puts("Getting a slice---");
+    int[] y = x[1..3];
+    foreach (i, a : y)
+    {
+        printf("index[%d]: %d\n", i, a);
+    }
+    printf("Length is a runtime value: %d\n", y.len());
+    puts("Getting a slice from the beginning to an offset of the end---");
+    y = x[..^2]; // Same as x[0..^2]
+    foreach (i, a : y)
+    {
+        printf("index[%d]: %d\n", i, a);
+    }
+    puts("Printing arrays---");
+    printArray(&x);
+    printArray(y);
+    printArray(x[1..]);
+    puts("Array to pointer to subarray---");
+    int* z = &x;
+    printArray(z[0..2]);
+    printf("Pointer to array: %p\nPointer to slice: %p\nPointer to first element of slice: %p\n", z, &y, &y[0]);
+}
+
+func void testExpressionBlocks()
+{
+    int x = {|
+        int j = 0;
+        for (int i = 0; i < 10; i++)
+        {
+           j += i + j;
+           if (j > 10) return j;
+        }
+        return 0;
+    |};
+    printf("x: %d\n", x);
+    {|
+       for (int i = 0; i < 10; i++)
+       {
+         printf("%d\n", i);
+         if (i && i % 4 == 0) return;
+       }
+       puts("Reached end");
+    |};
+    if ({| for (int i = 0; i < 10; i++) printf("--%d\n", i); puts("Done!"); return true; |})
+    {
+        puts("In if");
+    }
+}
+
+func void main()
+{
+    testStruct();
+    testArrays();
+    testExpressionBlocks();
+}

src/compiler/sema_expr.c

@@ -1071,7 +1071,7 @@ static inline Type *unify_returns(Context *context, Type *to)
 			SEMA_PREV(context->returns[i - 1], "Previous return was here.");
 			return NULL;
 		}
-		if (to)
+		if (to != type_void)
 		{
 			if (current_expr_was_void)
 			{