Broken xref internal links are rendered as anchors to current page

[spalladino]

An incorrect internal xref link, such as xref:upgrades::writing-contracts.adoc instead of xref:upgrades::writing-upgradeable.adoc (see https://github.com/OpenZeppelin/openzeppelin-sdk/commit/1b21b2946b889ae85651d8e7318ff2e8118a725c) is rendered as a link to https://docs.openzeppelin.com/cli/2.6/dependencies#upgrades::writing-contracts.adoc#use-upgradeable-packages.

This makes it impossible to detect broken links with a wget spider. We should either scan for these links in the generated html, or configure the asciidoc processor so that it fails if the xref target is not found.

[frangio]

Some discussion here: https://gitlab.com/antora/antora/issues/403

[frangio]

We can collect all of the links and find those that end in .adoc as a way to find the broken ones.

[frangio]

I compiled a list of pages and broken xrefs they contain using the procedure I described in the previous comment.

sdk/first
learn::deploy-and-interact.adoc

starter-kits/gsnkit
network-js:index.adoc

starter-kits/index
sdk::index.adoc
learn::on-daps.adoc

learn/building-a-dapp
network.js::api.adoc

learn/upgrading-smart-contracts
mainnet.adoc
mainnet.adoc

gsn-provider/0.1/gsn-faq
contracts:api:gsn.adoc
contracts:api:gsn.adoc
contracts:api:gsn.adoc
contracts:api:gsn.adoc
contracts:api:gsn.adoc
contracts:api:gsn.adoc

gsn-provider/0.1/interacting-with-relayhub
learn::sending-gassless-transactions.adoc

upgrades/2.7/creating-upgradeable-from-solidity
learn::deploy-and-interact.adoc

upgrades/2.6/creating-upgradeable-from-solidity
learn::deploy-and-interact.adoc

upgrades/2.8/creating-upgradeable-from-solidity
learn::deploy-and-interact.adoc

starter-kits/2.3/index
sdk::index.adoc
learn::on-daps.adoc

contracts/3.x-rc/releases-stability
api:drafts.adoc

contracts/3.x-rc/utilities
api:drafts.adoc
721.adoc

contracts/2.x/utilities
721.adoc

contracts/2.x/crowdsales
api:Crowdsale.adoc

cli/2.6/configuration
pattern.adoc
architecture.adoc

cli/2.6/faq
architecture.adoc

cli/2.6/publishing-ethereum-package
learn::public-staging.adoc
learn::on-upgrades.adoc
learn::on-upgrades.adoc
learn::public-staging.adoc

cli/2.6/deploying-with-create2
learn::deploy-and-interact.adoc

cli/2.6/getting-started
learn::deploy-and-interact.adoc

cli/2.7/configuration
pattern.adoc
architecture.adoc

cli/2.6/dependencies
upgrades::writing-contracts.adoc
learn::deploy-and-interact.adoc
learn::mainnet.adoc
writing-contracts.adoc

cli/2.7/faq
architecture.adoc

cli/2.7/publishing-ethereum-package
learn::public-staging.adoc
learn::on-upgrades.adoc
learn::on-upgrades.adoc
learn::public-staging.adoc

cli/2.6/index
using-dependencies.adoc

cli/2.7/dependencies
learn::deploy-and-interact.adoc
learn::mainnet.adoc

cli/2.7/getting-started
learn::deploy-and-interact.adoc

cli/2.7/deploying-with-create2
learn::deploy-and-interact.adoc

cli/2.8/configuration
pattern.adoc
architecture.adoc

cli/2.8/deploying-with-create2
learn::deploy-and-interact.adoc

cli/2.8/dependencies
learn::deploy-and-interact.adoc
learn::mainnet.adoc

cli/2.8/faq
architecture.adoc

cli/2.8/getting-started
learn::deploy-and-interact.adoc

cli/2.8/index
using-dependencies.adoc

cli/2.8/publishing-ethereum-package
learn::public-staging.adoc
learn::on-upgrades.adoc
learn::on-upgrades.adoc
learn::public-staging.adoc

contracts/2.x/api/drafts
ROOT:api-stability.adoc

cli/2.7/index
using-dependencies.adoc