81 lines
2.3 KiB
Makefile
81 lines
2.3 KiB
Makefile
# $NetBSD: comment.mk,v 1.5 2022/05/08 06:51:27 rillig Exp $
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#
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# Demonstrate how comments are written in makefiles.
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# This is a comment.
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#\
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This is a multiline comment.
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# Another multiline comment \
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that \
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goes \
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on and on.
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# Comments can be indented with spaces, but that is rather unusual.
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# Comments can be indented with a tab.
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# Since parse.c 1.127 from 2007-01-01, these are not shell commands,
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# they are just makefile comments. Before that commit, these comments
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# triggered the error message "Unassociated shell command".
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.if 1 # There can be comments after conditions.
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.endif # And after the closing directive.
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VAR= # This comment makes the variable value empty.
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# ParseRawLine removes any whitespace before the
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# comment.
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.if ${VAR} != ""
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. error
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.endif
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# The comment does not need to start at the beginning of a word (as in the
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# shell), it can start anywhere.
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VAR=# defined but empty
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# The space before the comment is always trimmed.
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VAR= value
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.if ${VAR} != "value"
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. error
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.endif
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# This comment ends with 2 backslashes. An even number of backslashes does
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# not count as a line continuation, therefore the variable assignment that
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# follows is actively interpreted. \\
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VAR= not part of the comment
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.if ${VAR} != "not part of the comment"
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. error
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.endif
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# To escape a comment sign, precede it with a backslash.
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VAR= \# # Both in the assignment.
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.if ${VAR} != "\#" # And in the comparison.
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. error
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.endif
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# Since 2012-03-24 the variable modifier :[#] does not need to be escaped.
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# To keep the parsing code simple, any "[#" does not start a comment, even
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# outside of a variable expression.
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WORDS= ${VAR:[#]} [#
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.if ${WORDS} != "1 [#"
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. error
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.endif
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# An odd number of backslashes makes a line continuation, \\\
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no matter if it is 3 or 5 \\\\\
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or 9 backslashes. \\\\\\\\\
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This is the last line of the comment.
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VAR= no comment anymore
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.if ${VAR} != "no comment anymore"
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. error
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.endif
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all:
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# In the commands associated with a target, the '#' does not start a makefile
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# comment. The '#' is just passed to the shell, like any ordinary character.
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echo This is a shell comment: # comment
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# If the '#' were to start a makefile comment, the following shell command
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# would have unbalanced quotes.
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echo This is not a shell comment: '# comment'
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@echo A shell comment can#not start in the middle of a word.
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