===================================================================
@@ -1836,7 +1836,22 @@ num_binary_op (cpp_reader *pfile, cpp_num lhs, cpp
/* Arithmetic. */
case CPP_MINUS:
- rhs = num_negate (rhs, precision);
+ result.low = lhs.low - rhs.low;
+ result.high = lhs.high - rhs.high;
+ if (result.low > lhs.low)
+ result.high--;
+ result.unsignedp = lhs.unsignedp || rhs.unsignedp;
+ result.overflow = false;
+
+ result = num_trim (result, precision);
+ if (!result.unsignedp)
+ {
+ bool lhsp = num_positive (lhs, precision);
+ result.overflow = (lhsp != num_positive (rhs, precision)
+ && lhsp != num_positive (result, precision));
+ }
+ return result;
+
case CPP_PLUS:
result.low = lhs.low + rhs.low;
result.high = lhs.high + rhs.high;
===================================================================
@@ -0,0 +1,44 @@
+/* Test overflow in preprocessor arithmetic. PR 55715. */
+/* { dg-do preprocess } */
+/* { dg-options "-std=c99" } */
+
+#include <stdint.h>
+
+#if -1 - INTMAX_MIN
+#endif
+
+#if 0 - INTMAX_MIN /* { dg-warning "overflow" } */
+#endif
+
+#if 1 * INTMAX_MIN
+#endif
+
+#if -1 * INTMAX_MIN /* { dg-warning "overflow" } */
+#endif
+
+#if 0 * INTMAX_MIN
+#endif
+
+#if -INTMAX_MIN /* { dg-warning "overflow" } */
+#endif
+
+#if +INTMAX_MIN
+#endif
+
+#if INTMAX_MIN / 1
+#endif
+
+#if INTMAX_MIN / -1 /* { dg-warning "overflow" } */
+#endif
+
+#if UINTMAX_MAX * UINTMAX_MAX
+#endif
+
+#if UINTMAX_MAX / -1
+#endif
+
+#if UINTMAX_MAX + INTMAX_MAX
+#endif
+
+#if UINTMAX_MAX - INTMAX_MIN
+#endif