Fix srcset parse error (#7295)

* Fix srcset parse

* Don't swallow error

* fix srcset parse

* Add changelog

* Update case

* Fix quote style

* Make input ugly

changelog_unreleased/html/pr-7295.md

@@ -0,0 +1,27 @@
+#### Fix srcset parse error ([#7295](https://github.com/prettier/prettier/pull/7295) by [@fisker](https://github.com/fisker))
+
+<!-- prettier-ignore -->
+```html
+<!-- Input -->
+<img
+
+srcset="
+             /media/examples/surfer-240-200.jpg
+">
+
+<!-- Prettier stable -->
+Error: Mixed descriptor in srcset is not supported
+    at printImgSrcset (https://prettier.io/lib/standalone.js:20867:13)
+    at printEmbeddedAttributeValue (https://prettier.io/lib/standalone.js:21538:26)
+    at Object.embed$2 [as embed] (https://prettier.io/lib/standalone.js:21009:43)
+    at Object.printSubtree (https://prettier.io/lib/standalone.js:15170:30)
+    at callPluginPrintFunction (https://prettier.io/lib/standalone.js:15288:31)
+    at https://prettier.io/lib/standalone.js:15253:18
+    at Object.printComments (https://prettier.io/lib/standalone.js:14974:19)
+    at printGenerically (https://prettier.io/lib/standalone.js:15252:24)
+    at https://prettier.io/lib/standalone.js:21285:175
+    at FastPath.map (https://prettier.io/lib/standalone.js:15155:23)
+
+<!-- Prettier master -->
+<img srcset="/media/examples/surfer-240-200.jpg" />
+```

src/language-html/syntax-attribute.js

@@ -18,7 +18,7 @@ function printImgSrcset(value) {
   const hasH = srcset.some(src => src.h);
   const hasX = srcset.some(src => src.d);
 
-  if (hasW + hasH + hasX !== 1) {
+  if (hasW + hasH + hasX > 1) {
     throw new Error("Mixed descriptor in srcset is not supported");
   }
 

tests/html_attributes/__snapshots__/jsfmt.spec.js.snap

@@ -319,6 +319,11 @@ sizes="(max-width: 66rem) 100vw, 66rem" alt=""/>
 <img src="/assets/visual.png" 
 srcset="/assets/visual@0.5.png  0.5x, /assets/visual.png      1111x,	/assets/visual@2x.png   2x,	/assets/visual@3x.png   3.3333x" 
 sizes="(max-width: 66rem) 100vw, 66rem" alt=""/>
+<img
+
+srcset="
+             /media/examples/surfer-240-200.jpg
+">
 
 =====================================output=====================================
 <img
@@ -349,6 +354,7 @@ sizes="(max-width: 66rem) 100vw, 66rem" alt=""/>
   sizes="(max-width: 66rem) 100vw, 66rem"
   alt=""
 />
+<img srcset="/media/examples/surfer-240-200.jpg" />
 
 ================================================================================
 `;

tests/html_attributes/srcset.html

@@ -7,3 +7,8 @@ sizes="(max-width: 66rem) 100vw, 66rem" alt=""/>
 <img src="/assets/visual.png" 
 srcset="/assets/visual@0.5.png  0.5x, /assets/visual.png      1111x,	/assets/visual@2x.png   2x,	/assets/visual@3x.png   3.3333x" 
 sizes="(max-width: 66rem) 100vw, 66rem" alt=""/>
+<img
+
+srcset="
+             /media/examples/surfer-240-200.jpg
+">