From 1c84d0ca821f847eb34a848dc7150007f2c8c46b Mon Sep 17 00:00:00 2001
From: Guillaume Munch <gm@lyx.org>
Date: Thu, 3 Nov 2016 23:23:11 +0100
Subject: [PATCH] Don't parse multicolumn if the grid does not support it

Fixes #10466 and visual/compilation bugs with InsetMathSplit, InsetMathDiagram,
InsetMathHull, InsetMathSubstack and InsetMathXYMatrix.
---
 src/mathed/InsetMathAMSArray.h | 2 ++
 src/mathed/InsetMathArray.h    | 2 ++
 src/mathed/InsetMathCases.h    | 2 ++
 src/mathed/InsetMathGrid.h     | 2 ++
 src/mathed/InsetMathHull.cpp   | 1 -
 src/mathed/InsetMathMatrix.h   | 2 ++
 src/mathed/InsetMathSplit.cpp  | 5 -----
 src/mathed/InsetMathTabular.h  | 2 ++
 src/mathed/MathParser.cpp      | 2 +-
 9 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/src/mathed/InsetMathAMSArray.h b/src/mathed/InsetMathAMSArray.h
index 584397302d..c337c781a0 100644
--- a/src/mathed/InsetMathAMSArray.h
+++ b/src/mathed/InsetMathAMSArray.h
@@ -58,6 +58,8 @@ public:
 	int leftMargin() const { return 6; } //override
 	///
 	int rightMargin() const { return 8; } //override
+	///
+	bool handlesMulticolumn() const { return true; } //override
 
 private:
 	virtual Inset * clone() const;
diff --git a/src/mathed/InsetMathArray.h b/src/mathed/InsetMathArray.h
index a3875e58b7..b1cc3110ab 100644
--- a/src/mathed/InsetMathArray.h
+++ b/src/mathed/InsetMathArray.h
@@ -53,6 +53,8 @@ public:
 	int leftMargin() const { return 4; } //override
 	///
 	int rightMargin() const { return 2; } //override
+	///
+	bool handlesMulticolumn() const { return true; } //override
 
 private:
 	virtual Inset * clone() const;
diff --git a/src/mathed/InsetMathCases.h b/src/mathed/InsetMathCases.h
index 3b44b823ca..84e13979e8 100644
--- a/src/mathed/InsetMathCases.h
+++ b/src/mathed/InsetMathCases.h
@@ -56,6 +56,8 @@ public:
 	int leftMargin() const { return 8; } //override
 	///
 	int rightMargin() const { return 0; } //override
+	/// see e.g. https://tex.stackexchange.com/a/133283/87201
+	bool handlesMulticolumn() const { return true; } //override
 
 private:
 	virtual Inset * clone() const;
diff --git a/src/mathed/InsetMathGrid.h b/src/mathed/InsetMathGrid.h
index 61e7e235c8..4300dc3188 100644
--- a/src/mathed/InsetMathGrid.h
+++ b/src/mathed/InsetMathGrid.h
@@ -211,6 +211,8 @@ public:
 	virtual int vlinesep() const;
 	///
 	virtual int border() const;
+	///
+	virtual bool handlesMulticolumn() const { return false; }
 
 	///
 	void write(WriteStream & os) const;
diff --git a/src/mathed/InsetMathHull.cpp b/src/mathed/InsetMathHull.cpp
index 2bb8822acc..e2ceb5c903 100644
--- a/src/mathed/InsetMathHull.cpp
+++ b/src/mathed/InsetMathHull.cpp
@@ -15,7 +15,6 @@
 #include "InsetMathChar.h"
 #include "InsetMathColor.h"
 #include "InsetMathFrac.h"
-#include "InsetMathGrid.h"
 #include "InsetMathNest.h"
 #include "InsetMathScript.h"
 #include "MathExtern.h"
diff --git a/src/mathed/InsetMathMatrix.h b/src/mathed/InsetMathMatrix.h
index 26a8544026..d64ba3006c 100644
--- a/src/mathed/InsetMathMatrix.h
+++ b/src/mathed/InsetMathMatrix.h
@@ -47,6 +47,8 @@ public:
 	void octave(OctaveStream &) const;
 	///
 	InsetCode lyxCode() const { return MATH_MATRIX_CODE; }
+	///
+	bool handlesMulticolumn() const { return true; } //override
 
 private:
 	virtual Inset * clone() const;
diff --git a/src/mathed/InsetMathSplit.cpp b/src/mathed/InsetMathSplit.cpp
index e385e0a09a..fb2ecbe083 100644
--- a/src/mathed/InsetMathSplit.cpp
+++ b/src/mathed/InsetMathSplit.cpp
@@ -48,11 +48,6 @@ Inset * InsetMathSplit::clone() const
 }
 
 
-// FIXME: InsetMathGrid should be changed to let the real column alignment be
-// given by a virtual method like displayColAlign, because the values produced
-// by defaultColAlign can be invalidated by lfuns such as add-column. I suspect
-// that for the moment the values produced by defaultColAlign are not used,
-// notably because alignment is not implemented in the LyXHTML output.
 char InsetMathSplit::defaultColAlign(col_type col)
 {
 	if (name_ == "gathered")
diff --git a/src/mathed/InsetMathTabular.h b/src/mathed/InsetMathTabular.h
index ed88bd633f..481d28ef0e 100644
--- a/src/mathed/InsetMathTabular.h
+++ b/src/mathed/InsetMathTabular.h
@@ -49,6 +49,8 @@ public:
 	int leftMargin() const { return 4; } //override
 	///
 	int rightMargin() const { return 2; } //override
+	///
+	bool handlesMulticolumn() const { return true; } //override
 
 private:
 	Inset * clone() const;
diff --git a/src/mathed/MathParser.cpp b/src/mathed/MathParser.cpp
index 4504a13a26..ffb828361c 100644
--- a/src/mathed/MathParser.cpp
+++ b/src/mathed/MathParser.cpp
@@ -1363,7 +1363,7 @@ bool Parser::parse1(InsetMathGrid & grid, unsigned flags,
 			}
 		}
 
-		else if (t.cs() == "multicolumn") {
+		else if (t.cs() == "multicolumn" && grid.handlesMulticolumn()) {
 			// if the columns are specified numerically,
 			// extract column count and insert dummy cells,
 			// otherwise parse it as an user macro