feat: add SearchConfig, ToolchainProvider, PathPool and related tests (#370)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

src/command/search_config.cpp

@@ -0,0 +1,134 @@
+#include "command/search_config.h"
+
+#include "command/driver.h"
+
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/StringSet.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/Path.h"
+
+namespace clice {
+
+using ID = clang::driver::options::ID;
+
+SearchConfig extract_search_config(llvm::ArrayRef<const char*> arguments,
+                                   llvm::StringRef directory) {
+    // Replicate clang's InitHeaderSearch::Realize layout:
+    //   Quoted (-iquote) → Angled (-I) → System (-isystem, -internal-isystem, etc.)
+    // Then deduplicate across [Angled..end) matching clang's RemoveDuplicates.
+
+    std::vector<SearchDir> quoted;
+    std::vector<SearchDir> angled;
+    std::vector<SearchDir> system;
+    std::vector<SearchDir> after;
+
+    auto make_absolute = [&](llvm::StringRef path) -> std::string {
+        llvm::SmallString<256> abs_path(path);
+        if(!llvm::sys::path::is_absolute(abs_path)) {
+            llvm::sys::fs::make_absolute(directory, abs_path);
+        }
+        llvm::sys::path::remove_dots(abs_path, true);
+        return abs_path.str().str();
+    };
+
+    // Track -iprefix state for -iwithprefix/-iwithprefixbefore.
+    std::string prefix;
+
+    llvm::BumpPtrAllocator allocator;
+    ArgumentParser parser{&allocator};
+
+    parser.parse(
+        llvm::ArrayRef(arguments).drop_front(),
+        [&](std::unique_ptr<llvm::opt::Arg> arg) {
+            auto id = arg->getOption().getID();
+            switch(id) {
+                // Quoted group (clang: frontend::Quoted)
+                case ID::OPT_iquote: quoted.push_back({make_absolute(arg->getValue())}); break;
+
+                // Angled group (clang: frontend::Angled)
+                case ID::OPT_I: angled.push_back({make_absolute(arg->getValue())}); break;
+
+                // System group (clang: frontend::System / ExternCSystem)
+                case ID::OPT_isystem:
+                case ID::OPT_internal_isystem:
+                case ID::OPT_internal_externc_isystem:
+                    system.push_back({make_absolute(arg->getValue())});
+                    break;
+
+                // Prefix options: must be processed in argument order.
+                case ID::OPT_iprefix: prefix = arg->getValue(); break;
+                case ID::OPT_iwithprefix:
+                    // clang maps to After group.
+                    after.push_back({make_absolute(prefix + arg->getValue())});
+                    break;
+                case ID::OPT_iwithprefixbefore:
+                    // clang maps to Angled group.
+                    angled.push_back({make_absolute(prefix + arg->getValue())});
+                    break;
+
+                case ID::OPT_idirafter: after.push_back({make_absolute(arg->getValue())}); break;
+
+                // TODO: -cxx-isystem (clang: frontend::CXXSystem, C++-only system dirs)
+                // TODO: -iwithsysroot (prepends sysroot to path, then adds to System)
+                // TODO: HeaderMap support (-I foo.hmap remaps include names)
+                default: break;
+            }
+        },
+        [](int, int) {});
+
+    // Concatenate: Quoted → Angled → System → After
+    SearchConfig config;
+    config.dirs.reserve(quoted.size() + angled.size() + system.size() + after.size());
+    config.dirs.insert(config.dirs.end(),
+                       std::make_move_iterator(quoted.begin()),
+                       std::make_move_iterator(quoted.end()));
+    config.angled_start_idx = static_cast<unsigned>(config.dirs.size());
+    config.dirs.insert(config.dirs.end(),
+                       std::make_move_iterator(angled.begin()),
+                       std::make_move_iterator(angled.end()));
+    config.system_start_idx = static_cast<unsigned>(config.dirs.size());
+    config.dirs.insert(config.dirs.end(),
+                       std::make_move_iterator(system.begin()),
+                       std::make_move_iterator(system.end()));
+    config.after_start_idx = static_cast<unsigned>(config.dirs.size());
+    config.dirs.insert(config.dirs.end(),
+                       std::make_move_iterator(after.begin()),
+                       std::make_move_iterator(after.end()));
+
+    // Deduplicate across [angled_start_idx..end), matching clang's
+    // RemoveDuplicates(SearchList, NumQuoted). If a path appears in both
+    // Angled and System, keep the first (Angled) occurrence. This is
+    // critical for #include_next correctness.
+    {
+        llvm::StringSet<> seen;
+        // Do NOT seed with Quoted paths. clang's RemoveDuplicates(SearchList,
+        // NumQuoted) starts from NumQuoted, so a path in both Quoted and Angled
+        // is kept in both — this matters for #include <...> and #include_next.
+
+        unsigned write = config.angled_start_idx;
+        unsigned removed_before_system = 0;
+        unsigned removed_before_after = 0;
+        for(unsigned read = config.angled_start_idx; read < config.dirs.size(); ++read) {
+            if(seen.insert(config.dirs[read].path).second) {
+                if(write != read) {
+                    config.dirs[write] = std::move(config.dirs[read]);
+                }
+                ++write;
+            } else {
+                if(read < config.system_start_idx) {
+                    ++removed_before_system;
+                }
+                if(read < config.after_start_idx) {
+                    ++removed_before_after;
+                }
+            }
+        }
+        config.dirs.resize(write);
+        config.system_start_idx -= removed_before_system;
+        config.after_start_idx -= removed_before_after;
+    }
+
+    return config;
+}
+
+}  // namespace clice