From 56ce1fc12651e9cf60b882a18d72a410967d6540 Mon Sep 17 00:00:00 2001
From: John MacFarlane <jgm@berkeley.edu>
Date: Wed, 24 Mar 2021 11:57:49 -0700
Subject: Fix DocBook reader mathml regression...

...caused by the switch in XML libraries.
Also fixed a similar issue in JATS.
Closes #7173.
---
 src/Text/Pandoc/Readers/DocBook.hs |   3 +-
 src/Text/Pandoc/Readers/JATS.hs    |   8 ++-
 test/command/7173.md               | 137 +++++++++++++++++++++++++++++++++++++
 test/docbook-reader.docbook        |   4 +-
 4 files changed, 147 insertions(+), 5 deletions(-)
 create mode 100644 test/command/7173.md

diff --git a/src/Text/Pandoc/Readers/DocBook.hs b/src/Text/Pandoc/Readers/DocBook.hs
index 6f5bb0ad4..4f525cfb1 100644
--- a/src/Text/Pandoc/Readers/DocBook.hs
+++ b/src/Text/Pandoc/Readers/DocBook.hs
@@ -1239,7 +1239,8 @@ equation e constructor =
   where
     mathMLEquations :: [Text]
     mathMLEquations = map writeTeX $ rights $ readMath
-      (\x -> qName (elName x) == "math" && qPrefix (elName x) == Just "mml")
+      (\x -> qName (elName x) == "math" &&
+             qURI (elName x) == Just "http://www.w3.org/1998/Math/MathML")
       (readMathML . showElement)
 
     latexEquations :: [Text]
diff --git a/src/Text/Pandoc/Readers/JATS.hs b/src/Text/Pandoc/Readers/JATS.hs
index 602f3b4f2..c068f3774 100644
--- a/src/Text/Pandoc/Readers/JATS.hs
+++ b/src/Text/Pandoc/Readers/JATS.hs
@@ -491,7 +491,8 @@ parseInline (Elem e) =
 
         "disp-formula" -> formula displayMath
         "inline-formula" -> formula math
-        "math" | qPrefix (elName e) == Just "mml" -> return . math $ mathML e
+        "math" | qURI (elName e) == Just "http://www.w3.org/1998/Math/MathML"
+                   -> return . math $ mathML e
         "tex-math" -> return . math $ textContent e
 
         "email" -> return $ link ("mailto:" <> textContent e) ""
@@ -514,8 +515,9 @@ parseInline (Elem e) =
                             filterChildren isMathML whereToLook
             return . mconcat . take 1 . map constructor $ texMaths ++ mathMLs
 
-         isMathML x = qName   (elName x) == "math" &&
-                      qPrefix (elName x) == Just "mml"
+         isMathML x = qName (elName x) == "math" &&
+                      qURI  (elName x) ==
+                                      Just "http://www.w3.org/1998/Math/MathML"
          removePrefix elname = elname { qPrefix = Nothing }
          codeWithLang = do
            let classes' = case attrValue "language" e of
diff --git a/test/command/7173.md b/test/command/7173.md
new file mode 100644
index 000000000..2599dc19b
--- /dev/null
+++ b/test/command/7173.md
@@ -0,0 +1,137 @@
+```
+% pandoc -f docbook -t latex
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE article PUBLIC "-//W3C//DTD MathML 2.0//EN" "http://www.w3.org/Math/DTD/mathml2/mathml2.dtd">
+<?xml-model href="http://www.oxygenxml.com/docbook/xml/5.0/rng/dbmathml.rng" schematypens="http://relaxng.org/ns/structure/1.0"?>
+<?xml-model href="http://docbook.org/xml/5.0/rng/docbook.rng" type="application/xml" schematypens="http://purl.oclc.org/dsdl/schematron"?>
+<article xmlns="http://docbook.org/ns/docbook"
+    xmlns:xlink="http://www.w3.org/1999/xlink"
+    version="5.1">
+    <title>Untitled Document</title>
+    <para>Word</para>
+    <informalequation>
+        <alt role='tex'>1+2</alt>
+        <m:math xmlns:m="http://www.w3.org/1998/Math/MathML">
+            <m:mrow>
+                <m:mrow><m:mn>1</m:mn><m:mo>+</m:mo><m:mn>2</m:mn>
+                </m:mrow>
+            </m:mrow>
+        </m:math>
+    </informalequation>
+</article>
+^D
+Word
+
+\[1 + 2\]
+```
+
+```
+% pandoc -f docbook -t latex
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE article PUBLIC "-//W3C//DTD MathML 2.0//EN" "http://www.w3.org/Math/DTD/mathml2/mathml2.dtd">
+<?xml-model href="http://www.oxygenxml.com/docbook/xml/5.0/rng/dbmathml.rng" schematypens="http://relaxng.org/ns/structure/1.0"?>
+<?xml-model href="http://docbook.org/xml/5.0/rng/docbook.rng" type="application/xml" schematypens="http://purl.oclc.org/dsdl/schematron"?>
+<article xmlns="http://docbook.org/ns/docbook"
+    xmlns:xlink="http://www.w3.org/1999/xlink"
+    version="5.1">
+    <title>Untitled Document</title>
+    <para>Word</para>
+    <informalequation>
+        <alt role='tex'>1+2</alt>
+        <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
+            <mml:mrow>
+                <mml:mrow><mml:mn>1</mml:mn><mml:mo>+</mml:mo><mml:mn>2</mml:mn>
+                </mml:mrow>
+            </mml:mrow>
+        </mml:math>
+    </informalequation>
+</article>
+^D
+Word
+
+\[1 + 2\]
+```
+
+```
+% pandoc -f docbook -t latex
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE article PUBLIC "-//W3C//DTD MathML 2.0//EN" "http://www.w3.org/Math/DTD/mathml2/mathml2.dtd">
+<?xml-model href="http://www.oxygenxml.com/docbook/xml/5.0/rng/dbmathml.rng" schematypens="http://relaxng.org/ns/structure/1.0"?>
+<?xml-model href="http://docbook.org/xml/5.0/rng/docbook.rng" type="application/xml" schematypens="http://purl.oclc.org/dsdl/schematron"?>
+<article xmlns="http://docbook.org/ns/docbook"
+    xmlns:xlink="http://www.w3.org/1999/xlink"
+    version="5.1">
+    <title>Untitled Document</title>
+    <para>Word</para>
+    <informalequation>
+        <alt role='tex'>1+2</alt>
+        <math xmlns="http://www.w3.org/1998/Math/MathML">
+            <mrow>
+                <mrow><mn>1</mn><mo>+</mo><mn>2</mn>
+                </mrow>
+            </mrow>
+        </math>
+    </informalequation>
+</article>
+^D
+Word
+
+\[1 + 2\]
+```
+
+```
+% pandoc -f docbook -t latex
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE article PUBLIC "-//W3C//DTD MathML 2.0//EN" "http://www.w3.org/Math/DTD/mathml2/mathml2.dtd">
+<?xml-model href="http://www.oxygenxml.com/docbook/xml/5.0/rng/dbmathml.rng" schematypens="http://relaxng.org/ns/structure/1.0"?>
+<?xml-model href="http://docbook.org/xml/5.0/rng/docbook.rng" type="application/xml" schematypens="http://purl.oclc.org/dsdl/schematron"?>
+<article xmlns="http://docbook.org/ns/docbook"
+    xmlns:xlink="http://www.w3.org/1999/xlink"
+    xmlns:m="http://www.w3.org/1998/Math/MathML"
+    version="5.1">
+    <title>Untitled Document</title>
+    <para>Word</para>
+    <informalequation>
+        <alt role='tex'>1+2</alt>
+        <m:math>
+            <m:mrow>
+                <m:mrow><m:mn>1</m:mn><m:mo>+</m:mo><m:mn>2</m:mn>
+                </m:mrow>
+            </m:mrow>
+        </m:math>
+    </informalequation>
+</article>
+^D
+Word
+
+\[1 + 2\]
+```
+
+```
+% pandoc -f docbook -t latex
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE article PUBLIC "-//W3C//DTD MathML 2.0//EN" "http://www.w3.org/Math/DTD/mathml2/mathml2.dtd">
+<?xml-model href="http://www.oxygenxml.com/docbook/xml/5.0/rng/dbmathml.rng" schematypens="http://relaxng.org/ns/structure/1.0"?>
+<?xml-model href="http://docbook.org/xml/5.0/rng/docbook.rng" type="application/xml" schematypens="http://purl.oclc.org/dsdl/schematron"?>
+<article xmlns="http://docbook.org/ns/docbook"
+    xmlns:xlink="http://www.w3.org/1999/xlink"
+    xmlns:mml="http://www.w3.org/1998/Math/MathML"
+    version="5.1">
+    <title>Untitled Document</title>
+    <para>Word</para>
+    <informalequation>
+        <alt role='tex'>1+2</alt>
+        <mml:math>
+            <mml:mrow>
+                <mml:mrow><mml:mn>1</mml:mn><mml:mo>+</mml:mo><mml:mn>2</mml:mn>
+                </mml:mrow>
+            </mml:mrow>
+        </mml:math>
+    </informalequation>
+</article>
+^D
+Word
+
+\[1 + 2\]
+```
+
diff --git a/test/docbook-reader.docbook b/test/docbook-reader.docbook
index 5717d78d0..51e62942b 100644
--- a/test/docbook-reader.docbook
+++ b/test/docbook-reader.docbook
@@ -6,7 +6,9 @@
 <!ENTITY let "LET" >
 <!ENTITY case "CASE" >
 ]>
-<article>
+<article xmlns="http://docbook.org/ns/docbook"
+         xmlns:xlink="http://www.w3.org/1999/xlink"
+         xmlns:mml="http://www.w3.org/1998/Math/MathML">
   <articleinfo>
     <title>Pandoc Test Suite</title>
     <authorgroup>
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