Inject a source identifer into moc

I have been preaching this for so long to other teams, I really better
clean up my own backyard: Make sure that you can run

    moc --version

and get a somewhat useful indication what version that is. This is
important for when random people use `moc` from random versions of SDK
or – later – build it themselves and then provide bug reports.

When building locally, with `.git` around, this now injects the git
revision:

    $ ./moc --version
    Motoko compiler (revision 9abae15e-dirty)

(the `-dirty` indicates that my work-tee is not clean).

When `.git` is _not_ available, as typially (and rightfully) when
building with nix, it looks if Nix’s `$out` variable is set, and
includes that:

    ~/dfinity/motoko $ $(nix-build -A moc)/bin/moc --version
    Motoko compiler (revision xx6fmamdh5bjph9law6x02d7f4hw8f84-moc-bin)

This is less useful for end-users, but it still allows us to (hopefully)
identify the version, in the worst case by running this command on all
revisions to find the right one:

    $ nix-store --query --outputs $(nix-instantiate -A moc-bin)
    /nix/store/xx6fmamdh5bjph9law6x02d7f4hw8f84-moc-bin

Or by querying hydra (as @basvandijk suggests in
dfinity/sdk#383 (comment))

Once we do versioned releases, we can of course extend this to inject
the version number there, and use `git describe --tag` to have
`v1.0-200-9abae15e` like derscriptions.

I _hope_ this will not cause extra recompilations with `dune`, and will
work out-of-the box for everyone, but we’ll see.

src/Makefile

@@ -13,13 +13,16 @@ DESER_TARGET = _build/default/exes/deser.exe
 
 DUNE_OPTS ?=
 
-ALL_TARGETS = $(MO_IDE_TARGET) $(MO_LD_TARGET) $(MO_DOC_TARGET) $(MOC_TARGET) $(MOC_JS_TARGET) $(DIDC_TARGET) $(DESER_TARGET) ($DIDC_JS_TARGET)
+ALL_TARGETS = $(MO_IDE_TARGET) $(MO_LD_TARGET) $(MO_DOC_TARGET) $(MOC_TARGET) $(MOC_JS_TARGET) $(DIDC_TARGET) $(DESER_TARGET) $(DIDC_JS_TARGET)
 
 .PHONY: all clean moc mo-doc mo-ide mo-ld moc.js didc deser unit-tests didc.js
 
+# let make update check this file every time
+SOURCE_ID = source_id/source_id.ml
+
 # This targets is spelled out so that `make`
 # only invokes `dune` once, much faster
-all: grammar
+all: $(SOURCE_ID) grammar
 	dune build $(DUNE_OPTS) $(ALL_TARGETS)
 	@ln -fs $(MOC_TARGET) moc
 	@ln -fs $(MO_IDE_TARGET) mo-ide
@@ -28,47 +31,58 @@ all: grammar
 	@ln -fs $(MOC_JS_TARGET) moc.js
 	@ln -fs $(DIDC_TARGET) didc
 	@ln -fs $(DESER_TARGET) deser
+	@ln -fs $(DIDC_JS_TARGET) didc.js
 
-moc:
+moc: $(SOURCE_ID)
 	dune build $(DUNE_OPTS) $(MOC_TARGET)
 	@ln -fs $(MOC_TARGET) moc
 
-mo-ide:
+mo-ide: $(SOURCE_ID)
 	dune build $(DUNE_OPTS) $(MO_IDE_TARGET)
 	@ln -fs $(MO_IDE_TARGET) mo-ide
 
-mo-ld:
+mo-ld: $(SOURCE_ID)
 	dune build $(DUNE_OPTS) $(MO_LD_TARGET)
 	@ln -fs $(MO_LD_TARGET) mo-ld
 
-mo-doc:
+mo-doc: $(SOURCE_ID)
 	dune build $(DUNE_OPTS) $(MO_DOC_TARGET)
 	@ln -fs $(MO_DOC_TARGET) mo-doc
 
-moc.js:
+moc.js: $(SOURCE_ID)
 	dune build $(DUNE_OPTS) $(MOC_JS_TARGET)
 	@ln -fs $(MOC_JS_TARGET) moc.js
 
-didc.js:
+didc.js: $(SOURCE_ID)
 	dune build $(DUNE_OPTS) $(DIDC_JS_TARGET)
 	@ln -fs $(DIDC_JS_TARGET) didc.js
 
-didc:
+didc: $(SOURCE_ID)
 	dune build $(DUNE_OPTS) $(DIDC_TARGET)
 	@ln -fs $(DIDC_TARGET) didc
 
-deser:
+deser: $(SOURCE_ID)
 	dune build $(DUNE_OPTS) $(DESER_TARGET)
 	@ln -fs $(DESER_TARGET) deser
 
+.PHONY: $(SOURCE_ID)
+
+# only actually touch the file if changed
+$(SOURCE_ID):
+	source_id/gen.sh
+
 unit-tests:
 	dune runtest $(DUNE_OPTS)
 
 format:
-	ocamlformat --inplace docs/*.mli docs/*.ml languageServer/*.ml languageServer/*.mli
+	ocamlformat --inplace \
+	  docs/*.mli \
+          docs/*.ml \
+          languageServer/*.ml \
+          languageServer/*.mli
 
 clean:
-	rm -f moc mo-ide mo-ld moc.js didc deser
+	rm -f moc mo-ide mo-ld moc.js didc deser $(SOURCE_ID)
 	dune clean
 
 test: $(NAME)
@@ -78,7 +92,6 @@ test: $(NAME)
 test-quick: $(NAME)
 	make -C ../test MOC=$(MOC) quick
 
-
 grammar: ../doc/modules/language-guide/examples/grammar.txt
 
 ../doc/modules/language-guide/examples/grammar.txt: mo_frontend/parser.mly gen-grammar/gen-grammar.sh gen-grammar/grammar.sed

src/exes/deser.ml

@@ -491,8 +491,7 @@ end
 (* CLI *)
 
 let name = "deser"
-let version = "0.1"
-let banner = "Interface Description Language (IDL) " ^ version ^ " message dumper"
+let banner = "Candid toolkit (revision " ^ Source_id.id ^ ")"
 let usage = "Usage: " ^ name ^ " [option] [file ...]"
 
 let mode = ref Nary

src/exes/didc.ml

@@ -2,8 +2,7 @@ open Idllib
 open Printf
 
 let name = "didc"
-let version = "0.1"
-let banner = "Interface Description Language (IDL) " ^ version ^ " interpreter"
+let banner = "Candid compiler (revision " ^ Source_id.id ^ ")"
 let usage = "Usage: " ^ name ^ " [option] [file ...]"
 
 

src/exes/dune

@@ -1,7 +1,7 @@
 (executable
  (name moc)
  (modules moc)
- (libraries profiler pipeline)
+ (libraries profiler pipeline source_id)
 )
 (executable
  (name mo_ide)
@@ -21,10 +21,10 @@
 (executable
  (name didc)
  (modules didc)
- (libraries idllib)
+ (libraries idllib source_id)
 )
 (executable
  (name deser)
  (modules deser)
- (libraries stdio num)
+ (libraries stdio num source_id)
 )

src/exes/moc.ml

@@ -4,8 +4,7 @@ open Mo_config
 open Printf
 
 let name = "moc"
-let version = "0.1"
-let banner = "Motoko " ^ version ^ " interpreter"
+let banner = "Motoko compiler (revision " ^ Source_id.id ^ ")"
 let usage = "Usage: " ^ name ^ " [option] [file ...]"
 
 

src/source_id/.gitignore

@@ -0,0 +1 @@
+source_id.ml

src/source_id/dune

@@ -0,0 +1 @@
+(library (name source_id))

src/source_id/gen.sh

@@ -0,0 +1,18 @@
+#!/bin/bash
+
+cd "$(dirname "$BASH_SOURCE")"
+
+file="source_id.ml"
+
+if [ "$(git rev-parse --is-inside-work-tree 2>/dev/null)" = true ]
+then echo "let id = \"$(git describe --always --dirty)\"" > $file.tmp
+elif [ -n "$out" ]
+then echo "let id = \"$(echo $out|cut -d/ -f4)\"" > $file.tmp
+else echo "let id = \"unidentified version\"" > $file.tmp
+fi
+if [ ! -e $file ] || ! cmp -s $file.tmp $file
+then mv $file.tmp $file
+else rm -f $file.tmp
+fi
+
+