Improve LaTeX version checking

Instead of having to add and individually test the versions to check
for, we store the current version and test on that with a specific
function isAvailableAtLeastFrom(package, year, month, day)

Currently only used for the LaTeX version, but could also be extended
for package versions.

lib/chkconfig.ltx

@@ -75,8 +75,8 @@
 \newcommand{\AddVariable}[2]{
   \immediate\write\vars{chk_#1='#2'}}
 
-\newcommand{\AddPackage}[1]{
-  \immediate\write\packages{#1}}
+\newcommand{\AddPackage}[2][]{
+  \immediate\write\packages{#2 #1}}
 
 % Tests whether an item is present
 % Syntax: \TestItem[<file>]{<name>}{<type>}{<ext>}{<iftrue>}{<iffalse>}
@@ -148,20 +148,6 @@
   \fi}
 
 
-% Test for the LaTeX version
-\newcommand{\TestLaTeXVersion}[1]{
-  \message{^^J\prefix checking for LaTeX version at least as of #1...}
-  \@ifl@t@r\fmtversion{#1}{\existstrue}{\existsfalse}
-  \ifexists
-    \message{yes^^J}
-    \AddVariable{#1}{yes}
-    \AddPackage{LaTeX-#1}
-  \else
-    \message{no^^J}
-    \AddVariable{#1}{no}
-  \fi}
-
-
 % Adapted from ltxcheck.tex
 \newcommand{\TestFont}[2][\default]{
   \def\default{#2}
@@ -180,6 +166,7 @@
   \fi}
 
 \newcommand{\TestPackage}[2][\default]{
+  \def\default{#2}
   \TestItem[#1]{#2}{package}{sty}{\AddPackage{#2}}{}}
 
 \newcommand{\TestDocClass}[2]{
@@ -234,20 +221,8 @@
 \message{^^J\prefix checking for LaTeX version... \fmtversion}
 \AddVariable{fmtversion}{\fmtversion}
 
-%%% Crucial versions
-% This one introduces \textsubscript
-\TestLaTeXVersion{2005/12/01}
-% This one introduces \UseRawInputEncoding
-\TestLaTeXVersion{2018/04/01}
-% This one introduces path encoding changes
-\TestLaTeXVersion{2019/10/01}
-% This introduces all math and text spaces
-% previously only available via amsmath
-\TestLaTeXVersion{2020/10/01}
-% This robustifies LaTeX commands
-\TestLaTeXVersion{2021/06/01}
-% Introduction of \\DocumentMetadata
-\TestLaTeXVersion{2022/06/01}
+%%% Store the current LaTeX version
+\AddPackage[\fmtversion]{LaTeX}
 
 %%% And now, the list of available languages
 % The trick is to know that \the\everyjob contains something like

src/Buffer.cpp

@@ -1966,7 +1966,7 @@ Buffer::ExportStatus Buffer::writeLaTeXSource(otexstream & os,
 					docdir = subst(docdir, "~", "\\string~");
 				bool const nonascii = !isAscii(from_utf8(docdir));
 				// LaTeX 2019/10/01 handles non-ascii path without detokenize
-				bool const utfpathlatex = features.isAvailable("LaTeX-2019/10/01");
+				bool const utfpathlatex = features.isAvailableAtLeastFrom("LaTeX", 2019, 10);
 				bool const detokenize = !utfpathlatex && nonascii;
 				bool const quote = contains(docdir, ' ');
 				if (utfpathlatex && nonascii)

src/BufferParams.cpp

@@ -1703,7 +1703,7 @@ bool BufferParams::writeLaTeX(otexstream & os, LaTeXFeatures & features,
 			      FileName const & filepath) const
 {
 	// DocumentMetadata must come before anything else
-	if (features.isAvailable("LaTeX-2022/06/01")
+	if (features.isAvailableAtLeastFrom("LaTeX", 2022, 6)
 	    && !containsOnly(document_metadata, " \n\t")) {
 		// Check if the user preamble contains uncodable glyphs
 		odocstringstream doc_metadata;
@@ -3430,7 +3430,7 @@ void BufferParams::writeEncodingPreamble(otexstream & os,
 		case Encoding::japanese:
 			if (encoding().iconvName() != "UTF-8"
 			    && !features.runparams().isFullUnicode()
-			    && features.isAvailable("LaTeX-2018/04/01"))
+			    && features.isAvailableAtLeastFrom("LaTeX", 2018, 4))
 				// don't default to [utf8]{inputenc} with LaTeX >= 2018/04
 				os << "\\UseRawInputEncoding\n";
 			break;
@@ -3457,7 +3457,7 @@ void BufferParams::writeEncodingPreamble(otexstream & os,
 		}
 	}
 	if ((inputenc == "auto-legacy-plain" || features.isRequired("japanese"))
-	    && features.isAvailable("LaTeX-2018/04/01"))
+	    && features.isAvailableAtLeastFrom("LaTeX", 2018, 4))
 		// don't default to [utf8]{inputenc} with LaTeX >= 2018/04
 		os << "\\UseRawInputEncoding\n";
 }

src/LaTeXFeatures.cpp

@@ -827,6 +827,12 @@ bool LaTeXFeatures::isAvailable(string const & name)
 }
 
 
+bool LaTeXFeatures::isAvailableAtLeastFrom(string const & name, int const y, int const m, int const d)
+{
+	return LaTeXPackages::isAvailableAtLeastFrom(name, y, m, d);
+}
+
+
 namespace {
 
 void addSnippet(std::list<TexString> & list, TexString ts, bool allow_dupes)
@@ -1514,7 +1520,7 @@ string const LaTeXFeatures::getPackages() const
 
 	// fixltx2e provides subscript
 	if (mustProvide("subscript") && !isRequired("fixltx2e")
-	    && !isAvailable("LaTeX-2005/12/01"))
+	    && !isAvailableAtLeastFrom("LaTeX", 2005, 12))
 		packages << "\\usepackage{subscript}\n";
 
 	// footmisc must be loaded after setspace

src/LaTeXFeatures.h

@@ -108,6 +108,10 @@ public:
 	void provide(std::string const & name);
 	/// Is the (required) package available?
 	static bool isAvailable(std::string const & name);
+	/// Is the (required) package available at least as of version
+	/// y/m/d?
+	static bool isAvailableAtLeastFrom(std::string const & name,
+					   int const y, int const m, int const d = 1);
 	/// Has the package been required?
 	bool isRequired(std::string const & name) const;
 	/** Is this feature already provided

src/LaTeXPackages.cpp

@@ -18,10 +18,13 @@
 
 #include "Lexer.h"
 
+#include "support/convert.h"
 #include "support/FileName.h"
 #include "support/filetools.h"
 #include "support/lstrings.h"
 
+#include <regex>
+
 
 using namespace std;
 using namespace lyx::support;
@@ -55,8 +58,13 @@ void LaTeXPackages::getAvailable()
 		case Lexer::LEX_FEOF:
 			finished = true;
 			break;
-		default:
-			packages_.insert(lex.getString());
+		default: {
+			string const p = lex.getString();
+			// Parse optional version info
+			lex.eatLine();
+			string const v = lex.getString();
+			packages_.insert(make_pair(p, v));
+		}
 		}
 	}
 }
@@ -69,7 +77,59 @@ bool LaTeXPackages::isAvailable(string const & name)
 	string n = name;
 	if (suffixIs(n, ".sty"))
 		n.erase(name.length() - 4);
-	return packages_.find(n) != packages_.end();
+	for (auto const & package : packages_) {
+		if (package.first == n)
+			return true;
+	}
+	return false;
+}
+
+
+bool LaTeXPackages::isAvailableAtLeastFrom(string const & name,
+					   int const y, int const m, int const d)
+{
+	if (packages_.empty())
+		getAvailable();
+
+	bool result = false;
+	// Check for yyyy-mm-dd
+	static regex const reg("([\\d]{4})-([\\d]{2})-([\\d]{2})");
+	for (auto const & package : packages_) {
+		if (package.first == name && !package.second.empty()) {
+			smatch sub;
+			if (regex_match(package.second, sub, reg)) {
+				// Test whether date is same or newer.
+				//
+				// Test for year first
+				int const avail_y = convert<int>(sub.str(1));
+				if (avail_y < y)
+					// our year is older: bad!
+					break;
+				if (avail_y > y) {
+					// our year is newer: good!
+					result = true;
+					break;
+				}
+				// Same year: now test month
+				int const avail_m = convert<int>(sub.str(2));
+				if (avail_m < m)
+					// our month is older: bad!
+					break;
+				if (avail_m > m) {
+					// our month is newer: good!
+					result = true;
+					break;
+				}
+				// Same year and month: test day
+				if (convert<int>(sub.str(3)) >= d) {
+					// day same or newer: good!
+					result = true;
+					break;
+				}
+			}
+		}
+	}
+	return result;
 }
 
 } // namespace lyx

src/LaTeXPackages.h

@@ -28,9 +28,13 @@ public:
 	static void getAvailable();
 	/// Is the (required) package available?
 	static bool isAvailable(std::string const & name);
+	/// Is the (required) package available at least as of
+	/// version y/m/d?
+	static bool isAvailableAtLeastFrom(std::string const & name,
+					   int const y, int const m, int const d = 1);
 private:
 	/// The available (required) packages
-	typedef std::set<std::string> Packages;
+	typedef std::set<std::pair<std::string,std::string>> Packages;
 	///
 	static Packages packages_;
 };

src/insets/InsetSpace.cpp

@@ -895,7 +895,7 @@ docstring InsetSpace::xhtml(XMLStream & xs, OutputParams const &) const
 
 void InsetSpace::validate(LaTeXFeatures & features) const
 {
-	if (features.isAvailable("LaTeX-2020/10/01"))
+	if (features.isAvailableAtLeastFrom("LaTeX", 2020, 10))
 		// As of this version, the LaTeX kernel
 		// includes all spaces.
 		return;

src/mathed/InsetMathGrid.cpp

@@ -1252,7 +1252,7 @@ void InsetMathGrid::write(TeXMathStream & os,
 	// \\ is a robust command and its protection
 	// is no longer necessary
 	bool const fragile = os.fragile()
-			&& !LaTeXFeatures::isAvailable("LaTeX-2021/06/01");
+			&& !LaTeXFeatures::isAvailableAtLeastFrom("LaTeX", 2021, 06);
 	for (row_type row = beg_row; row < end_row; ++row) {
 		os << verboseHLine(rowinfo_[row].lines);
 		// don't write & and empty cells at end of line,