feat(tree): Color the output (#15242)

### What does this PR try to resolve?

This is an experiment to find ways to make `cargo tree` output easier to
grok. I find too many details are hard to spot because everything looks
the same.

![image](https://github.com/user-attachments/assets/92055027-c7a0-4357-9870-400ba6c2de9c)

The goal is to make it easier to scan the output for relevant details.
So far, this approach seems the most viable. Knowing what type of edges
led to where you are provides useful context for scrolling through large
lists of dependencies.

Fixes #10558

### How should we test and review this PR?

I had considered styling normal dependency edges but there isn't a
header to clarify what they mean, so I decided to match the package name
as that is the header. So this didn't buy as much as I had hoped,
especially since dimmed lines aren't obvious with my terminal. Maybe if
we used different unicode graph characters.

Instead of coloring the "this is elided" `(*)`, I had considered using a
unicode character that looks like its pointing from that item up. I only
found one that looked close to that but the origin for the arrow was
bottom aligned, rather than center aligned and it looked off.

Alternatives considered
- Once an edge is marked with dev or build dependencies, all future
edges inherit it
- While this makes it clear what section you are in, so does the outer
most line
- Feature edges are the color of the edges that led to them
  - Unsure of value either way
  - This might get weird with `--invert`
- Style local nodes different than non-local
- With the format string being user customizable, I'm concerned with
styling over or within user styling
- Rainbow packages: For every package in the same namespace
(`.split_once("::").0`) or prefix (`.split_once(['-','_']).0`), assign a
color (maybe only for the top N packages to reduce duplicate colors)
  - Would help a lot with `gix-*` and similar other cases
- If we cap the number of participating packages, would need care to
work with `--depth`

(of course,. these could be mixed)

### Additional information

Author: weihanglo

src/cargo/ops/tree/mod.rs

@@ -300,26 +300,31 @@ fn print_node<'a>(
     no_dedupe: bool,
     display_depth: DisplayDepth,
     visited_deps: &mut HashSet<NodeId>,
-    levels_continue: &mut Vec<bool>,
+    levels_continue: &mut Vec<(anstyle::Style, bool)>,
     print_stack: &mut Vec<NodeId>,
 ) {
     let new = no_dedupe || visited_deps.insert(node_index);
 
     match prefix {
         Prefix::Depth => drop_print!(ws.gctx(), "{}", levels_continue.len()),
         Prefix::Indent => {
-            if let Some((last_continues, rest)) = levels_continue.split_last() {
-                for continues in rest {
+            if let Some(((last_style, last_continues), rest)) = levels_continue.split_last() {
+                for (style, continues) in rest {
                     let c = if *continues { symbols.down } else { " " };
-                    drop_print!(ws.gctx(), "{}   ", c);
+                    drop_print!(ws.gctx(), "{style}{c}{style:#}   ");
                 }
 
                 let c = if *last_continues {
                     symbols.tee
                 } else {
                     symbols.ell
                 };
-                drop_print!(ws.gctx(), "{0}{1}{1} ", c, symbols.right);
+                drop_print!(
+                    ws.gctx(),
+                    "{last_style}{0}{1}{1}{last_style:#} ",
+                    c,
+                    symbols.right
+                );
             }
         }
         Prefix::None => {}
@@ -333,7 +338,7 @@ fn print_node<'a>(
     let star = if (new && !in_cycle) || !has_deps {
         ""
     } else {
-        " (*)"
+        color_print::cstr!(" <yellow,dim>(*)</>")
     };
     drop_println!(ws.gctx(), "{}{}", format.display(graph, node_index), star);
 
@@ -379,7 +384,7 @@ fn print_dependencies<'a>(
     no_dedupe: bool,
     display_depth: DisplayDepth,
     visited_deps: &mut HashSet<NodeId>,
-    levels_continue: &mut Vec<bool>,
+    levels_continue: &mut Vec<(anstyle::Style, bool)>,
     print_stack: &mut Vec<NodeId>,
     kind: &EdgeKind,
 ) {
@@ -390,19 +395,23 @@ fn print_dependencies<'a>(
 
     let name = match kind {
         EdgeKind::Dep(DepKind::Normal) => None,
-        EdgeKind::Dep(DepKind::Build) => Some("[build-dependencies]"),
-        EdgeKind::Dep(DepKind::Development) => Some("[dev-dependencies]"),
+        EdgeKind::Dep(DepKind::Build) => {
+            Some(color_print::cstr!("<blue,bold>[build-dependencies]</>"))
+        }
+        EdgeKind::Dep(DepKind::Development) => {
+            Some(color_print::cstr!("<cyan,bold>[dev-dependencies]</>"))
+        }
         EdgeKind::Feature => None,
     };
 
     if let Prefix::Indent = prefix {
         if let Some(name) = name {
-            for continues in &**levels_continue {
+            for (style, continues) in &**levels_continue {
                 let c = if *continues { symbols.down } else { " " };
-                drop_print!(ws.gctx(), "{}   ", c);
+                drop_print!(ws.gctx(), "{style}{c}{style:#}   ");
             }
 
-            drop_println!(ws.gctx(), "{}", name);
+            drop_println!(ws.gctx(), "{name}");
         }
     }
 
@@ -433,7 +442,8 @@ fn print_dependencies<'a>(
         .peekable();
 
     while let Some(dependency) = it.next() {
-        levels_continue.push(it.peek().is_some());
+        let style = edge_line_color(dependency.kind());
+        levels_continue.push((style, it.peek().is_some()));
         print_node(
             ws,
             graph,
@@ -451,3 +461,16 @@ fn print_dependencies<'a>(
         levels_continue.pop();
     }
 }
+
+fn edge_line_color(kind: EdgeKind) -> anstyle::Style {
+    match kind {
+        EdgeKind::Dep(DepKind::Normal) => anstyle::Style::new() | anstyle::Effects::DIMMED,
+        EdgeKind::Dep(DepKind::Build) => {
+            anstyle::AnsiColor::Blue.on_default() | anstyle::Effects::BOLD
+        }
+        EdgeKind::Dep(DepKind::Development) => {
+            anstyle::AnsiColor::Cyan.on_default() | anstyle::Effects::BOLD
+        }
+        EdgeKind::Feature => anstyle::AnsiColor::Magenta.on_default() | anstyle::Effects::DIMMED,
+    }
+}

tests/testsuite/tree.rs renamed to tests/testsuite/cargo_tree/deps.rs

@@ -6,7 +6,7 @@ use cargo_test_support::registry::{Dependency, Package};
 use cargo_test_support::str;
 use cargo_test_support::{basic_manifest, git, project, rustc_host, Project};
 
-use super::features2::switch_to_resolver_2;
+use crate::features2::switch_to_resolver_2;
 
 fn make_simple_proj() -> Project {
     Package::new("c", "1.0.0").publish();

tests/testsuite/cargo_tree/dupe/mod.rs

@@ -0,0 +1,36 @@
+use cargo_test_support::file;
+use cargo_test_support::prelude::*;
+use cargo_test_support::project;
+use cargo_test_support::registry::Package;
+
+#[cargo_test]
+fn case() {
+    Package::new("a", "1.0.0").dep("b", "1.0").publish();
+    Package::new("b", "1.0.0").dep("c", "1.0").publish();
+    Package::new("c", "1.0.0").publish();
+
+    let p = project()
+        .file(
+            "Cargo.toml",
+            r#"
+            [package]
+            name = "foo"
+            version = "0.1.0"
+
+            [dependencies]
+            a = "1.0"
+            b = "1.0"
+            "#,
+        )
+        .file("src/lib.rs", "")
+        .file("build.rs", "fn main() {}")
+        .build();
+
+    snapbox::cmd::Command::cargo_ui()
+        .arg("tree")
+        .current_dir(p.root())
+        .assert()
+        .success()
+        .stdout_eq(file!["stdout.term.svg"])
+        .stderr_eq(file!["stderr.term.svg"]);
+}

tests/testsuite/cargo_tree/dupe/stderr.term.svg

@@ -0,0 +1,100 @@
+use cargo_test_support::file;
+use cargo_test_support::prelude::*;
+use cargo_test_support::project;
+use cargo_test_support::registry::Package;
+
+#[cargo_test]
+fn case() {
+    Package::new("normal_a", "1.0.0")
+        .dep("normal_b", "1.0")
+        .publish();
+    Package::new("normal_b", "1.0.0")
+        .dep("normal_c", "1.0")
+        .build_dep("normal_b_build_a", "1.0.0")
+        .dev_dep("normal_b_dev_a", "1.0.0")
+        .publish();
+    Package::new("normal_c", "1.0.0").publish();
+    Package::new("normal_b_build_a", "1.0.0")
+        .dep("normal_b_build_a_normal_a", "1.0.0")
+        .publish();
+    Package::new("normal_b_build_a_normal_a", "1.0.0").publish();
+    Package::new("normal_b_dev_a", "1.0.0")
+        .dep("normal_b_dev_a_normal_a", "1.0.0")
+        .publish();
+    Package::new("normal_b_dev_a_normal_a", "1.0.0").publish();
+    Package::new("normal_d", "1.0.0").publish();
+
+    Package::new("build_a", "1.0.0")
+        .dep("build_b", "1.0")
+        .publish();
+    Package::new("build_b", "1.0.0")
+        .dep("build_c", "1.0")
+        .build_dep("build_b_build_a", "1.0.0")
+        .dev_dep("build_b_dev_a", "1.0.0")
+        .publish();
+    Package::new("build_c", "1.0.0").publish();
+    Package::new("build_b_build_a", "1.0.0")
+        .dep("build_b_build_a_normal_a", "1.0.0")
+        .publish();
+    Package::new("build_b_build_a_normal_a", "1.0.0").publish();
+    Package::new("build_b_dev_a", "1.0.0")
+        .dep("build_b_dev_a_normal_a", "1.0.0")
+        .publish();
+    Package::new("build_b_dev_a_normal_a", "1.0.0").publish();
+    Package::new("build_d", "1.0.0").publish();
+
+    Package::new("dev_a", "1.0.0").dep("dev_b", "1.0").publish();
+    Package::new("dev_b", "1.0.0")
+        .dep("dev_c", "1.0")
+        .build_dep("dev_b_build_a", "1.0.0")
+        .dev_dep("dev_b_dev_a", "1.0.0")
+        .publish();
+    Package::new("dev_c", "1.0.0").publish();
+    Package::new("dev_b_build_a", "1.0.0")
+        .dep("dev_b_build_a_normal_a", "1.0.0")
+        .publish();
+    Package::new("dev_b_build_a_normal_a", "1.0.0").publish();
+    Package::new("dev_b_dev_a", "1.0.0")
+        .dep("dev_b_dev_a_normal_a", "1.0.0")
+        .publish();
+    Package::new("dev_b_dev_a_normal_a", "1.0.0").publish();
+    Package::new("dev_d", "1.0.0").publish();
+
+    let p = project()
+        .file(
+            "Cargo.toml",
+            r#"
+            [package]
+            name = "foo"
+            version = "0.1.0"
+
+            [features]
+            default = ["foo"]
+            foo = ["dep:normal_a"]
+
+            [dependencies]
+            normal_a = { version = "1.0", optional = true }
+            normal_d = "1.0"
+
+            [build-dependencies]
+            build_a = "1.0"
+            build_d = "1.0"
+
+            [dev-dependencies]
+            dev_a = "1.0"
+            dev_d = "1.0"
+            "#,
+        )
+        .file("src/lib.rs", "")
+        .file("build.rs", "fn main() {}")
+        .build();
+
+    snapbox::cmd::Command::cargo_ui()
+        .arg("tree")
+        .arg("--edges=features")
+        .current_dir(p.root())
+        .assert()
+        .success()
+        .stdout_eq(file!["stdout.term.svg"])
+        .stderr_eq(file!["stderr.term.svg"]);
+}