Redirect $(WASM)/lib/R/bin JS binaries to use native R (#367)

* Redirect $(WASM)/lib/R/bin binaries to native R

The binaries built by Emscripten in $(WASM)/lib/R/bin are JavaScript
output, unable to be run directly by the host machine. Such binaries can
be run using Node, but require some further setup (e.g. relocation of
the required `R.wasm` file).

Since these scrips do not work, Makevars targets relying on executing
R code using `$(R_HOME)/bin/R` fail. The `symbols.rds` target in
`lib/share/make/shlib.mk` is an example.

With this commit, these specific scripts are redirected to use the
version of R compiled for the host machine, working around the issue.

* Update NEWS.md

NEWS.md

@@ -44,6 +44,8 @@
 
 * Fixed spelling errors in some JavaScript errors thrown by webR.
 
+* The `symbols.rds` make target should now work when building R packages using `rwasm` (r-wasm/rwasm#13).
+
 * Rasters with negative width or height are now drawn mirrored or flipped when using the canvas graphics device (#350).
 
 * Include `cex` parameters when calculating font size in canvas graphics device (#348).

R/Makefile

@@ -205,7 +205,7 @@ MAKE_WASM_BUILD += R_ENABLE_JIT="false"
 MAKE_WASM_BUILD += WEBR_HOST_METHODS="$(R_HOST)/lib/R/library/methods"
 MAKE_WASM_BUILD += FORTRAN_WASM_LDADD="$(FORTRAN_WASM_LDADD)"
 
-MAKE_WASM_INSTALL := $(MAKE_WASM)
+MAKE_WASM_INSTALL := R_HOST="$(R_HOST)" $(MAKE_WASM)
 
 # Build lazy virtual filesystem, backed by XHR when loaded in browsers
 WASM_LAZY_VFS := $(WASM_LAZY_VFS)

patches/R-4.3.2/emscripten-makefiles.diff

@@ -20,7 +20,7 @@ Index: R-4.3.0/src/main/Makefile.in
 ===================================================================
 --- R-4.3.0.orig/src/main/Makefile.in
 +++ R-4.3.0/src/main/Makefile.in
-@@ -149,6 +149,51 @@ $(R_binary): $(R_bin_OBJECTS) $(R_bin_DEPENDENCIES)
+@@ -149,6 +149,56 @@ $(R_binary): $(R_bin_OBJECTS) $(R_bin_DEPENDENCIES)
  $(R_binary): $(R_bin_OBJECTS) $(R_bin_DEPENDENCIES)
  	$(MAIN_LINK) -o $@ $(R_bin_OBJECTS) $(R_bin_LDADD)
 
@@ -68,6 +68,11 @@ Index: R-4.3.0/src/main/Makefile.in
 +# Patch Emscripten library to redirect a warning message to console.warn()
 +	@sed -i.bak 's/out("LazyFiles/console.warn("LazyFiles/' $(prefix)/dist/$(R_binary).js
 +	@rm $(prefix)/dist/$(R_binary).js.bak
++# Redirect $(WASM)/lib R binaries to $(HOST)/lib R binaries
++	@mv $(prefix)/lib/R/bin/R $(prefix)/lib/R/bin/R.orig
++	@mv $(prefix)/lib/R/bin/Rscript $(prefix)/lib/R/bin/Rscript.orig
++	@ln -s $(R_HOST)/lib/R/bin/R $(prefix)/lib/R/bin/R
++	@ln -s $(R_HOST)/lib/R/bin/Rscript $(prefix)/lib/R/bin/Rscript
 +
  libR.a: $(OBJECTS) $(STATIC_LIBS)
  	-@mkdir libs