feat: ssr support for <style vars>

packages/compiler-core/src/codegen.ts

@@ -204,10 +204,11 @@ export function generate(
     genFunctionPreamble(ast, context)
   }
 
-  // enter render function
+  // binding optimizations
   const optimizeSources = options.bindingMetadata
     ? `, $props, $setup, $data, $options`
     : ``
+  // enter render function
   if (!ssr) {
     if (genScopeId) {
       push(`const render = ${PURE_ANNOTATION}_withId(`)

packages/compiler-core/src/options.ts

@@ -126,6 +126,11 @@ export interface TransformOptions {
    * `ssrRender` option instead of `render`.
    */
   ssr?: boolean
+  /**
+   * SFC <style vars> injection string
+   * needed to render inline CSS variables on component root
+   */
+  ssrCssVars?: string
   /**
    * Optional binding metadata analyzed from script - used to optimize
    * binding access when `prefixIdentifiers` is enabled.

packages/compiler-core/src/transform.ts

@@ -120,6 +120,7 @@ export function createTransformContext(
     expressionPlugins = [],
     scopeId = null,
     ssr = false,
+    ssrCssVars = ``,
     bindingMetadata = {},
     onError = defaultOnError
   }: TransformOptions
@@ -136,6 +137,7 @@ export function createTransformContext(
     expressionPlugins,
     scopeId,
     ssr,
+    ssrCssVars,
     bindingMetadata,
     onError,
 
@@ -148,7 +150,7 @@ export function createTransformContext(
     imports: new Set(),
     temps: 0,
     cached: 0,
-    identifiers: {},
+    identifiers: Object.create(null),
     scopes: {
       vFor: 0,
       vSlot: 0,