Replace error with warning

Author: joshka

src/cargo/util/toml/mod.rs

@@ -4,7 +4,6 @@ use std::ffi::OsStr;
 use std::path::{Path, PathBuf};
 use std::rc::Rc;
 use std::str::{self, FromStr};
-use tracing_subscriber::fmt::format;
 
 use crate::core::summary::MissingDependencyError;
 use crate::AlreadyPrintedError;
@@ -2145,7 +2144,7 @@ fn to_dependency_source_id<P: ResolveToPath + Clone>(
                 .unwrap_or(GitReference::DefaultBranch);
             let loc = git.into_url()?;
 
-            bail_if_github_pull_request(&name_in_toml, &loc)?;
+            warn_if_github_pull_request(&name_in_toml, &loc, manifest_ctx.warnings);
 
             if let Some(fragment) = loc.fragment() {
                 let msg = format!(
@@ -2187,23 +2186,26 @@ fn to_dependency_source_id<P: ResolveToPath + Clone>(
 
 /// Checks if the URL is a GitHub pull request URL.
 ///
-/// If the URL is a GitHub pull request URL, an error is returned with a message that explains
-/// how to specify a specific git revision.
-fn bail_if_github_pull_request(name_in_toml: &str, url: &Url) -> CargoResult<()> {
+/// If the URL is a GitHub pull request URL, an warning is emitted with a message that explains how
+/// to specify a specific git revision.
+///
+/// At some point in the future it might be worth considering making this a hard error, but for now
+/// it's just a warning. See <https://github.com/rust-lang/cargo/pull/15003#discussion_r1908005924>.
+fn warn_if_github_pull_request(name_in_toml: &str, url: &Url, warnings: &mut Vec<String>) {
     if url.host_str() != Some("github.com") {
-        return Ok(());
+        return;
     }
     let path_components = url.path().split('/').collect::<Vec<_>>();
     if let ["", owner, repo, "pull", pr_number, ..] = path_components[..] {
         let repo_url = format!("https://github.com/{owner}/{repo}.git");
         let rev = format!("refs/pull/{pr_number}/head");
-        bail!(
+        let warning = format!(
             "dependency ({name_in_toml}) git url {url} is not a repository. \
                 The path looks like a pull request. Try replacing the dependency with: \
                 `git = \"{repo_url}\" rev = \"{rev}\"` in the dependency declaration.",
         );
+        warnings.push(warning);
     }
-    Ok(())
 }
 
 pub(crate) fn lookup_path_base<'a>(

tests/testsuite/bad_config.rs

@@ -2173,10 +2173,29 @@ fn github_pull_request_url() {
     p.cargo("check -v")
         .with_status(101)
         .with_stderr_data(str![[r#"
-[ERROR] failed to parse manifest at `[ROOT]/foo/Cargo.toml`
+[WARNING] dependency (bar) git url https://github.com/foo/bar/pull/123 is not a repository. The path looks like a pull request. Try replacing the dependency with: `git = "https://github.com/foo/bar.git" rev = "refs/pull/123/head"` in the dependency declaration.
+[UPDATING] git repository `https://github.com/foo/bar/pull/123`
+[WARNING] spurious network error (3 tries remaining): unexpected http status code: 404; class=Http (34)
+[WARNING] spurious network error (2 tries remaining): unexpected http status code: 404; class=Http (34)
+[WARNING] spurious network error (1 tries remaining): unexpected http status code: 404; class=Http (34)
+[ERROR] failed to get `bar` as a dependency of package `foo v0.0.0 ([ROOT]/foo)`
+
+Caused by:
+  failed to load source for dependency `bar`
+
+Caused by:
+  Unable to update https://github.com/foo/bar/pull/123
+
+Caused by:
+  failed to clone into: [ROOT]/home/.cargo/git/db/123-[HASH]
+
+Caused by:
+  network failure seems to have happened
+  if a proxy or similar is necessary `net.git-fetch-with-cli` may help here
+  https://doc.rust-lang.org/cargo/reference/config.html#netgit-fetch-with-cli
 
 Caused by:
-  dependency (bar) git url https://github.com/foo/bar/pull/123 is not a repository. The path looks like a pull request. Try replacing the dependency with: `git = "https://github.com/foo/bar.git" rev = "refs/pull/123/head"` in the dependency declaration.
+  unexpected http status code: 404; class=Http (34)
 
 "#]])
         .run();