chore: warn when corpus is empty

Author: sdkrystian

include/mrdocs/Corpus.hpp

@@ -78,6 +78,12 @@ class MRDOCS_VISIBLE
     iterator
     end() const noexcept = 0;
 
+    /** Whether the corpus contains any symbols.
+    */
+    MRDOCS_DECL
+    bool
+    empty() const noexcept;
+
     /** Return the Info with the matching ID, or nullptr.
     */
     MRDOCS_DECL

src/lib/Lib/Corpus.cpp

@@ -28,6 +28,13 @@ Corpus::~Corpus() noexcept = default;
 //
 //------------------------------------------------
 
+bool
+Corpus::
+empty() const noexcept
+{
+    return begin() == end();
+}
+
 /** Return the metadata for the global namespace.
 */
 NamespaceInfo const&

src/tool/GenerateAction.cpp

@@ -114,6 +114,12 @@ DoGenerateAction()
         CorpusImpl::build(
             report::Level::info, config, compilationDatabase));
 
+    if(corpus->empty())
+    {
+        report::warn("Corpus is empty, not generating docs");
+        return {};
+    }
+
     // --------------------------------------------------------------
     //
     // Generate docs