diff options
| -rw-r--r-- | make.texinfo | 22 |
1 files changed, 14 insertions, 8 deletions
diff --git a/make.texinfo b/make.texinfo index 83babc8..46c50e8 100644 --- a/make.texinfo +++ b/make.texinfo @@ -9,7 +9,7 @@ @set EDITION 0.44 @set VERSION 3.69 Beta -@set UPDATED 6 September 1993 +@set UPDATED 17 September 1993 @set UPDATE-MONTH September 1993 @c finalout @@ -1558,10 +1558,11 @@ expansion happens in the rule for @file{foo}, so that each @emph{existing} @samp{.o} file becomes a dependency of @file{foo} and will be recompiled if necessary. -But what if you delete all the @samp{.o} files? Then @samp{*.o} will -expand into @emph{nothing}. The target @file{foo} will have no -dependencies and would be remade by linking no object files. This is not -what you want! +But what if you delete all the @samp{.o} files? When a wildcard matches +no files, it is left as it is, so then @file{foo} will depend on the +oddly-named file @file{*.o}. Since so such file is likely to exist, +@code{make} will give you an error saying it cannot figure out how to +make @file{*.o}. This is not what you want! Actually it is possible to obtain the desired result with wildcard expansion, but you need more sophisticated techniques, including the @@ -1583,12 +1584,17 @@ arguments of a function. If you want to do wildcard expansion in such places, you need to use the @code{wildcard} function, like this: @example -$(wildcard @var{pattern}) +$(wildcard @var{pattern}@dots{}) @end example @noindent -This string, used anywhere in a makefile, is replaced by a space-separated -list of names of existing files that match the pattern @var{pattern}. +This string, used anywhere in a makefile, is replaced by a +space-separated list of names of existing files that match one of the +given file name patterns. If no existing file name matches a pattern, +then that pattern is omitted from the output of the @code{wildcard} +function. Note that this is different from how unmatched wildcards +behave in rules, where they are used verbatim rather than ignored +(@pxref{Wildcard Pitfall}). One use of the @code{wildcard} function is to get a list of all the C source files in a directory, like this: |