autoconf: Backslash-Newline-Empty
1
1 12.4 Backslash-Newline Before Empty Lines
1 =========================================
1
1 A bug in Bash 2.03 can cause problems if a Make rule contains a
1 backslash-newline followed by line that expands to nothing. For
1 example, on Solaris 8:
1
1 SHELL = /bin/bash
1 EMPTY =
1 foo:
1 touch foo \
1 $(EMPTY)
1
1 executes
1
1 /bin/bash -c 'touch foo \
1 '
1
1 which fails with a syntax error, due to the Bash bug. To avoid this
1 problem, avoid nullable macros in the last line of a multiline command.
1
1 On some versions of HP-UX, `make' reads multiple newlines following
1 a backslash, continuing to the next non-empty line. For example,
1
1 FOO = one \
1
1 BAR = two
1
1 test:
1 : FOO is "$(FOO)"
1 : BAR is "$(BAR)"
1
1 shows `FOO' equal to `one BAR = two'. Other implementations sensibly
1 let a backslash continue only to the immediately following line.
1