// RUN: %check_clang_tidy %s bugprone-macro-repeated-side-effects %t #define badA(x,y) ((x)+((x)+(y))+(y)) void bad(int ret, int a, int b) { ret = badA(a++, b); // CHECK-NOTES: :[[@LINE-1]]:14: warning: side effects in the 1st macro argument 'x' are repeated in macro expansion [bugprone-macro-repeated-side-effects] // CHECK-NOTES: :[[@LINE-4]]:9: note: macro 'badA' defined here ret = badA(++a, b); // CHECK-NOTES: :[[@LINE-1]]:14: warning: side effects in the 1st macro argument 'x' // CHECK-NOTES: :[[@LINE-7]]:9: note: macro 'badA' defined here ret = badA(a--, b); // CHECK-NOTES: :[[@LINE-1]]:14: warning: side effects in the 1st macro argument 'x' // CHECK-NOTES: :[[@LINE-10]]:9: note: macro 'badA' defined here ret = badA(--a, b); // CHECK-NOTES: :[[@LINE-1]]:14: warning: side effects in the 1st macro argument 'x' // CHECK-NOTES: :[[@LINE-13]]:9: note: macro 'badA' defined here ret = badA(a, b++); // CHECK-NOTES: :[[@LINE-1]]:17: warning: side effects in the 2nd macro argument 'y' // CHECK-NOTES: :[[@LINE-16]]:9: note: macro 'badA' defined here ret = badA(a, ++b); // CHECK-NOTES: :[[@LINE-1]]:17: warning: side effects in the 2nd macro argument 'y' // CHECK-NOTES: :[[@LINE-19]]:9: note: macro 'badA' defined here ret = badA(a, b--); // CHECK-NOTES: :[[@LINE-1]]:17: warning: side effects in the 2nd macro argument 'y' // CHECK-NOTES: :[[@LINE-22]]:9: note: macro 'badA' defined here ret = badA(a, --b); // CHECK-NOTES: :[[@LINE-1]]:17: warning: side effects in the 2nd macro argument 'y' // CHECK-NOTES: :[[@LINE-25]]:9: note: macro 'badA' defined here } #define MIN(A,B) ((A) < (B) ? (A) : (B)) // single ?: #define LIMIT(X,A,B) ((X) < (A) ? (A) : ((X) > (B) ? (B) : (X))) // two ?: void question(int x) { MIN(x++, 12); // CHECK-NOTES: :[[@LINE-1]]:7: warning: side effects in the 1st macro argument 'A' // CHECK-NOTES: :[[@LINE-5]]:9: note: macro 'MIN' defined here MIN(34, x++); // CHECK-NOTES: :[[@LINE-1]]:11: warning: side effects in the 2nd macro argument 'B' // CHECK-NOTES: :[[@LINE-8]]:9: note: macro 'MIN' defined here LIMIT(x++, 0, 100); // CHECK-NOTES: :[[@LINE-1]]:9: warning: side effects in the 1st macro argument 'X' // CHECK-NOTES: :[[@LINE-10]]:9: note: macro 'LIMIT' defined here LIMIT(20, x++, 100); // CHECK-NOTES: :[[@LINE-1]]:13: warning: side effects in the 2nd macro argument 'A' // CHECK-NOTES: :[[@LINE-13]]:9: note: macro 'LIMIT' defined here LIMIT(20, 0, x++); // CHECK-NOTES: :[[@LINE-1]]:16: warning: side effects in the 3rd macro argument 'B' // CHECK-NOTES: :[[@LINE-16]]:9: note: macro 'LIMIT' defined here } // False positive: Repeated side effects is intentional. // It is hard to know when it's done by intention so right now we warn. #define UNROLL(A) {A A} void fp1(int i) { UNROLL({ i++; }); // CHECK-NOTES: :[[@LINE-1]]:10: warning: side effects in the 1st macro argument 'A' // CHECK-NOTES: :[[@LINE-4]]:9: note: macro 'UNROLL' defined here } // Do not produce a false positive on a strchr() macro. Explanation; Currently the '?' // triggers the test to bail out, because it cannot evaluate __builtin_constant_p(c). # define strchrs(s, c) \ (__extension__ (__builtin_constant_p (c) && !__builtin_constant_p (s) \ && (c) == '\0' \ ? (char *) __rawmemchr (s, c) \ : __builtin_strchr (s, c))) char* __rawmemchr(char* a, char b) { return a; } void pass(char* pstr, char ch) { strchrs(pstr, ch++); // No error. } // Check large arguments (t=20, u=21). #define largeA(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, x, y, z) \ ((a) + (a) + (b) + (b) + (c) + (c) + (d) + (d) + (e) + (e) + (f) + (f) + (g) + (g) + \ (h) + (h) + (i) + (i) + (j) + (j) + (k) + (k) + (l) + (l) + (m) + (m) + (n) + (n) + \ (o) + (o) + (p) + (p) + (q) + (q) + (r) + (r) + (s) + (s) + (t) + (t) + (u) + (u) + \ (v) + (v) + (x) + (x) + (y) + (y) + (z) + (z)) void large(int a) { largeA(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, a++, 0, 0, 0, 0, 0, 0); // CHECK-NOTES: :[[@LINE-1]]:64: warning: side effects in the 19th macro argument 's' // CHECK-NOTES: :[[@LINE-8]]:9: note: macro 'largeA' defined here largeA(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, a++, 0, 0, 0, 0, 0); // CHECK-NOTES: :[[@LINE-1]]:67: warning: side effects in the 20th macro argument 't' // CHECK-NOTES: :[[@LINE-11]]:9: note: macro 'largeA' defined here largeA(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, a++, 0, 0, 0, 0); // CHECK-NOTES: :[[@LINE-1]]:70: warning: side effects in the 21st macro argument 'u' // CHECK-NOTES: :[[@LINE-14]]:9: note: macro 'largeA' defined here } // Passing macro argument as argument to __builtin_constant_p and macros. #define builtinbad(x) (__builtin_constant_p(x) + (x) + (x)) #define builtingood1(x) (__builtin_constant_p(x) + (x)) #define builtingood2(x) ((__builtin_constant_p(x) && (x)) || (x)) #define macrobad(x) (builtingood1(x) + (x) + (x)) #define macrogood(x) (builtingood1(x) + (x)) void builtins(int ret, int a) { ret += builtinbad(a++); // CHECK-NOTES: :[[@LINE-1]]:21: warning: side effects in the 1st macro argument 'x' // CHECK-NOTES: :[[@LINE-8]]:9: note: macro 'builtinbad' defined here ret += builtingood1(a++); ret += builtingood2(a++); ret += macrobad(a++); // CHECK-NOTES: :[[@LINE-1]]:19: warning: side effects in the 1st macro argument 'x' // CHECK-NOTES: :[[@LINE-12]]:9: note: macro 'macrobad' defined here ret += macrogood(a++); } // Bail out for conditionals. #define condB(x,y) if(x) {x=y;} else {x=y + 1;} void conditionals(int a, int b) { condB(a, b++); } void log(const char *s, int v); #define LOG(val) log(#val, (val)) void test_log(int a) { LOG(a++); }