Fix vertical space before equation in latex (closes: #4574)

sphinx/writers/latex.py

@@ -1959,6 +1959,10 @@ class LaTeXTranslator(nodes.NodeVisitor):
             if id.startswith('index-'):
                 return
 
+            # equations also need no extra blank line nor hypertarget
+            if id.startswith('equation-'):
+                return
+
             # insert blank line, if the target follows a paragraph node
             index = node.parent.index(node)
             if index > 0 and isinstance(node.parent[index - 1], nodes.paragraph):

tests/roots/test-latex-equations/conf.py

@@ -0,0 +1,5 @@
+# -*- coding: utf-8 -*-
+
+master_doc = 'equations'
+extensions = ['sphinx.ext.imgmath']
+

tests/roots/test-latex-equations/equations.rst

@@ -0,0 +1,21 @@
+test-latex-equation
+===================
+
+Equation without a label.
+
+.. math::
+
+   E = mc^2
+
+Equation with label.
+
+.. math:: E = hv
+   :label: test
+
+Second equation without label.
+
+.. math::
+
+   c^2 = a^2 + b^2
+
+Equation with label :eq:`test` is important.

tests/roots/test-latex-equations/expects/latex-equations.tex

@@ -0,0 +1,13 @@
+Equation without a label.
+\begin{equation*}
+\begin{split}E = mc^2\end{split}
+\end{equation*}
+Equation with label.
+\begin{equation}\label{equation:equations:test}
+\begin{split}E = hv\end{split}
+\end{equation}
+Second equation without label.
+\begin{equation*}
+\begin{split}c^2 = a^2 + b^2\end{split}
+\end{equation*}
+Equation with label \eqref{equation:equations:test} is important.

tests/test_build_latex.py

@@ -1134,6 +1134,16 @@ def test_latex_index(app, status, warning):
     assert '\n\\index{Einstein}\\index{relativity}\\ignorespaces \nand' in result
 
 
+@pytest.mark.sphinx('latex', testroot='latex-equations')
+def test_latex_equations(app, status, warning):
+    app.builder.build_all()
+
+    result = (app.outdir / 'Python.tex').text(encoding='utf8')
+    expected = (app.srcdir / 'expects' / 'latex-equations.tex').text().strip()
+
+    assert expected in result
+
+
 @pytest.mark.sphinx('latex', testroot='image-in-parsed-literal')
 def test_latex_image_in_parsed_literal(app, status, warning):
     app.builder.build_all()