Move AST testing rules to Makefile.dev (#8743)

Makefile.dev is only included if a Git clone is detected.

make evaluates macros in target specifications when the Makefile is
read, which meant that the build-all-asts target caused `git ls-files`
to be called on every invocation of make. This tweaks it to be a
recursive call to make which puts the $(AST_FILES) macro in the recipe
where it is only evaluated when the target is requested.

(cherry picked from commit 93ee6b43b05783d56e3d8d984fb2503f5870807d)

3 files changed, 55 insertions, 28 deletions

diff --git a/HACKING.adoc b/HACKING.adoc
index 93c6e4fe67..3941a6f372 100644
--- a/HACKING.adoc
+++ b/HACKING.adoc
@@ -229,6 +229,10 @@ installation, the following targets may be of use:
 
 `make -C testsuite parallel`:: see link:testsuite/HACKING.adoc[]
 
+Additionally, there are some developer specific targets in link:Makefile.dev[].
+These targets are automatically available when working in a Git clone of the
+repository, but are not available from a tarball.
+
 === Bootstrapping
 
 The OCaml compiler is bootstrapped. This means that
diff --git a/Makefile b/Makefile
index 2a9413a97a..83598d6c49 100644
--- a/Makefile
+++ b/Makefile
@@ -1279,34 +1279,9 @@ partialclean::
 
 beforedepend:: bytecomp/opcodes.ml
 
-# Testing the parser -- see parsing/HACKING.adoc
-
-SOURCE_FILES=$(shell git ls-files '*.ml' '*.mli' | grep -v boot/menhir/parser)
-
-AST_FILES=$(addsuffix .ast,$(SOURCE_FILES))
-
-build-all-asts: $(AST_FILES)
-
-CAMLC_DPARSETREE := \
-	$(CAMLRUN) ./ocamlc -nostdlib -nopervasives \
-	  -stop-after parsing -dparsetree
-
-%.ml.ast: %.ml ocamlc
-	$(CAMLC_DPARSETREE) $< 2> $@ || exit 0
-# `|| exit 0` : some source files will fail to parse
-# (for example, they are meant as toplevel scripts
-# rather than source files, or are parse-error tests),
-# we ignore the failure in that case
-
-%.mli.ast: %.mli ocamlc
-	$(CAMLC_DPARSETREE) $< 2> $@ || exit 0
-
-.PHONY: list-all-asts
-list-all-asts:
-	@for f in $(AST_FILES); do echo "'$$f'"; done
-
-partialclean::
-	rm -f $(AST_FILES)
+ifneq "$(wildcard .git)" ""
+include Makefile.dev
+endif
 
 # Default rules
 
diff --git a/Makefile.dev b/Makefile.dev
new file mode 100644
index 0000000000..de69a1bf8f
--- /dev/null
+++ b/Makefile.dev
@@ -0,0 +1,48 @@
+#**************************************************************************
+#*                                                                        *
+#*                                 OCaml                                  *
+#*                                                                        *
+#*            Gabriel Scherer, projet Parsifal, INRIA Saclay              *
+#*                                                                        *
+#*   Copyright 2018 Institut National de Recherche en Informatique et     *
+#*     en Automatique.                                                    *
+#*                                                                        *
+#*   All rights reserved.  This file is distributed under the terms of    *
+#*   the GNU Lesser General Public License version 2.1, with the          *
+#*   special exception on linking described in the file LICENSE.          *
+#*                                                                        *
+#**************************************************************************
+
+# Developer-only rules, included in Makefile when a Git repository is detected.
+
+# Testing the parser -- see parsing/HACKING.adoc
+
+SOURCE_FILES=$(shell git ls-files '*.ml' '*.mli' | grep -v boot/menhir/parser)
+
+AST_FILES=$(addsuffix .ast,$(SOURCE_FILES))
+
+build-all-asts:
+# Recursive invocation ensures that `git ls-files` is not executed on every
+# invocation of make
+	@$(MAKE) --no-print-directory $(AST_FILES)
+
+CAMLC_DPARSETREE := \
+	$(CAMLRUN) ./ocamlc -nostdlib -nopervasives \
+	  -stop-after parsing -dparsetree
+
+%.ml.ast: %.ml ocamlc
+	$(CAMLC_DPARSETREE) $< 2> $@ || exit 0
+# `|| exit 0` : some source files will fail to parse
+# (for example, they are meant as toplevel scripts
+# rather than source files, or are parse-error tests),
+# we ignore the failure in that case
+
+%.mli.ast: %.mli ocamlc
+	$(CAMLC_DPARSETREE) $< 2> $@ || exit 0
+
+.PHONY: list-all-asts
+list-all-asts:
+	@for f in $(AST_FILES); do echo "'$$f'"; done
+
+partialclean::
+	rm -f $(AST_FILES)