string-util: use size_t for strjoina macro (#6914)

`strlen` returns a `size_t` and `alloca` expects a `size_t`.

diff --git a/src/basic/string-util.h b/src/basic/string-util.h
index a28ef9c4f777fa54886317281f42a3c0e4f195e4..19c8d8bb3ec3a8475380b0c18d76b75825f732f0 100644 (file)
--- a/src/basic/string-util.h
+++ b/src/basic/string-util.h
@@ -124,7 +124,7 @@ char *strjoin_real(const char *x, ...) _sentinel_;
         ({                                                              \
                 const char *_appendees_[] = { a, __VA_ARGS__ };         \
                 char *_d_, *_p_;                                        \
-                int _len_ = 0;                                          \
+                size_t _len_ = 0;                                          \
                 unsigned _i_;                                           \
                 for (_i_ = 0; _i_ < ELEMENTSOF(_appendees_) && _appendees_[_i_]; _i_++) \
                         _len_ += strlen(_appendees_[_i_]);              \