rustdoc: make --emit and --out-dir mimic rustc

The behavior in the test case matches rustc's:

    test-dingus % ls
    main.rs
    test-dingus % mkdir foobar
    test-dingus % rustc --emit=dep-info main.rs --out-dir=foobar
    test-dingus % ls
    foobar  main.rs
    test-dingus % ls foobar
    main.d
    test-dingus % rustc --emit=dep-info=testfile.d main.rs --out-dir=foobar
    test-dingus % ls
    foobar          main.rs         testfile.d
    test-dingus % ls foobar
    main.d

Author: notriddle

src/librustdoc/core.rs

@@ -285,7 +285,11 @@ pub(crate) fn create_config(
         crate_check_cfg: check_cfgs,
         input,
         output_file: None,
-        output_dir: None,
+        output_dir: if render_options.output_to_stdout {
+            None
+        } else {
+            Some(render_options.output.clone())
+        },
         file_loader: None,
         lint_caps,
         psess_created: None,

src/librustdoc/lib.rs

@@ -68,6 +68,7 @@ extern crate test;
 extern crate tikv_jemalloc_sys as _;
 
 use std::env::{self, VarError};
+use std::fs;
 use std::io::{self, IsTerminal};
 use std::path::Path;
 use std::process::ExitCode;
@@ -932,6 +933,10 @@ fn main_args(early_dcx: &mut EarlyDiagCtxt, at_args: &[String]) {
             }
 
             if render_opts.dep_info().is_some() {
+                if let Err(e) = fs::create_dir_all(&render_opts.output) {
+                    sess.dcx()
+                        .fatal(format!("{output}: {e}", output = render_opts.output.display()));
+                }
                 rustc_interface::passes::write_dep_info(tcx);
             }
 

tests/run-make/rustdoc-dep-info/rmake.rs

@@ -20,7 +20,7 @@ fn main() {
         .emit("dep-info")
         .run();
 
-    let content = rfs::read_to_string("foo.d");
+    let content = rfs::read_to_string("doc/foo.d");
     assert_contains(&content, "lib.rs:");
     assert_contains(&content, "foo.rs:");
     assert_contains(&content, "bar.rs:");

tests/run-make/rustdoc-scrape-examples-dep-info/rmake.rs

@@ -10,10 +10,10 @@ fn main() {
         &["--emit=dep-info,invocation-specific"],
     );
 
-    let content = rfs::read_to_string("foobar.d").replace(r"\", "/");
+    let content = rfs::read_to_string("rustdoc/foobar.d").replace(r"\", "/");
     assert_contains(&content, "lib.rs:");
     assert_contains(&content, "rustdoc/ex.calls:");
 
-    let content = rfs::read_to_string("ex.d").replace(r"\", "/");
+    let content = rfs::read_to_string("rustdoc/ex.d").replace(r"\", "/");
     assert_contains(&content, "examples/ex.rs:");
 }