make: Implicit/Search
4.5.5 Directory Search and Implicit Rules
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The search through the directories specified in 'VPATH' or with 'vpath'
also happens during consideration of implicit rules (
Using
Implicit Rules Implicit Rules.).
For example, when a file 'foo.o' has no explicit rule, 'make'
considers implicit rules, such as the built-in rule to compile 'foo.c'
if that file exists. If such a file is lacking in the current
directory, the appropriate directories are searched for it. If 'foo.c'
exists (or is mentioned in the makefile) in any of the directories, the
implicit rule for C compilation is applied.
The recipes of implicit rules normally use automatic variables as a
matter of necessity; consequently they will use the file names found by
directory search with no extra effort.
Info Catalog
make: Recipes/Search
make: Directory Search
make: Libraries/Search