Rollup merge of #139863 - fmease:simp-doctest-build-arg-passing, r=GuillaumeGomez

rustdoc: Replace unstable flag `--doctest-compilation-args` with a simpler one: `--doctest-build-arg`

Tracking issue: https://github.com/rust-lang/rust/issues/134172.
Context: https://github.com/rust-lang/rust/pull/137096#issuecomment-2776318800

Yeets the ad hoc shell-like lexer for 'nested' program arguments.
No FCP necessary since the flag is unstable.

I've chosen to replace `compilation` with `build` because it's shorter (you now need to pass it multiple times in order to pass many arguments to the doctest compiler, so it matters a bit) and since I prefer it esthetically.

**Issue**: Even though we don't process the argument passed to `--doctest-build-arg`, we end up passing it via an argument file (`rustc `@argfile`)` which delimits arguments by line break (LF or CRLF, [via](https://doc.rust-lang.org/rustc/command-line-arguments.html#path-load-command-line-flags-from-a-path)) meaning ultimately the arguments still get split which is unfortunate. Still, I think this change is an improvement over the status quo.

I'll update the tracking issue if/once this PR merges. I'll also add the (CR)LF issue to 'unresolved question'.

r? GuillaumeGomez
r? notriddle

8 files changed, 15 insertions, 79 deletions

diff --git a/src/librustdoc/config.rs b/src/librustdoc/config.rs
index 4ef73ff48ed..f93aa8ffd0d 100644
--- a/src/librustdoc/config.rs
+++ b/src/librustdoc/config.rs
@@ -174,7 +174,7 @@ pub(crate) struct Options {
     pub(crate) expanded_args: Vec<String>,
 
     /// Arguments to be used when compiling doctests.
-    pub(crate) doctest_compilation_args: Vec<String>,
+    pub(crate) doctest_build_args: Vec<String>,
 }
 
 impl fmt::Debug for Options {
@@ -802,7 +802,7 @@ impl Options {
         let scrape_examples_options = ScrapeExamplesOptions::new(matches, dcx);
         let with_examples = matches.opt_strs("with-examples");
         let call_locations = crate::scrape_examples::load_call_locations(with_examples, dcx);
-        let doctest_compilation_args = matches.opt_strs("doctest-compilation-args");
+        let doctest_build_args = matches.opt_strs("doctest-build-arg");
 
         let unstable_features =
             rustc_feature::UnstableFeatures::from_environment(crate_name.as_deref());
@@ -851,7 +851,7 @@ impl Options {
             scrape_examples_options,
             unstable_features,
             expanded_args: args,
-            doctest_compilation_args,
+            doctest_build_args,
         };
         let render_options = RenderOptions {
             output,
diff --git a/src/librustdoc/doctest.rs b/src/librustdoc/doctest.rs
index 0cdf2f92a89..ef70b862185 100644
--- a/src/librustdoc/doctest.rs
+++ b/src/librustdoc/doctest.rs
@@ -51,46 +51,6 @@ pub(crate) struct GlobalTestOptions {
     pub(crate) args_file: PathBuf,
 }
 
-/// Function used to split command line arguments just like a shell would.
-fn split_args(args: &str) -> Vec<String> {
-    let mut out = Vec::new();
-    let mut iter = args.chars();
-    let mut current = String::new();
-
-    while let Some(c) = iter.next() {
-        if c == '\\' {
-            if let Some(c) = iter.next() {
-                // If it's escaped, even a quote or a whitespace will be ignored.
-                current.push(c);
-            }
-        } else if c == '"' || c == '\'' {
-            while let Some(new_c) = iter.next() {
-                if new_c == c {
-                    break;
-                } else if new_c == '\\' {
-                    if let Some(c) = iter.next() {
-                        // If it's escaped, even a quote will be ignored.
-                        current.push(c);
-                    }
-                } else {
-                    current.push(new_c);
-                }
-            }
-        } else if " \n\t\r".contains(c) {
-            if !current.is_empty() {
-                out.push(current.clone());
-                current.clear();
-            }
-        } else {
-            current.push(c);
-        }
-    }
-    if !current.is_empty() {
-        out.push(current);
-    }
-    out
-}
-
 pub(crate) fn generate_args_file(file_path: &Path, options: &RustdocOptions) -> Result<(), String> {
     let mut file = File::create(file_path)
         .map_err(|error| format!("failed to create args file: {error:?}"))?;
@@ -119,9 +79,7 @@ pub(crate) fn generate_args_file(file_path: &Path, options: &RustdocOptions) ->
         content.push(format!("-Z{unstable_option_str}"));
     }
 
-    for compilation_args in &options.doctest_compilation_args {
-        content.extend(split_args(compilation_args));
-    }
+    content.extend(options.doctest_build_args.clone());
 
     let content = content.join("\n");
 
diff --git a/src/librustdoc/doctest/tests.rs b/src/librustdoc/doctest/tests.rs
index 49add73e9d6..618c2041b43 100644
--- a/src/librustdoc/doctest/tests.rs
+++ b/src/librustdoc/doctest/tests.rs
@@ -382,28 +382,6 @@ fn main() {
 }
 
 #[test]
-fn check_split_args() {
-    fn compare(input: &str, expected: &[&str]) {
-        let output = super::split_args(input);
-        let expected = expected.iter().map(|s| s.to_string()).collect::<Vec<_>>();
-        assert_eq!(expected, output, "test failed for {input:?}");
-    }
-
-    compare("'a' \"b\"c", &["a", "bc"]);
-    compare("'a' \"b \"c d", &["a", "b c", "d"]);
-    compare("'a' \"b\\\"c\"", &["a", "b\"c"]);
-    compare("'a\"'", &["a\""]);
-    compare("\"a'\"", &["a'"]);
-    compare("\\ a", &[" a"]);
-    compare("\\\\", &["\\"]);
-    compare("a'", &["a"]);
-    compare("a          ", &["a"]);
-    compare("a          b", &["a", "b"]);
-    compare("a\n\t \rb", &["a", "b"]);
-    compare("a\n\t1 \rb", &["a", "1", "b"]);
-}
-
-#[test]
 fn comment_in_attrs() {
     // If there is an inline code comment after attributes, we need to ensure that
     // a backline will be added to prevent generating code "inside" it (and thus generating)
diff --git a/src/librustdoc/lib.rs b/src/librustdoc/lib.rs
index bca40b8117b..fd1c89d91bd 100644
--- a/src/librustdoc/lib.rs
+++ b/src/librustdoc/lib.rs
@@ -654,9 +654,9 @@ fn opts() -> Vec<RustcOptGroup> {
             Unstable,
             Multi,
             "",
-            "doctest-compilation-args",
-            "",
-            "add arguments to be used when compiling doctests",
+            "doctest-build-arg",
+            "One argument (of possibly many) to be used when compiling doctests",
+            "ARG",
         ),
         opt(
             Unstable,
diff --git a/tests/run-make/rustdoc-default-output/output-default.stdout b/tests/run-make/rustdoc-default-output/output-default.stdout
index 78ca8c863eb..506f135ff8e 100644
--- a/tests/run-make/rustdoc-default-output/output-default.stdout
+++ b/tests/run-make/rustdoc-default-output/output-default.stdout
@@ -188,8 +188,9 @@ Options:
                         from provided path. Only use with --merge=finalize
         --html-no-source 
                         Disable HTML source code pages generation
-        --doctest-compilation-args add arguments to be used when compiling doctests
-                        
+        --doctest-build-arg ARG
+                        One argument (of possibly many) to be used when
+                        compiling doctests
         --disable-minification 
                         disable the minification of CSS/JS files
                         (perma-unstable, do not use with cached files)
diff --git a/tests/rustdoc-ui/doctest/rustflags-multiple-args.rs b/tests/rustdoc-ui/doctest/rustflags-multiple-args.rs
index 8d8c60ede58..88e2e0cf019 100644
--- a/tests/rustdoc-ui/doctest/rustflags-multiple-args.rs
+++ b/tests/rustdoc-ui/doctest/rustflags-multiple-args.rs
@@ -1,9 +1,8 @@
-// This test checks that the test behave when `--doctest-compilation-args` is passed
-// multiple times.
+// This test checks that the test behave when `--doctest-build-arg` is passed multiple times.
 
 //@ check-pass
-//@ compile-flags: --test -Zunstable-options --doctest-compilation-args=--cfg=testcase_must_be_present
-//@ compile-flags: --doctest-compilation-args=--cfg=another
+//@ compile-flags: --test -Zunstable-options --doctest-build-arg=--cfg=testcase_must_be_present
+//@ compile-flags: --doctest-build-arg=--cfg=another
 //@ normalize-stdout: "tests/rustdoc-ui/doctest" -> "$$DIR"
 //@ normalize-stdout: "finished in \d+\.\d+s" -> "finished in $$TIME"
 
diff --git a/tests/rustdoc-ui/doctest/rustflags-multiple-args.stdout b/tests/rustdoc-ui/doctest/rustflags-multiple-args.stdout
index 0e8a9e1efcf..f6b8ad6afab 100644
--- a/tests/rustdoc-ui/doctest/rustflags-multiple-args.stdout
+++ b/tests/rustdoc-ui/doctest/rustflags-multiple-args.stdout
@@ -1,6 +1,6 @@
 
 running 1 test
-test $DIR/rustflags-multiple-args.rs - Bar (line 10) ... ok
+test $DIR/rustflags-multiple-args.rs - Bar (line 9) ... ok
 
 test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in $TIME
 
diff --git a/tests/rustdoc-ui/doctest/rustflags.rs b/tests/rustdoc-ui/doctest/rustflags.rs
index 9f1e6017ea1..f030158cdaa 100644
--- a/tests/rustdoc-ui/doctest/rustflags.rs
+++ b/tests/rustdoc-ui/doctest/rustflags.rs
@@ -1,5 +1,5 @@
 //@ check-pass
-//@ compile-flags: --test -Zunstable-options --doctest-compilation-args=--cfg=testcase_must_be_present
+//@ compile-flags: --test -Zunstable-options --doctest-build-arg=--cfg=testcase_must_be_present
 //@ normalize-stdout: "tests/rustdoc-ui/doctest" -> "$$DIR"
 //@ normalize-stdout: "finished in \d+\.\d+s" -> "finished in $$TIME"