texlive.withPackages: generate formats in separate derivations (#291396)

Generate TeX formats into separate derivations so that they can be
shared across different environments, considerably reducing build times.

pkgs/tools/typesetting/tex/texlive/build-tex-env.nix

···
 , __combine ? false
 # adjust behavior further if called from the texlive.combine wrapper
 , __fromCombineWrapper ? false
+# build only the formats of a package (for internal use!)
+, __formatsOf ? null
 }@args:
 
 let
···
     hyphenPatterns = lib.filter (p: p ? hyphenPatterns && (p.tlOutputName or p.outputName == "tex")) nonbin;
     sortedHyphenPatterns = builtins.sort (a: b: a.pname < b.pname) hyphenPatterns;
     formatPkgs = lib.filter (p: p ? formats && (p.outputSpecified or false -> p.tlOutputName or p.outputName == "tex") && builtins.any (f: f.enabled or true) p.formats) all;
-    sortedFormatPkgs = builtins.sort (a: b: a.pname < b.pname) formatPkgs;
+    sortedFormatPkgs = if __formatsOf != null then [ __formatsOf ] else builtins.sort (a: b: a.pname < b.pname) formatPkgs;
+    formats = map (p: self { requiredTeXPackages = ps: [ ps.scheme-infraonly p ] ++ hyphenPatterns; __formatsOf = p; }) sortedFormatPkgs;
   };
 
   # list generated by inspecting `grep -IR '\([^a-zA-Z]\|^\)gs\( \|$\|"\)' "$TEXMFDIST"/scripts`
···
   needsGhostscript = lib.any (p: lib.elem p.pname [ "context" "dvipdfmx" "latex-papersize" "lyluatex" ]) pkgList.bin;
 
   name = if __combine then "texlive-${__extraName}-${bin.texliveYear}${__extraVersion}" # texlive.combine: old name name
-    else "texlive-${bin.texliveYear}-env";
+    else "texlive-${bin.texliveYear}-" + (if __formatsOf != null then "${__formatsOf.pname}-fmt" else "env");
 
   texmfdist = buildEnv' {
     name = "${name}-texmfdist";
···
   inherit name;
 
   # use attrNames, attrValues to ensure the two lists are sorted in the same way
-  outputs = [ "out" ] ++ lib.optionals (! __combine) (builtins.attrNames nonEnvOutputs);
-  otherOutputs = lib.optionals (! __combine) (builtins.attrValues nonEnvOutputs);
+  outputs = [ "out" ] ++ lib.optionals (! __combine && __formatsOf == null) (builtins.attrNames nonEnvOutputs);
+  otherOutputs = lib.optionals (! __combine && __formatsOf == null) (builtins.attrValues nonEnvOutputs);
 
   # remove fake derivations (without 'outPath') to avoid undesired build dependencies
-  paths = builtins.catAttrs "outPath" pkgList.bin
+  paths = builtins.catAttrs "outPath" pkgList.bin ++ lib.optionals (! __combine && __formatsOf == null) pkgList.formats
     ++ lib.optional __combine doc;
   pathsToLink = [
     "/"
···
 
   buildInputs = [ coreutils gawk gnugrep gnused ] ++ lib.optional needsGhostscript ghostscript;
 
-  inherit meta passthru;
+  inherit meta passthru __combine;
+  __formatsOf = __formatsOf.pname or null;
 
   inherit texmfdist texmfroot;
 
···
   '';
 };
   # outputsToInstall must be set *after* overrideAttrs (used in buildEnv') or it fails the checkMeta tests
-in if __combine then out else lib.addMetaAttrs { inherit (pkgList) outputsToInstall; } out)
+in if __combine || __formatsOf != null then out else lib.addMetaAttrs { inherit (pkgList) outputsToInstall; } out)

pkgs/tools/typesetting/tex/texlive/build-tex-env.sh

···
     # in principle, we could use writeText and share them across different
     # environments, but the eval & build overhead is not worth the savings
     tlutils_create_fmtutil
-    tlutils_create_updmap
+    # can be skipped if generating formats only
+    if [[ -z $__formatsOf ]] ; then
+        tlutils_create_updmap
+    fi
     tlutils_create_language_dat
     tlutils_create_language_def
     tlutils_create_language_lua
···
     tlutils_info "running mktexlsr $TEXMFSYSVAR $TEXMFSYSCONFIG"
     mktexlsr "$TEXMFSYSVAR" "$TEXMFSYSCONFIG"
 
-    # update font maps
-    tlutils_info "generating font maps"
-    updmap-sys --quiet --force --nohash 2>&1
-    # configure the paper size
-    # tlmgr --no-execute-actions paper letter
-    # install-tl: "rerun mktexlsr for updmap-sys and tlmgr paper updates"
-    tlutils_info "re-running mktexlsr $TEXMFSYSVAR $TEXMFSYSCONFIG"
-    mktexlsr "$TEXMFSYSVAR" "$TEXMFSYSCONFIG"
+    # can be skipped if generating formats only
+    if [[ -z $__formatsOf ]] ; then
+        # update font maps
+        tlutils_info "generating font maps"
+        updmap-sys --quiet --force --nohash 2>&1
+        # configure the paper size
+        # tlmgr --no-execute-actions paper letter
+        # install-tl: "rerun mktexlsr for updmap-sys and tlmgr paper updates"
+        tlutils_info "re-running mktexlsr $TEXMFSYSVAR $TEXMFSYSCONFIG"
+        mktexlsr "$TEXMFSYSVAR" "$TEXMFSYSCONFIG"
 
-    tlutils_update_context_cache
+        tlutils_update_context_cache
+    fi
 
     # generate formats
     # install-tl would run fmtutil-sys $common_fmtutil_args --no-strict --all
     # instead, we want fmtutil to exit with error on failure
-    if [[ -n $fmtutilCnf ]] ; then
+    if [[ -n $fmtutilCnf && -n $__combine$__formatsOf ]] ; then
         tlutils_info "pre-generating all format files, be patient..."
         # many formats still ignore SOURCE_DATE_EPOCH even when FORCE_SOURCE_DATE=1
         # libfaketime fixes non-determinism related to timestamps ignoring FORCE_SOURCE_DATE
···
         substitute "$texmfdist"/scripts/texlive/fmtutil.pl fmtutil \
             --replace-fail "my \$cmdline = \"\$eng -ini " "my \$cmdline = \"faketime -f '\@$(date +'%F %T' --date=@"$SOURCE_DATE_EPOCH") x0.001' \$eng -ini "
         FORCE_SOURCE_DATE=1 perl fmtutil --quiet --strict --sys --all 2>&1 | grep '^fmtutil' # too verbose
+
+        # if generating formats only, delete everything else and exit
+        if [[ -n $__formatsOf ]] ; then
+            # see fmtutil.pl::compute_format_destination for file extensions
+            find "$out" \( -type f -or -type l \) \
+                -not -path "$TEXMFSYSVAR/*.mem" \
+                -not -path "$TEXMFSYSVAR/*.base" \
+                -not -path "$TEXMFSYSVAR/*.fmt" \
+                -delete
+            find "$out" -type d -empty -delete
+            exit
+        fi
+    elif [[ -z $__combine ]] ; then
+        # double check that all formats are present
+        if fmtutil --quiet --strict --sys --missing --dry-run 2>&1 | grep running ; then
+            tlutils_info 'formats not found, aborting'
+            exit 1
+        fi
     fi
 
     installtl_do_path_adjustments
···
 ### TeXLive::TLUtils
 
 tlutils_info () {
-    printf '%s\n' "texlive: $*"
+    printf "texlive${__formatsOf:+($__formatsOf-fmt)}: %s\n" "$*"
 }
 
 tlutils_create_fmtutil () {