Repairs and improvements for building with external dependencies (#807)

* configure: fix zlib and lz4 submodule checks

Conditionals to skip the submodule checks were using the wrong
variable names, so the checks were always skipped. The correct
behavior is to perform the check unless given `ZLIB=<zlib>` or
`LZ4=<lz4>`, as applicable.

* configure: support `ZUO=<zuo>`

Supplying `ZUO=<zuo>` skips the submodule check in `configure`
and configures the generated makefile not to build or remove Zuo.

* configure: support `STEXLIB=<stex>`

For compatibility with older scripts, when not explicitly configured,
continue to honor the `STEXLIB` environment variable at build time.

4 files changed, 47 insertions, 17 deletions

diff --git a/BUILDING b/BUILDING
index 7b3dc9c8..9e9a268b 100644
--- a/BUILDING
+++ b/BUILDING
@@ -149,7 +149,8 @@ information on the supported options.
 The generated makefile mostly just ensures that a `zuo` executable is
 built in a `bin` directory, and then it defers the actual build work
 to `zuo`, which uses the "main.zuo" file. If you have `zuo` installed,
-you can use `zuo` directly instead of `make`. In general, instead of
+you can use `zuo` directly instead of `make`: in that case, you may
+wish to use `./configure ZUO=<zuo>`. In general, instead of
 the command `make X` to build target `X` as described below, you can
 use `zuo . X` (or `bin/zuo . X` after `bin/zuo` is built).
 
@@ -333,7 +334,7 @@ The makefile supports several targets:
  * `make clean`
 
    Removes all built elements from the workarea, and then removes
-   `bin/zuo`.
+   `bin/zuo` (unless configured with `ZUO=<zuo>`).
 
 
 WINDOWS VIA COMMAND PROMPT
diff --git a/build.zuo b/build.zuo
index c21d2caa..c5896396 100644
--- a/build.zuo
+++ b/build.zuo
@@ -224,10 +224,15 @@
            token))
 
   (define stexlib
-    (let ((found (assoc "STEXLIB" (hash-ref (runtime-env) 'env))))
-      (if found
-          (cdr found)
-          (at-source "stex"))))
+    (let ([configured (hash-ref config 'STEXLIB "")]
+          [env (assoc "STEXLIB" (hash-ref (runtime-env) 'env))])
+      (cond
+        [(not (equal? "" configured))
+         configured]
+        [env
+         (cdr env)]
+        [else
+         (at-source "stex")])))
   (define stex-sources
     (source-tree stexlib))
 
diff --git a/configure b/configure
index 2b4b594e..782dd09b 100755
--- a/configure
+++ b/configure
@@ -93,6 +93,7 @@ default_warning_flags="-Wpointer-arith -Wall -Wextra -Wno-implicit-fallthrough"
 CFLAGS_ADD=
 zlibLib=
 LZ4Lib=
+STEXLIB=
 Kernel=KernelLib
 buildKernelOnly=no
 enableFrompb=yes
@@ -103,6 +104,7 @@ moreBootFiles=
 preloadBootFiles=
 alwaysUseBootFile=
 skipSubmoduleUpdate=
+zuoExternal=
 
 CONFIG_UNAME=`uname`
 
@@ -446,6 +448,12 @@ while [ $# != 0 ] ; do
     LZ4=*)
       LZ4Lib=`echo $1 | sed -e 's/^LZ4=//'`
       ;;
+    STEXLIB=*)
+      STEXLIB=`echo $1 | sed -e 's/^STEXLIB=//'`
+      ;;
+    ZUO=*)
+      zuoExternal=`echo $1 | sed -e 's/^ZUO=//'`
+      ;;
     *)
       echo "option '$1' unrecognized or missing an argument; try $0 --help"
       exit 1
@@ -672,6 +680,8 @@ if [ "$help" = "yes" ]; then
   echo "  STRIP=<strip>                     executable stripper"
   echo "  ZLIB=<lib>                        link to <lib> instead of own zlib"
   echo "  LZ4=<lib>                         link to <lib> instead of own LZ4"
+  echo "  STEXLIB=<stex>                    build docs with <stex> instead of own stex"
+  echo "  ZUO=<zuo>                         build with <zuo> instead of own Zuo"
   echo ""
   echo "Available machine types: $machs"
   echo ""
@@ -889,28 +899,39 @@ submod_instructions () {
     exit 1
 }
 
-if [ ! -f "$srcdir"/zuo/configure ] ; then
-    submod_instructions 'Source in "zuo" is missing'
+if [ "${zuoExternal}" = "" ] ; then
+    if [ ! -f "$srcdir"/zuo/configure ] ; then
+        submod_instructions 'Source in "zuo" is missing'
+    fi
+    ZUO="bin/zuo"
+    RM_ZUO="rm -f bin/zuo"
+    ZUO_TARGET="bin/zuo"
+else
+    ZUO="${zuoExternal}"
+    RM_ZUO="@echo 'Not cleaning external ${zuoExternal}'"
+    ZUO_TARGET="DoNotBuildZuo"
 fi
 
 if [ ! -f "$srcdir"/nanopass/nanopass.ss ] ; then
     submod_instructions 'Source in "nanopass" is missing'
 fi
 
-if [ "${zlibDep}" != "" ] ; then
+if [ "${zlibLib}" = "" ] ; then
     if [ ! -f "$srcdir"/zlib/configure ] ; then
         submod_instructions 'Source in "zlib" is missing'
     fi
 fi
 
-if [ "${LZ4Dep}" != "" ] ; then
+if [ "${LZ4Lib}" = "" ] ; then
     if [ ! -f "$srcdir"/lz4/lib/Makefile ] ; then
         submod_instructions 'Source in "lz4" is missing'
     fi
 fi
 
-if [ ! -f "$srcdir"/stex/Mf-stex ] ; then
-    submod_instructions 'Source in "stex" is missing'
+if [ "${STEXLIB}" = "" ] ; then
+    if [ ! -f "$srcdir"/stex/Mf-stex ] ; then
+        submod_instructions 'Source in "stex" is missing'
+    fi
 fi
 
 # more compile and link flags for c/Mf-unix and mats/Mf-unix
@@ -1083,7 +1104,7 @@ cp "$srcdir"/makefiles/buildmain.zuo main.zuo
 # Some idea, but in the workarea, so it refers to "workarea.zuo" here:
 cp "$srcdir"/makefiles/workmain.zuo $w/main.zuo
 
-# The content of "$w/Makefile" records configuration decisions,
+# The content of "$w/Mf-config" records configuration decisions,
 # and the Zuo build script takes it from there
 cat > $w/Mf-config << END
 srcdir=$srcdir
@@ -1119,6 +1140,7 @@ cursesLib=$cursesLib
 ncursesLib=$ncursesLib
 zlibLib=$zlibLib
 LZ4Lib=$LZ4Lib
+STEXLIB=$STEXLIB
 warningFlags=$warningFlags
 Kernel=$Kernel
 installscriptname=$installscriptname
@@ -1130,6 +1152,10 @@ preloadBootFiles=$preloadBootFiles
 alwaysUseBootFile=$alwaysUseBootFile
 relativeBootFiles=$relativeBootFiles
 
+ZUO=$ZUO
+RM_ZUO=$RM_ZUO
+ZUO_TARGET=$ZUO_TARGET
+
 InstallBin=$installbin
 InstallLib=$installlib
 InstallMan=$installman/man1
diff --git a/makefiles/Makefile.in b/makefiles/Makefile.in
index 3b95f065..0e3d307d 100644
--- a/makefiles/Makefile.in
+++ b/makefiles/Makefile.in
@@ -3,8 +3,6 @@ workarea=$(w)
 
 include $(workarea)/Mf-config
 
-ZUO=bin/zuo
-
 .PHONY: build
 build: $(ZUO)
 	+ $(ZUO) $(workarea) MAKE="$(MAKE)"
@@ -144,9 +142,9 @@ pkg: $(ZUO)
 .PHONY: clean
 clean: $(ZUO)
 	+ $(ZUO) $(workarea) clean MAKE="$(MAKE)"
-	rm -f bin/zuo
+	$(RM_ZUO)
 
 # Using `+` here means that $(ZUO) gets built even if `-n`/`--dry-run` is provided to `make`
-$(ZUO): $(srcdir)/zuo/zuo.c
+$(ZUO_TARGET): $(srcdir)/zuo/zuo.c
 	+ mkdir -p bin
 	+ $(CC_FOR_BUILD) -DZUO_LIB_PATH='"'"../zuo/lib"'"' -o $(ZUO) $(srcdir)/zuo/zuo.c