pkg-config.1 in current git (commit c53385b5) says: Similar to PKG_CHECK_MODULES, make sure that the first instance of this or PKG_CHECK_MODULES is called, or make sure to call PKG_CHECK_EXISTS manually. In the last line of that, should it say "PKG_PROG_PKG_CONFIG" rather than "PKG_CHECK_EXISTS"? In the case of PKG_CHECK_MODULES, it says: Note that if there is a possibility the first call to PKG_CHECK_MODULES might not happen, you should be sure to include an explicit call to PKG_PROG_PKG_CONFIG in your configure.ac. i.e. if the first call to PKG_CHECK_MODULES might not happen, then PKG_PROG_PKG_CONFIG should be called. Presumably the same is meant for PKG_CHECK_EXISTS?
Fixed in commit 99ef6fd. Thanks for the report.
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