Method build

packages/router-core/src/router.ts:1798–2015

(
      dest: BuildNextOptions & {
        unmaskOnReload?: boolean
      } = {},
    )

   */
  buildLocation: BuildLocationFn = (opts) => {
    const build = (
      dest: BuildNextOptions & {
        unmaskOnReload?: boolean
      } = {},
    ): ParsedLocation => {
      // We allow the caller to override the current location
      const currentLocation =
        dest._fromLocation || this.pendingBuiltLocation || this.latestLocation

      // Use lightweight matching - only computes what buildLocation needs
      // (fullPath, search, params) without creating full match objects
      const lightweightResult = this.matchRoutesLightweight(currentLocation)

      // check that from path exists in the current route tree
      // do this check only on navigations during test or development
      if (
        dest.from &&
        process.env.NODE_ENV !== 'production' &&
        dest._isNavigate
      ) {
        const allFromMatches = this.getMatchedRoutes(dest.from).matchedRoutes

        const matchedFrom = findLast(lightweightResult.matchedRoutes, (d) => {
          return comparePaths(d.fullPath, dest.from!)
        })

        const matchedCurrent = findLast(allFromMatches, (d) => {
          return comparePaths(d.fullPath, lightweightResult.fullPath)
        })

        // for from to be invalid it shouldn't just be unmatched to currentLocation
        // but the currentLocation should also be unmatched to from
        if (!matchedFrom && !matchedCurrent) {
          console.warn(`Could not find match for from: ${dest.from}`)
        }
      }

      const defaultedFromPath =
        dest.unsafeRelative === 'path'
          ? currentLocation.pathname
          : (dest.from ?? lightweightResult.fullPath)

      // ensure this includes the basePath if set
      const fromPath = this.resolvePathWithBase(defaultedFromPath, '.')

      // From search should always use the current location
      const fromSearch = lightweightResult.search
      // Same with params. It can't hurt to provide as many as possible
      const fromParams = Object.assign(
        Object.create(null),
        lightweightResult.params,
      )

      // Resolve the next to
      // ensure this includes the basePath if set
      const nextTo = dest.to
        ? this.resolvePathWithBase(fromPath, `${dest.to}`)
        : this.resolvePathWithBase(fromPath, '.')