build: Add stage2scan.c and byte comparison check for bootstrap.

With stage1scan.c being deterministic, it's possible to add a bootstrap check that ensures the generated flex program can build the scanner of itself flawlessly. The check is performed on native build only. Signed-off-by: Kang-Che Sung <[email protected]>
westes · Feb 15, 2020 · 5e34608 · 5e34608
1 parent 4c8b757
commit 5e34608
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Showing 2 changed files with 11 additions and 1 deletion.
diff --git a/src/.gitignore b/src/.gitignore
@@ -9,5 +9,6 @@ parse.c
 parse.h
 scan.c
 skel.c
-stage1scan.[cl]
+stage1scan.c
 stage1flex
+stage2scan.c
diff --git a/src/Makefile.am b/src/Makefile.am
@@ -8,6 +8,9 @@ m4 = @M4@
 bin_PROGRAMS = flex
 if ENABLE_BOOTSTRAP
 noinst_PROGRAMS = stage1flex
+if !CROSS
+noinst_DATA = stage2scan.c
+endif
 endif
 
 if ENABLE_LIBFL
@@ -110,6 +113,12 @@ stage1scan.c: scan.l stage1flex$(EXEEXT)
 	( cd $(srcdir) && $(abs_builddir)/stage1flex$(EXEEXT) \
 	  $(AM_LFLAGS) -o scan.c -t $(LFLAGS) scan.l ) >$@
 
+stage2scan.c: scan.l flex$(EXEEXT) stage1scan.c
+	@echo "Checking if flex produces bit-for-bit identical scanner of itself..."
+	( cd $(srcdir) && $(abs_builddir)/flex$(EXEEXT) \
+	  $(AM_LFLAGS) -o scan.c -t $(LFLAGS) scan.l ) >$@ && \
+	cmp stage1scan.c $@
+
 dist-hook: scan.l flex$(EXEEXT)
 	chmod u+w $(distdir) && \
 	( cd $(srcdir) && $(abs_builddir)/flex$(EXEEXT) \