What is the difference between AM_LDFLAGS and LDFLAGS

I want to know what is the difference between AM_LDFLAGS and LDFLAGS as I ran into the error

error: AM_LDFLAGS must be set with '=' before using '+='

      

when i used AM_LDFLAGS in foreach loop my makefile code as below:

program_INCLUDE_DIRS := /usr/bin/PR__bin

program_LIBRARY_DIRS := /usr/lib/PR__lib

CFLAGS += $(foreach includedir,$(program_INCLUDE_DIRS),-I$(includedir))

AM_LDFLAGS += $(foreach librarydir,$(program_LIBRARY_DIRS),-L$(librarydir))

      

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2 answers


If this error complains about what it says it is complaining about (and I'm not at all sure why it should / should be), I would think the solution would be as simple as simply adding

AM_LDFLAGS =

      

as the line above the foreach loop that uses +=

.



From 8.7 Variables used when building a program

the GNU Automake manual section :

AM_LDFLAGS

This is a variable that the author of Makefile.am can use to pass additional linker flags. In some situations this is not used, it is preferable for each executable (or for the library) _LDFLAGS.

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_ I want to know what is the difference between AM_LDFLAGS and LDFLAGS _

LDFLAGS

is a variable inherited from Autoconf AM_LDFLAGS

is a variable defined by automake.

According to the automania help page ,

This is a variable that the author Makefile.am

can use to add additional linker flags. In some situations this is not used, preferably for an executable (or for a library) _LDFLAGS

.

However, repeating the error, as per the information provided here , it looks like a problem using a variable. Automake expects a variable to be set to some value before it can be added.



The correct way to address this question would be the same as the one mentioned in another answer provided by Ethan Reisner, just set AM_LDFLAGS

explicitly before the loop, something like

AM_LDFLAGS =     // which "sets" the AM_LDFLAGS

      

and then do

AM_LDFLAGS += $(foreach librarydir,$(program_LIBRARY_DIRS),-L$(librarydir))

      

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