Auto merge of #8297 - mjarkk:warn-when-using-hash-in-git-url, r=ehuss

Warn if using hash in git URL, Fixes #8241

This fixes an issue where if the user wants to set the git rev but doesn't know how and as results tries to set the ref in the url hash as also shown when downloading the dependency.
Now cargo returns a warning notifying the user about the correct way to set the ref.

Fixes #8241

src/cargo/util/toml/mod.rs

@@ -1661,6 +1661,17 @@ impl DetailedTomlDependency {
                     .or_else(|| self.rev.clone().map(GitReference::Rev))
                     .unwrap_or_else(|| GitReference::Branch("master".to_string()));
                 let loc = git.into_url()?;
+
+                if let Some(fragment) = loc.fragment() {
+                    let msg = format!(
+                        "URL fragment `#{}` in git URL is ignored for dependency ({}). \
+                        If you were trying to specify a specific git revision, \
+                        use `rev = \"{}\"` in the dependency declaration.",
+                        fragment, name_in_toml, fragment
+                    );
+                    cx.warnings.push(msg)
+                }
+
                 SourceId::for_git(&loc, reference)?
             }
             (None, Some(path), _, _) => {

tests/testsuite/bad_config.rs

@@ -861,6 +861,36 @@ This will be considered an error in future versions
         .run();
 }
 
+#[cargo_test]
+fn fragment_in_git_url() {
+    let p = project()
+        .file(
+            "Cargo.toml",
+            r#"
+            [package]
+            name = "foo"
+            version = "0.0.0"
+            authors = []
+
+            [dependencies.bar]
+            git = "http://127.0.0.1#foo"
+        "#,
+        )
+        .file("src/lib.rs", "")
+        .build();
+
+    p.cargo("build -v")
+        .with_status(101)
+        .with_stderr_contains(
+            "\
+[WARNING] URL fragment `#foo` in git URL is ignored for dependency (bar). \
+If you were trying to specify a specific git revision, \
+use `rev = \"foo\"` in the dependency declaration.
+",
+        )
+        .run();
+}
+
 #[cargo_test]
 fn bad_source_config1() {
     let p = project()