Add a disable-minification option for rustdoc

This way, you can debug rustdoc's JavaScript and CSS file
with normal F12 Dev Tools and you'll have useful line numbers
to work with.

config.toml.example

@@ -208,6 +208,11 @@ changelog-seen = 2
 # documentation.
 #docs = true
 
+# Flag to specify whether CSS, JavaScript, and HTML are minified when
+# docs are generated. JSON is always minified, because it's enormous,
+# and generated in already-minified form from the beginning.
+#docs-minification = true
+
 # Indicate whether the compiler should be documented in addition to the standard
 # library and facade crates.
 #compiler-docs = false

src/bootstrap/config.rs

@@ -51,6 +51,7 @@ pub struct Config {
     pub submodules: bool,
     pub fast_submodules: bool,
     pub compiler_docs: bool,
+    pub docs_minification: bool,
     pub docs: bool,
     pub locked_deps: bool,
     pub vendor: bool,
@@ -362,6 +363,7 @@ struct Build {
     rustfmt: Option<PathBuf>,
     docs: Option<bool>,
     compiler_docs: Option<bool>,
+    docs_minification: Option<bool>,
     submodules: Option<bool>,
     fast_submodules: Option<bool>,
     gdb: Option<String>,
@@ -663,6 +665,7 @@ impl Config {
         config.python = build.python.map(PathBuf::from);
         set(&mut config.low_priority, build.low_priority);
         set(&mut config.compiler_docs, build.compiler_docs);
+        set(&mut config.docs_minification, build.docs_minification);
         set(&mut config.docs, build.docs);
         set(&mut config.submodules, build.submodules);
         set(&mut config.fast_submodules, build.fast_submodules);

src/bootstrap/doc.rs

@@ -270,6 +270,10 @@ fn invoke_rustdoc(
         .arg("--markdown-css")
         .arg("../rust.css");
 
+    if !builder.config.docs_minification {
+        cmd.arg("-Z").arg("unstable-options").arg("--disable-minification");
+    }
+
     builder.run(&mut cmd);
 }
 
@@ -365,6 +369,10 @@ impl Step for Standalone {
                 .arg(&out)
                 .arg(&path);
 
+            if !builder.config.docs_minification {
+                cmd.arg("--disable-minification");
+            }
+
             if filename == "not_found.md" {
                 cmd.arg("--markdown-css").arg("https://doc.rust-lang.org/rust.css");
             } else {
@@ -437,6 +445,10 @@ impl Step for Std {
                 .arg("--index-page")
                 .arg(&builder.src.join("src/doc/index.md"));
 
+            if !builder.config.docs_minification {
+                cargo.arg("--disable-minification");
+            }
+
             builder.run(&mut cargo.into());
         };
         // Only build the following crates. While we could just iterate over the