RHS primary integer promotion must happen after loading the primary, not before. See: #2060

src/cc65/expr.c

@@ -3090,9 +3090,10 @@ static void parseadd (ExprDesc* Expr, int DoArrayRef)
                 Expr->Type = Expr2.Type;
             } else if (!DoArrayRef && IsClassInt (lhst) && IsClassInt (rhst)) {
                 /* Integer addition */
-                flags = typeadjust (Expr, &Expr2, 0);
                 /* Load rhs into the primary */
                 LoadExpr (CF_NONE, &Expr2);
+                /* Adjust rhs primary if needed  */
+                flags = typeadjust (Expr, &Expr2, 0);
             } else {
                 /* OOPS */
                 AddDone = -1;

test/val/bug2060.c

@@ -0,0 +1,56 @@
+/* Test of bug: https://github.com/cc65/cc65/issues/2060 */
+
+#include <stdio.h>
+
+#define W 320
+
+unsigned long test1(unsigned char* p, unsigned long n)
+{
+    (void)p;
+    return n;
+}
+
+unsigned long test0(unsigned char* p, int x, int y, unsigned char b)
+{
+    (void)b;
+    return test1(p, (long)y * W + x);
+}
+
+#define TEST(ta,tb) \
+    expect = (long)tb * W + ta; \
+    result = test0(p,ta,tb,0x56); \
+    printf("%4d * %3d + %4d = %08lx",tb,W,ta,result); \
+    if (expect != result) { printf(" expected: %08lx\n",expect); ++fail; } \
+    else printf("\n");
+
+int main(void)
+{
+    unsigned char* p = (unsigned char*)0x1234;
+    unsigned long expect, result;
+    int fail = 0;
+
+    TEST(1,3);
+    TEST(50,60);
+    TEST(99,88);
+    TEST(128,102);
+    TEST(129,102);
+    TEST(320,102);
+    /* Bug 2060 indicated failure when y > 102.
+       Because: (y * 320) > 32767
+       The promotion of x from int to long had an incorrect high word,
+       because it was done before loading x into AX, rather than after.
+    */
+    TEST(0,103);
+    TEST(150,170);
+    TEST(300,180);
+    /* x < 0 also fails because its high word sign extend is incorrect. */
+    TEST(-100,50);
+    TEST(-49,99);
+    TEST(-300,-180);
+    /* This passed despite the bug, because y * 320 coincidentally had the
+       same high word.
+    */
+    TEST(-1,-1);
+
+    return fail;
+}