Add test for rules_rust#1952

Adds a test that reproduces the bug mentioned in rules_rust#1952.

test/unit/rustdoc/procmacro_in_rustdoc.rs

@@ -0,0 +1,9 @@
+/// A different answer that only exists if using procmacros.
+/// ```
+/// use rustdoc_proc_macro::make_answer;
+/// make_answer!();
+/// assert_eq!(answer(), 42);
+/// ```
+pub fn procmacro_answer() -> u32 {
+    24
+}

test/unit/rustdoc/rustdoc_unit_test.bzl

@@ -74,6 +74,14 @@ def _rustdoc_for_lib_with_proc_macro_test_impl(ctx):
 
     return analysistest.end(env)
 
+def _rustdoc_for_lib_with_proc_macro_in_docs_test_impl(ctx):
+    env = analysistest.begin(ctx)
+    tut = analysistest.target_under_test(env)
+
+    _common_rustdoc_checks(env, tut)
+
+    return analysistest.end(env)
+
 def _rustdoc_for_bin_with_transitive_proc_macro_test_impl(ctx):
     env = analysistest.begin(ctx)
     tut = analysistest.target_under_test(env)
@@ -145,6 +153,7 @@ rustdoc_for_bin_with_cc_lib_test = analysistest.make(_rustdoc_for_bin_with_cc_li
 rustdoc_for_bin_with_transitive_cc_lib_test = analysistest.make(_rustdoc_for_bin_with_transitive_cc_lib_test_impl)
 rustdoc_for_proc_macro_test = analysistest.make(_rustdoc_for_proc_macro_test_impl)
 rustdoc_for_lib_with_proc_macro_test = analysistest.make(_rustdoc_for_lib_with_proc_macro_test_impl)
+rustdoc_for_lib_with_proc_macro_in_docs_test = analysistest.make(_rustdoc_for_lib_with_proc_macro_in_docs_test_impl)
 rustdoc_for_bin_with_transitive_proc_macro_test = analysistest.make(_rustdoc_for_bin_with_transitive_proc_macro_test_impl)
 rustdoc_for_lib_with_cc_lib_test = analysistest.make(_rustdoc_for_lib_with_cc_lib_test_impl)
 rustdoc_with_args_test = analysistest.make(_rustdoc_with_args_test_impl)
@@ -234,6 +243,13 @@ def _define_targets():
         crate_features = ["with_proc_macro"],
     )
 
+    _target_maker(
+        rust_library,
+        name = "lib_with_proc_macro_in_docs",
+        srcs = ["procmacro_in_rustdoc.rs"],
+        proc_macro_deps = [":rustdoc_proc_macro"],
+    )
+
     _target_maker(
         rust_library,
         name = "lib_nodep_with_proc_macro",
@@ -371,6 +387,11 @@ def rustdoc_test_suite(name):
         target_under_test = ":rustdoc_proc_macro_doc",
     )
 
+    rustdoc_for_lib_with_proc_macro_in_docs_test(
+        name = "rustdoc_for_lib_with_proc_macro_in_docs_test",
+        target_under_test = ":lib_with_proc_macro_in_docs_doc",
+    )
+
     rustdoc_for_lib_with_proc_macro_test(
         name = "rustdoc_for_lib_with_proc_macro_test",
         target_under_test = ":lib_with_proc_macro_doc",
@@ -414,6 +435,7 @@ def rustdoc_test_suite(name):
             ":rustdoc_for_bin_with_cc_lib_test",
             ":rustdoc_for_bin_with_transitive_cc_lib_test",
             ":rustdoc_for_proc_macro_test",
+            ":rustdoc_for_lib_with_proc_macro_in_docs_test",
             ":rustdoc_for_lib_with_proc_macro_test",
             ":rustdoc_for_lib_with_cc_lib_test",
             ":rustdoc_with_args_test",