foo.cc: In function ‘void dfs(int, int)’:
foo.cc:14:18: warning: this ‘for’ clause does not guard... [-Wmisleading-indentation]
   14 | #define R(i,a,b) for(int i=(a),I=(b);i<I;i++)
      |                  ^~~
foo.cc:47:9: note: in expansion of macro ‘R’
   47 |         R(i,0,n) vis[i]=false; match(s)?dfs(J,s+1):void();
      |         ^
foo.cc:47:32: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the ‘for’
   47 |         R(i,0,n) vis[i]=false; match(s)?dfs(J,s+1):void();
      |                                ^~~~~