diff options
Diffstat (limited to 'NEWS')
| -rw-r--r-- | NEWS | 24 |
1 files changed, 15 insertions, 9 deletions
@@ -18,15 +18,21 @@ Version 3.81beta3 * WARNING: Backward-incompatibility! GNU make now implements a generic "second expansion" feature on the - prerequisites of both explicit and implicit (pattern) rules. After - all rules have been parsed the prerequisites are expanded again, this - time with all the automatic variables in scope. This means that in - addition to using standard SysV $$@ in prerequisites lists, you can - also use complex functions such as $$(notdir $$@) etc. This behavior - applies to implicit rules, as well, where the second expansion occurs - after the rule is matched. However, this means that you need to - double-quote any "$" in your filenames; instead of "foo: boo$$bar" you - now must write "foo: foo$$$$bar". + prerequisites of both explicit and implicit (pattern) rules. In order + to enable this feature, the special target '.SECONDEXPANSION' must be + defined before the first target which takes advantage of it. If this + feature is enabled then after all rules have been parsed the + prerequisites are expanded again, this time with all the automatic + variables in scope. This means that in addition to using standard + SysV $$@ in prerequisites lists, you can also use complex functions + such as $$(notdir $$@) etc. This behavior applies to implicit rules, + as well, where the second expansion occurs when the rule is matched. + However, this means that you need to double-quote any "$" in your + filenames; instead of "foo: boo$$bar" you now must write "foo: + foo$$$$bar". Note that the SysV $$@ etc. feature, which used to be + available by default, is now ONLY available when the .SECONDEXPANSION + target is defined. If your makefiles take advantage of this SysV + feature you will need to update them. * WARNING: Backward-incompatibility! In order to comply with POSIX, the way in which GNU make processes |