feat: support anonymous union members

include/mrdocs/Metadata/Field.hpp

@@ -38,6 +38,9 @@ struct FieldInfo
     */
     ExprInfo Default;
 
+    /** Whether the field is a variant member */
+    bool IsVariant = false;
+
     /** Whether the field is declared mutable */
     bool IsMutable = false;
 

share/mrdocs/addons/generator/asciidoc/partials/special-name-suffix.adoc.hbs

@@ -1,6 +1,8 @@
 {{#if (eq kind "overload")}}{{>special-name-suffix (front members)~}}
 {{else if (eq kind "function")~}}
 {{#if (eq class "constructor")}}[.small]#[constructor]#
-{{~else if (eq class "destructor")~}}[.small]#[destructor]#
+{{~else if (eq class "destructor")}}[.small]#[destructor]#
 {{~/if~}}
+{{else if (eq kind "field")~}}
+{{#if isVariant}}[.small]#[variant member]#{{/if~}}
 {{/if}}

src/lib/AST/ASTVisitor.cpp

@@ -547,6 +547,11 @@ class ASTVisitor
             if(DC->isFileContext() ||
                 DC->isFunctionOrMethod())
                 break;
+
+            if(auto* RD = dyn_cast<CXXRecordDecl>(DC);
+                RD && RD->isAnonymousStructOrUnion())
+                continue;
+
             // when extracting dependencies, we want to extract
             // all members of the containing class, not just this one
             if(auto* TD = dyn_cast<TagDecl>(DC))
@@ -1519,6 +1524,16 @@ class ASTVisitor
                 return false;
         }
 
+        // don't extract anonymous unions
+        if(const auto* RD = dyn_cast<RecordDecl>(D);
+            RD && RD->isAnonymousStructOrUnion())
+            return false;
+
+        // don't extract implicitly generated declarations
+        // (except for IndirectFieldDecls)
+        if(D->isImplicit() && !isa<IndirectFieldDecl>(D))
+            return false;
+
         if (!config_->input.include.empty())
         {
             // Get filename
@@ -1959,10 +1974,15 @@ class ASTVisitor
         {
             switch(D->getKind())
             {
+            case Decl::CXXRecord:
+                // we treat anonymous unions as "transparent"
+                if(auto* RD = cast<CXXRecordDecl>(D);
+                    RD->isAnonymousStructOrUnion())
+                    break;
+                [[fallthrough]];
             case Decl::TranslationUnit:
             case Decl::Namespace:
             case Decl::Enum:
-            case Decl::CXXRecord:
             case Decl::ClassTemplateSpecialization:
             case Decl::ClassTemplatePartialSpecialization:
                 return D;
@@ -2373,6 +2393,8 @@ class ASTVisitor
 
         I.Type = buildTypeInfo(D->getType());
 
+        I.IsVariant = D->getParent()->isUnion();
+
         I.IsMutable = D->isMutable();
 
         if(const Expr* E = D->getInClassInitializer())
@@ -2793,6 +2815,17 @@ class ASTVisitor
     void
     traverse(FieldDecl*);
 
+    /** Traverse a member of an anonymous union.
+
+        This function is called by traverseDecl to traverse
+        a member of an anonymous union.
+
+        A IndirectFieldDecl inherits from ValueDecl.
+
+     */
+    void
+    traverse(IndirectFieldDecl*);
+
     /** Traverse a concept definition
 
         This function is called by traverseDecl to traverse a
@@ -3061,6 +3094,14 @@ traverse(FieldDecl* D)
     auto [I, created] = *exp;
     buildField(I, created, D);
 }
+
+void
+ASTVisitor::
+traverse(IndirectFieldDecl* D)
+{
+    traverse(D->getAnonField());
+}
+
 //------------------------------------------------
 // ConceptDecl
 
@@ -3348,9 +3389,8 @@ traverseDecl(
 {
     MRDOCS_ASSERT(D);
 
-    // Decl had a semantic error or is implicitly
-    // generated by the implementation
-    if(D->isInvalidDecl() || D->isImplicit())
+    // Decl had a semantic error
+    if(D->isInvalidDecl())
         return;
 
     SymbolFilter::FilterScope scope(symbolFilter_);

src/lib/Gen/xml/XMLWriter.cpp

@@ -566,6 +566,7 @@ writeField(
             {"id", "is-mutable"}
         });
 
+    writeAttr(I.IsVariant, "is-variant", tags_);
     writeAttr(I.IsMaybeUnused, "maybe-unused", tags_);
     writeAttr(I.IsDeprecated, "deprecated", tags_);
     writeAttr(I.HasNoUniqueAddress, "no-unique-address", tags_);

src/lib/Metadata/DomMetadata.cpp

@@ -851,6 +851,7 @@ DomInfo<T>::construct() const
             { "default",            dom::stringOrNull(I_.Default.Written) },
             { "isMaybeUnused",      I_.IsMaybeUnused },
             { "isDeprecated",       I_.IsDeprecated },
+            { "isVariant",          I_.IsVariant },
             { "isMutable",          I_.IsMutable },
             { "isBitfield",         I_.IsBitfield },
             { "hasNoUniqueAddress", I_.HasNoUniqueAddress }

src/lib/Metadata/Reduce.cpp

@@ -292,6 +292,7 @@ void merge(FieldInfo& I, FieldInfo&& Other)
     mergeExprInfo(I.BitfieldWidth,
         std::move(Other.BitfieldWidth));
 
+    I.IsVariant |= Other.IsVariant;
     I.IsMutable |= Other.IsMutable;
     I.IsMaybeUnused |= Other.IsMaybeUnused;
     I.IsDeprecated |= Other.IsDeprecated;

test-files/golden-tests/union.cpp

@@ -0,0 +1,16 @@
+union A
+{
+    int x;
+    bool y;
+};
+
+struct B
+{
+    union
+    {
+        int x;
+        bool y;
+    };
+
+    int z;
+};

test-files/golden-tests/union.xml

@@ -0,0 +1,36 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<mrdocs xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+       xsi:noNamespaceSchemaLocation="https://github.com/cppalliance/mrdocs/raw/develop/mrdocs.rnc">
+<namespace id="//////////////////////////8=">
+  <union name="A" id="rOga+mYntM7ytFb7bhJSklZ0r34=">
+    <file path="union.cpp" line="1" class="def"/>
+    <field name="x" id="Be23kXXQRAQHfKNTp2HOM2jouJo=">
+      <file path="union.cpp" line="3" class="def"/>
+      <attr id="is-variant"/>
+      <type name="int"/>
+    </field>
+    <field name="y" id="HqUCV+CnE+akUirdwlf8maZxw40=">
+      <file path="union.cpp" line="4" class="def"/>
+      <attr id="is-variant"/>
+      <type name="bool"/>
+    </field>
+  </union>
+  <struct name="B" id="3JsK1DO0O+wZhv+0meptQrbs3fY=">
+    <file path="union.cpp" line="7" class="def"/>
+    <field name="x" id="QtOrWpj/+5ytPBCEoNlbW+uW/oA=">
+      <file path="union.cpp" line="11" class="def"/>
+      <attr id="is-variant"/>
+      <type name="int"/>
+    </field>
+    <field name="y" id="8o+2/UVx4hIiDLQRYohp688sXmI=">
+      <file path="union.cpp" line="12" class="def"/>
+      <attr id="is-variant"/>
+      <type name="bool"/>
+    </field>
+    <field name="z" id="zTVqdWL2ShJziu85kaeOk2wfYFs=">
+      <file path="union.cpp" line="15" class="def"/>
+      <type name="int"/>
+    </field>
+  </struct>
+</namespace>
+</mrdocs>