Experimental Physics and
Industrial Control System

Hi All,

attached are the patches to base/configure in 3.14.8.2 that enable 
correct handling of external dependencies for C header files and dbd 
files. (As I mentioned earlier, for libraries this is already done). 
They are extremely simple changes, in fact they are a simplification 
because we merely remove the filtering of *.depends files to those for 
which the effective path name of the dependency is relative, i.e. 
starts with a dot.

Two variables (HDEPENDS_INCLUDES, DBDDEPENDS_FLAGS) in two files 
(CONFIG_COMMON, RULES.Db) are involved. The patch also contains a 
bugfix for configure/tools/mkmf.pl, but this fix does not extend or 
otherwise change the intended semantics (as I understood it). Apart 
from simplifying the code, it lifts some (artificial) restrictions on 
allowed characters in the names of included files.

[Note: this does not address the question of what to do if 
configure/RELEASE has been changed. I think that a change in 
configure/RELEASE should cause rebuilding of everything -- currently 
this has to be done manually (by doing 'make distclean all').]

I am quite sure that these changes don't break anything. They are 
conservative, in the sense that the dependency graph gets strictly 
larger, thus in the worst case your application gets rebuilt when it 
would not necessarily need to be.

Can anyone think of a scenario where adding the external dependencies 
for C header and dbd files would break anything? I don't believe so, 
however if this were the case, it would be easy to introduce a 
configuration variable to switch off the feature. I have not provided 
such a switch because I think (until proven wrong) that it would be an 
unnecessary complication and the new behavior is strictly better.

Andrew expressed concern about possible loss of efficiency. I have not 
done any measurements because it doesn't seem to be a problem: I have 
not noticed any difference in build times. (But note that in almost all 
cases you get a huge speed-up compared to the 
better-make-sure-all-gets-rebuilt 'make distclean all' approach).

Cheers
Ben
-- 
To the functional programmer's eye a loop is just a degenerate
form of linear recursion written in an adhoc special syntax.

Index: CONFIG_COMMON
===================================================================
RCS file: /opt/repositories/controls/epics/base/3.14/configure/CONFIG_COMMON,v
retrieving revision 1.1.1.5
diff -r1.1.1.5 CONFIG_COMMON
308,309c308
< # Use only dependancies from current top tree
< HDEPENDS_INCLUDES = $(filter .%,$(subst -I,,$(INCLUDES)))
---
> HDEPENDS_INCLUDES = $(subst -I,,$(INCLUDES))
Index: RULES.Db
===================================================================
RCS file: /opt/repositories/controls/epics/base/3.14/configure/RULES.Db,v
retrieving revision 1.1.1.6
diff -r1.1.1.6 RULES.Db
81c81
< DBDDEPENDS_FLAGS = $(filter .%,$(subst -I,,$(filter-out -S%,$(DBDFLAGS))))
---
> DBDDEPENDS_FLAGS = $(subst -I,,$(filter-out -S%,$(DBDFLAGS)))
Index: tools/mkmf.pl
===================================================================
RCS file: /opt/repositories/controls/epics/base/3.14/configure/tools/mkmf.pl,v
retrieving revision 1.1.1.1
diff -r1.1.1.1 mkmf.pl
34d33
< my %delim_match = ( q/'/ => q/'/, q/"/ => q/"/);
142,145c141,143
<    return 0 if !($line =~ m/^[	  ]*\#?[	 ]*include/);
<    return 0 if !($line =~ /^[\#?\s]*include\s*(['""'<])([\w\.\/]*)$delim_match{\1}/ix);
<    return 0 if !$2;
<    $incname = $2;
---
>    return 0 if not $line =~ /^#?\s*include\s*('.*?'|<.*?>|".*?")/;
>    $incname = substr $1, 1, length($1)-2;
>    print "DEBUG: $incname\n" if $debug;
158d155
< 

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