wip: new cssVars SSR integration + fix cssVars SSR injection for suspense

packages/compiler-sfc/src/compileTemplate.ts

@@ -22,6 +22,7 @@ import { isObject } from '@vue/shared'
 import * as CompilerDOM from '@vue/compiler-dom'
 import * as CompilerSSR from '@vue/compiler-ssr'
 import consolidate from 'consolidate'
+import { warnOnce } from './warn'
 
 export interface TemplateCompiler {
   compile(template: string, options: CompilerOptions): CodegenResult
@@ -170,6 +171,14 @@ function doCompileTemplate({
     nodeTransforms = [transformAssetUrl, transformSrcset]
   }
 
+  if (ssr && !compilerOptions.ssrCssVars) {
+    warnOnce(
+      `compileTemplate is called with \`ssr: true\` but no ` +
+        `corresponding \`ssrCssVars\` option. The value can be generated by ` +
+        `calling \`generateCssVars(sfcDescriptor, scopeId, isProduction)\`.`
+    )
+  }
+
   let { code, ast, preamble, map } = compiler.compile(source, {
     mode: 'module',
     prefixIdentifiers: true,