feat(hover): show include paths and TagDecl members

docs/en/features/hover.md

@@ -237,7 +237,7 @@
 
 ## Special Hover Targets
 
-- [ ] Show struct/enum members on type-level hover ([clangd#959](https://github.com/clangd/clangd/issues/959))
+- [x] Show struct/enum members on type-level hover ([clangd#959](https://github.com/clangd/clangd/issues/959))
 
   ```cpp
   enum Color { Red, Green, Blue };
@@ -266,7 +266,7 @@
   // hover on "nodiscard" → description of the attribute
   ```
 
-- [ ] `#include` directive hover showing resolved header path
+- [x] `#include` directive hover showing resolved header path
 - [x] `this` expression hover showing pointed-to type
 - [x] `__func__` and related predefined identifier hover
 

docs/zh/features/hover.md

@@ -237,7 +237,7 @@
 
 ## 特殊悬停目标
 
-- [ ] 类型级悬停显示结构体/枚举成员（[clangd#959](https://github.com/clangd/clangd/issues/959)）
+- [x] 类型级悬停显示结构体/枚举成员（[clangd#959](https://github.com/clangd/clangd/issues/959)）
 
   ```cpp
   enum Color { Red, Green, Blue };
@@ -266,7 +266,7 @@
   // 悬停 "nodiscard" → 显示该属性的说明
   ```
 
-- [ ] `#include` 指令悬停显示解析后的头文件路径
+- [x] `#include` 指令悬停显示解析后的头文件路径
 - [x] `this` 表达式悬停显示指向的类型
 - [x] `__func__` 及相关预定义标识符悬停
 

src/feature/hover.cpp

@@ -10,6 +10,7 @@
 #include "semantic/ast_utility.h"
 #include "semantic/find_target.h"
 #include "semantic/selection.h"
+#include "syntax/lexer.h"
 
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringExtras.h"
@@ -117,6 +118,58 @@ auto namespace_scope(const clang::Decl* decl) -> std::string {
     return "";
 }
 
+void print_tag_name(std::string& definition,
+                    const clang::TagDecl& decl,
+                    clang::PrintingPolicy policy) {
+    /// We only need the full tag name, so truncate the body at the opening brace for later fill-in.
+    llvm::raw_string_ostream os(definition);
+    decl.print(os, policy);
+    auto body = definition.rfind('{');
+    if(body == std::string::npos) {
+        return;
+    }
+    definition.resize(body);
+}
+
+auto print_record_definition(const clang::RecordDecl& decl, clang::PrintingPolicy policy)
+    -> std::string {
+    std::string definition;
+
+    print_tag_name(definition, decl, policy);
+
+    llvm::raw_string_ostream os(definition);
+    os << " {";
+    for(const clang::FieldDecl* field: decl.fields()) {
+        os << '\n';
+        field->print(os, policy);
+        os << ';';
+    }
+    os << "\n}";
+
+    return definition;
+}
+
+auto print_enum_definition(const clang::EnumDecl& decl, clang::PrintingPolicy policy)
+    -> std::string {
+    std::string definition;
+
+    print_tag_name(definition, decl, policy);
+
+    llvm::raw_string_ostream os(definition);
+    os << " {";
+    for(const clang::EnumConstantDecl* enumerator: decl.enumerators()) {
+        os << '\n';
+        enumerator->print(os, policy);
+        if(!enumerator->getInitExpr() && !enumerator->getType()->isDependentType()) {
+            os << " = " << llvm::toString(enumerator->getInitVal(), 10);
+        }
+        os << ',';
+    }
+    os << "\n}";
+
+    return definition;
+}
+
 auto print_definition(const clang::Decl* decl,
                       clang::PrintingPolicy policy,
                       const clang::syntax::TokenBuffer& tb) -> std::string {
@@ -129,6 +182,14 @@ auto print_definition(const clang::Decl* decl,
                 policy.SuppressInitializers = true;
             }
         }
+    } else if(auto* record = llvm::dyn_cast<clang::RecordDecl>(decl)) {
+        if(auto* definition = record->getDefinition()) {
+            return print_record_definition(*definition, policy);
+        }
+    } else if(auto* enum_decl = llvm::dyn_cast<clang::EnumDecl>(decl)) {
+        if(auto* definition = enum_decl->getDefinition()) {
+            return print_enum_definition(*definition, policy);
+        }
     }
 
     std::string definition;
@@ -1044,6 +1105,57 @@ auto attr_hover(const clang::Attr* attr, clang::ASTContext& context) -> std::opt
     return info;
 }
 
+auto include_hover(CompilationUnitRef unit, std::uint32_t offset) -> std::optional<HoverInfo> {
+    auto interested = unit.interested_file();
+    auto directives_it = unit.directives().find(interested);
+    if(directives_it == unit.directives().end()) {
+        return std::nullopt;
+    }
+
+    auto content = unit.interested_content();
+    auto* lang_opts = &unit.lang_options();
+
+    auto header_name = [&](LocalSourceRange range) -> std::string {
+        auto arg = content.substr(range.begin, range.end - range.begin).trim();
+        if(arg.size() >= 2 && ((arg.front() == '"' && arg.back() == '"') ||
+                               (arg.front() == '<' && arg.back() == '>'))) {
+            arg = arg.drop_front().drop_back();
+        }
+        return arg.str();
+    };
+
+    auto try_directive = [&](clang::SourceLocation loc,
+                             clang::FileID target) -> std::optional<HoverInfo> {
+        if(!target.isValid())
+            return std::nullopt;
+        auto [fid, directive_offset] = unit.decompose_location(loc);
+        if(fid != interested || directive_offset >= content.size())
+            return std::nullopt;
+        auto range = find_directive_argument(content, directive_offset, lang_opts);
+        if(!range || !range->contains(offset))
+            return std::nullopt;
+
+        HoverInfo info;
+        info.name = header_name(*range);
+        info.kind = SymbolKind::Header;
+        info.definition = unit.file_path(target);
+        info.symbol_range = *range;
+        return info;
+    };
+
+    for(const auto& include: directives_it->second.includes) {
+        if(auto info = try_directive(include.location, include.fid)) {
+            return info;
+        }
+    }
+    for(const auto& has_include: directives_it->second.has_includes) {
+        if(auto info = try_directive(has_include.location, has_include.fid)) {
+            return info;
+        }
+    }
+    return std::nullopt;
+}
+
 void add_layout_info(const clang::NamedDecl& decl, HoverInfo& info) {
     if(decl.isInvalidDecl()) {
         return;
@@ -1504,6 +1616,11 @@ llvm::raw_ostream& operator<<(llvm::raw_ostream& os, const HoverInfo::Param& par
 
 auto hover_info(CompilationUnitRef unit, std::uint32_t offset, const HoverOptions& options)
     -> std::optional<HoverInfo> {
+    /// The hover is over an include directive.
+    if(auto info = include_hover(unit, offset)) {
+        return info;
+    }
+
     auto& context = unit.context();
     auto policy = hover_printing_policy(context.getPrintingPolicy());
 

tests/data/hover/tag_decls.cpp

@@ -152,3 +152,79 @@ namespace nested_templates_class {
 template <class T> struct cls {};
 $(17_nested_template_class)cls<cls<cls<int>>> foo;
 }
+
+namespace enum_explicit {
+enum Color {
+  RED = -123,
+  GREEN,
+  BLUE = 5,
+};
+void foo() {
+  $(18_enum_explicit)Color color = GREEN;
+}
+}
+
+namespace struct_fields {
+struct Point {
+  int x;
+  int y;
+};
+void foo() {
+  $(19_struct_fields)Point point;
+}
+}
+
+namespace inherited_struct {
+struct base {
+  int a;
+};
+
+struct Point : base {
+  int x;
+  int y;
+};
+void foo() {
+  $(20_inherited_struct)Point point;
+}
+}
+
+namespace inherited_class {
+struct first {};
+struct second {};
+
+class Point : public first, virtual protected second {
+  int value;
+};
+void foo() {
+  $(21_inherited_class)Point point;
+}
+}
+
+namespace template_fields {
+template <typename T>
+struct Box {
+  T value;
+};
+void foo() {
+  $(22_template_fields)Box<int> box;
+}
+}
+
+namespace inline_method_body {
+struct Widget {
+  int value;
+  int get() const { return value; }
+};
+void foo() {
+  $(23_inline_method_body)Widget widget;
+}
+}
+
+namespace lambda_field_body {
+struct Widget {
+  int value = [] { return 42; }();
+};
+void foo() {
+  $(24_lambda_field_body)Widget widget;
+}
+}