Add short description to each known artifact in artifact size table

Author: Kobzol

site/frontend/src/pages/compare/artifact-size/artifact-size-table.vue

@@ -65,6 +65,29 @@ function getClass(a: number | undefined, b: number | undefined): string {
   }
   return diffClass(b - a);
 }
+
+function generateTitle(component: string): string {
+  if (component === "rustc") {
+    return `Main binary of the Rust compiler. It is a small shim that links to librustc_driver.so,
+ which contains most of the compiler logic.`;
+  } else if (component === "rustdoc") {
+    return `Tool that generates documentation of Rust crates. Links to librustc_driver.so, which provides
+ most of the compiler logic.`;
+  } else if (component === "cargo") {
+    return "Build tool that compiles crates and their dependencies.";
+  } else if (component === "librustc_driver") {
+    return `Shared library which contains the core implementation of the compiler. It is used by several
+ other tools and binaries.`;
+  } else if (component === "libLLVM") {
+    return `LLVM codegen backend that is used by librustc_driver.so to emit optimized assembly.`;
+  } else if (component === "libstd") {
+    return `The Rust standard library.`;
+  } else if (component === "libtest") {
+    return `Library that contains implementation of the default test harness used by Rust programs.`;
+  } else {
+    return ""; // Unknown component
+  }
+}
 </script>
 
 <template>
@@ -81,7 +104,9 @@ function getClass(a: number | undefined, b: number | undefined): string {
     </thead>
     <tbody>
       <tr v-for="component in components">
-        <td class="component">{{ formatName(component) }}</td>
+        <td class="component" :title="generateTitle(component)">
+          {{ formatName(component) }}
+        </td>
         <td>
           <div class="aligned">
             {{ formatValue(a.component_sizes[component]) }}