makefiles: Fix escaping issues under GNU make 4.2

Make 4.3 and newer doesn't interpret comments in a shell call,
whereas Make 4.2 and older do. Escaping the comment directly
works on old makes, but on new makes the backslash is passed
as well -- which we want to avoid.

The safe way to pass a literal "#" character to the shell on
both versions is by embedding it in a variable and expanding
that. It's ugly, but it works...

Change-Id: I1a217c42d747fd5aa83f9990c234e06966ac1a00

1 files changed, 8 insertions, 2 deletions

diff --git a/tools/functions.make b/tools/functions.make
index d9acbba2ba..c2237c9547 100644
--- a/tools/functions.make
+++ b/tools/functions.make
@@ -14,12 +14,18 @@
 #
 # The sed line is to prepend the directory to all source files
 
+# This is needed because GNU Make older than 4.3 treats this as the start
+# of a comment even within a $(shell) call and requires a backslash escape.
+# Newer Makes pass the whole "\#" through, making the backslash visible in
+# the shell. To safely pass a literal "#", it has to go in a variable.
+_hash_ = \#
+
 preprocess = $(shell $(CC) $(PPCFLAGS) $(2) -E -P -x c -include config.h $(1) | \
-                grep -v '^#' | grep -v "^ *$$" | \
+                grep -v "^$(_hash_)" | grep -v "^ *$$" | \
                 sed -e 's:^..*:$(dir $(1))&:')
 
 preprocess2file = $(shell $(CC) $(PPCFLAGS) $(3) -E -P -x c -include config.h $(1) | \
-                grep -v '^#' | grep -v "^$$" > $(2))
+                grep -v '^$(_hash_)' | grep -v "^$$" > $(2))
 
 asmdefs2file = $(SILENT)$(CC) $(PPCFLAGS) $(3) -S -x c -o - -include config.h $(1) | \
         perl -ne 'if(/^_?AD_(\w+):$$/){$$var=$$1}else{/^\W\.(?:word|long)\W(.*)$$/ && $$var && print "\#define $$var $$1\n";$$var=0}' > $(2)