Fix \hphantom width (#1809)

* Fix \hphantom width

* Spin up phony screenshot test

* Make better choice of smash screenshot test

* Real screenshotter test

* Add strict mode

* Fix lint error

* useStrictBehavior

* Revert to previous strict setting

* useStrictBehavior "phantomSpacing"

* Fix tests via nonstrictSettings

* Fix documentation

* Remove bin|rel

docs/options.md

@@ -21,6 +21,7 @@ You can provide an object of options as the last argument to [`katex.render` and
   - `"commentAtEnd"`: Use of `%` comment without a terminating newline.
     LaTeX would thereby comment out the end of math mode (e.g. `$`),
     causing an error.
+
   A second category of `errorCode`s never throw errors, but their strictness
   affects the behavior of KaTeX:
   - `"newLineInDisplayMode"`: Use of `\\` or `\newline` in display mode

src/functions/phantom.js

@@ -71,7 +71,8 @@ defineFunction({
             children: [{type: "elem", elem: node}],
         }, options);
 
-        return node;
+        // For spacing, TeX treats \smash as a math group (same spacing as ord).
+        return buildCommon.makeSpan(["mord"], [node], options);
     },
     mathmlBuilder: (group, options) => {
         const inner = mml.buildExpression(ordargument(group.body), options);

src/functions/smash.js

@@ -55,7 +55,7 @@ defineFunction({
     },
     htmlBuilder: (group, options) => {
         const node = buildCommon.makeSpan(
-            ["mord"], [html.buildGroup(group.body, options)]);
+            [], [html.buildGroup(group.body, options)]);
 
         if (!group.smashHeight && !group.smashDepth) {
             return node;
@@ -85,10 +85,13 @@ defineFunction({
         // makeVList applies "display: table-cell", which prevents the browser
         // from acting on that line height. So we'll call makeVList now.
 
-        return buildCommon.makeVList({
+        const smashedNode = buildCommon.makeVList({
             positionType: "firstBaseline",
             children: [{type: "elem", elem: node}],
         }, options);
+
+        // For spacing, TeX treats \hphantom as a math group (same spacing as ord).
+        return buildCommon.makeSpan(["mord"], [smashedNode], options);
     },
     mathmlBuilder: (group, options) => {
         const node = new mathMLTree.MathNode(

test/katex-spec.js

@@ -2008,6 +2008,17 @@ describe("A bin builder", function() {
     });
 });
 
+describe("A \\phantom builder and \\smash builder", function() {
+    it("should both build a mord", function() {
+        expect(getBuilt`\hphantom{a}`[0].classes).toContain("mord");
+        expect(getBuilt`a\hphantom{=}b`[2].classes).toContain("mord");
+        expect(getBuilt`a\hphantom{+}b`[2].classes).toContain("mord");
+        expect(getBuilt`\smash{a}`[0].classes).toContain("mord");
+        expect(getBuilt`\smash{=}`[0].classes).toContain("mord");
+        expect(getBuilt`a\smash{+}b`[2].classes).toContain("mord");
+    });
+});
+
 describe("A markup generator", function() {
     it("marks trees up", function() {
         // Just a few quick sanity checks here...
@@ -2462,15 +2473,15 @@ describe("A smash parser", function() {
 
 describe("A smash builder", function() {
     it("should not fail", function() {
-        expect`\smash{x}`.toBuild();
-        expect`\smash{x^2}`.toBuild();
-        expect`\smash{x}^2`.toBuild();
-        expect`\smash x`.toBuild();
+        expect`\smash{x}`.toBuild(nonstrictSettings);
+        expect`\smash{x^2}`.toBuild(nonstrictSettings);
+        expect`\smash{x}^2`.toBuild(nonstrictSettings);
+        expect`\smash x`.toBuild(nonstrictSettings);
 
-        expect`\smash[b]{x}`.toBuild();
-        expect`\smash[b]{x^2}`.toBuild();
-        expect`\smash[b]{x}^2`.toBuild();
-        expect`\smash[b] x`.toBuild();
+        expect`\smash[b]{x}`.toBuild(nonstrictSettings);
+        expect`\smash[b]{x^2}`.toBuild(nonstrictSettings);
+        expect`\smash[b]{x}^2`.toBuild(nonstrictSettings);
+        expect`\smash[b] x`.toBuild(nonstrictSettings);
     });
 });
 

test/screenshotter/ss_data.yaml

@@ -280,7 +280,7 @@ OverUnderset: |
     \end{array}
 Phantom: \begin{array}{l}
             \dfrac{1+\phantom{x^{\blue{2}}} = x}{1+x^{\blue{2}} = x} \left(\vphantom{\int_t} zzz \right) \left( X \hphantom{\frac{\frac X X}{X}} \right)\\
-            \text{a \phantom{123} b \hphantom{45678} c \vphantom{101112} d}
+            \text{a \phantom{123}} b \hphantom{\frac{1}{2}}=c \vphantom{101112} d
          \end{array}
 Pmb: \mu\pmb{\mu}\pmb{=}\mu\pmb{+}\mu
 PrimeSpacing: f'+f_2'+f^{f'}
@@ -308,7 +308,7 @@ SizingBaseline:
     post: M
 Sizing: |
     {\Huge x}{\LARGE y}{\normalsize z}{\scriptsize w}\sqrt[\small 3]{x+1}
-Smash: \left( X^{\smash 2} \right) \sqrt{\smash[b]{y}}
+Smash: \left( X^{\smash 2} \right) \sqrt{\smash[b]{y=}}
 Spacing: |
     \begin{matrix}
         ^3+[-1][1-1]1=1(=1)\lvert a\rvert~b \\