bootstrap: don't build redirect pages during dry-run/test

Author: jieyouxu

src/bootstrap/src/core/build_steps/doc.rs

@@ -274,6 +274,10 @@ impl Step for TheBook {
 
         // build the redirect pages
         let _guard = builder.msg(Kind::Doc, "book redirect pages", None, build_compiler, target);
+        if builder.config.dry_run() {
+            return;
+        }
+
         for file in t!(fs::read_dir(redirect_path)) {
             let file = t!(file);
             let path = file.path();

src/bootstrap/src/core/builder/tests.rs

@@ -1537,8 +1537,8 @@ mod snapshot {
         [doc] book/first-edition (book) <target1>
         [doc] book/second-edition (book) <target1>
         [doc] book/2018-edition (book) <target1>
-        [build] rustdoc 1 <host>
         [build] rustc 1 <host> -> std 1 <host>
+        [build] rustdoc 1 <host>
         [doc] rustc 1 <host> -> standalone 2 <target1>
         [doc] rustc 1 <host> -> std 1 <target1> crates=[alloc,compiler_builtins,core,panic_abort,panic_unwind,proc_macro,rustc-std-workspace-core,std,std_detect,sysroot,test,unwind]
         [build] llvm <target1>