use filterdiff tool if available to strip timestamps from example

The diff tool will emit a timestamp along with the diff. This
timestamps prevents build output from being consistent between
builds.

If the filterdiff tool is detected, use it to strip the timestamp
and allow for reproducible build output.

git-svn-id: svn+ssh://svn.code.sf.net/p/check/code/trunk@1224 64e312b2-a51f-0410-8e61-82d0ca0eb02a

AUTHORS

@@ -55,6 +55,7 @@ Contributors:
     Sebastian Dröge       (Kill running tests if SIGTERM or SIGINT are caught in test runner)
     Matt Clarkson         (Fix CMake checks using time.h for MinGW and MSVC)
     Mario Sanchez Prada   (configure.ac cleanup)
+    Tobias Frost          (strip timestamps from examples to enable reproducible builds)
 
 Anybody who has contributed code to Check or Check's build system is
 considered an author.  Send patches to this file to 

NEWS

@@ -4,6 +4,10 @@ In Development:
 * Add LGPL header to files where it was missing; update FSF address in LGPL headers
   Bug #110
 
+* Strip timestamps from examples using filterdiff if available. This
+  allow build output to be reproducible.
+  Bug #112
+
 Sun Aug 2, 2015: Released Check 0.10.0
   based on r1217 (2015-08-02 19:21:14 +0000)
 

configure.ac

@@ -181,6 +181,15 @@ if test "$TEX" = "false"; then
     # anyway.
     AC_MSG_WARN(tex not installed: cannot rebuild HTML documentation.)
 fi
+AC_CHECK_PROGS(FILTERDIFF, filterdiff, false)
+if test "$FILTERDIFF" = "false"; then
+    # Make it [somewhat] clear to maintainers that filterdiff is missing.
+    # This is not an error, but will prevent builds from being
+    # reproducible.
+    AC_MSG_WARN(filterdiff not installed; build will not be reproducible.)
+fi
+
+AM_CONDITIONAL(USE_FILTERDIFF, [test x"$FILTERDIFF" = x"filterdiff"])
 
 # Checks for pthread implementation.
 ACX_PTHREAD

doc/Makefile.am

@@ -26,54 +26,63 @@ eg_root = $(top_srcdir)/doc/example
 eg_src = $(eg_root)/src
 eg_tests = $(eg_root)/tests
 
+# If the filterdiff tool is available, use it to filter timestamps
+# from diff files. Otherwise, the timestamps change between builds
+# and the built output will not be reproducible
+if USE_FILTERDIFF
+    filter_timestapms = | filterdiff --remove-timestamps
+else
+    filter_timestapms =
+endif
+
 ## now a rule for each diff.  the redundancy here can probably be
 ## parameterized, but I don't know how.  if you know, please tell us!
 
 # diff returns 1 if there is a difference, but we don't want make to
 # think that means there is an error
 money.1-2.h.diff: $(eg_src)/money.1.h $(eg_src)/money.2.h
 	cd $(eg_root); \
-	diff -U 100 src/money.1.h src/money.2.h > @abs_builddir@/$@ || test $$? -eq 1; \
+	diff -U 100 src/money.1.h src/money.2.h ${filter_timestapms} > @abs_builddir@/$@ || test $$? -eq 1; \
 	cd -;
 
 money.1-3.c.diff: $(eg_src)/money.1.c $(eg_src)/money.3.c
 	cd $(eg_root); \
-	diff -U 100 src/money.1.c src/money.3.c > @abs_builddir@/$@ || test $$? -eq 1; \
+	diff -U 100 src/money.1.c src/money.3.c ${filter_timestapms} > @abs_builddir@/$@ || test $$? -eq 1; \
 	cd -;
 
 money.3-4.c.diff: $(eg_src)/money.3.c $(eg_src)/money.4.c
 	cd $(eg_root); \
-	diff -U 100 src/money.3.c src/money.4.c > @abs_builddir@/$@ || test $$? -eq 1; \
+	diff -U 100 src/money.3.c src/money.4.c ${filter_timestapms} > @abs_builddir@/$@ || test $$? -eq 1; \
 	cd -;
 
 money.4-5.c.diff: $(eg_src)/money.4.c $(eg_src)/money.5.c
 	cd $(eg_root); \
-	diff -U 100 src/money.4.c src/money.5.c > @abs_builddir@/$@ || test $$? -eq 1; \
+	diff -U 100 src/money.4.c src/money.5.c ${filter_timestapms} > @abs_builddir@/$@ || test $$? -eq 1; \
 	cd -;
 
 money.5-6.c.diff: $(eg_src)/money.5.c $(eg_src)/money.6.c
 	cd $(eg_root); \
-	diff -U 100 src/money.5.c src/money.6.c > @abs_builddir@/$@ || test $$? -eq 1; \
+	diff -U 100 src/money.5.c src/money.6.c ${filter_timestapms} > @abs_builddir@/$@ || test $$? -eq 1; \
 	cd -;
 
 check_money.1-2.c.diff: $(eg_tests)/check_money.1.c $(eg_tests)/check_money.2.c
 	cd $(eg_root); \
-	diff -U 100 tests/check_money.1.c tests/check_money.2.c > @abs_builddir@/$@ || test $$? -eq 1; \
+	diff -U 100 tests/check_money.1.c tests/check_money.2.c ${filter_timestapms} > @abs_builddir@/$@ || test $$? -eq 1; \
 	cd -;
 
 check_money.2-3.c.diff: $(eg_tests)/check_money.2.c $(eg_tests)/check_money.3.c
 	cd $(eg_root); \
-	diff -U 100 tests/check_money.2.c tests/check_money.3.c > @abs_builddir@/$@ || test $$? -eq 1; \
+	diff -U 100 tests/check_money.2.c tests/check_money.3.c ${filter_timestapms} > @abs_builddir@/$@ || test $$? -eq 1; \
 	cd -;
 
 check_money.3-6.c.diff: $(eg_tests)/check_money.3.c $(eg_tests)/check_money.6.c
 	cd $(eg_root); \
-	diff -U 100 tests/check_money.3.c tests/check_money.6.c > @abs_builddir@/$@ || test $$? -eq 1; \
+	diff -U 100 tests/check_money.3.c tests/check_money.6.c ${filter_timestapms} > @abs_builddir@/$@ || test $$? -eq 1; \
 	cd -;
 
 check_money.6-7.c.diff: $(eg_tests)/check_money.6.c $(eg_tests)/check_money.7.c
 	cd $(eg_root); \
-	diff -U 100 tests/check_money.6.c tests/check_money.7.c > @abs_builddir@/$@ || test $$? -eq 1; \
+	diff -U 100 tests/check_money.6.c tests/check_money.7.c ${filter_timestapms} > @abs_builddir@/$@ || test $$? -eq 1; \
 	cd -;
 
 # explicitly list every file in the example.