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feat(lint): libclang-backed token layer

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Adds LintContext::Tokens() and friends, backed by clang_tokenize, as the
substrate the rules will move onto. Nothing consumes it yet.

libclang is dlopen'd rather than linked: -lclang would break the mingw and
MSVC cross-builds at link time and would put a libclang.so.NN runtime
dependency into the otherwise self-contained release tarballs. The clang-c
header is used for its declarations only, and the function-pointer table is
typed with decltype so the signatures cannot drift from the real API.

Three properties this buys that the hand-rolled scanners could not have:

  - a raw string literal or block comment is ONE token, so the documented
    "raw string literals are not recognized" limitation goes away;
  - `//` inside a literal is not a comment, so LineHasComment() replaces the
    Line(n).contains("//") probes that false-positive on it;
  - tokens cover preprocessor branches that are inactive for the host, since
    clang_tokenize lexes rather than evaluates #if. Token rules therefore
    keep seeing every platform's code, which an AST could not offer.

The parse backing the tokenizer is expected to fail on module units — no
PCMs, no build flags — and that is fine, because lexing has no semantic
prerequisites. Verified in the new tests.

LintSummary::Clean() now counts `errors`. It previously ignored them, so an
infrastructure failure that produced no findings reported clean and exited
0; a missing libclang would have been exactly that.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
This commit is contained in:
Jorijn van der Graaf 2026-07-27 02:54:38 +02:00
commit 5888af29ed
4 changed files with 387 additions and 2 deletions
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237
implementations/Crafter.Build-Lint.cpp
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@ -2,6 +2,12 @@
// SPDX-FileCopyrightText: Copyright (C) 2026 Catcrafts®
module;
#include <clang-c/Index.h>
#if defined(CRAFTER_BUILD_CONFIGURATION_TARGET_x86_64_pc_windows_msvc) || defined(CRAFTER_BUILD_CONFIGURATION_TARGET_x86_64_w64_mingw32)
#include <windows.h>
#else
#include <dlfcn.h>
#endif
export module Crafter.Build:Lint_impl;
import std;
import :Lint;
@ -12,6 +18,203 @@ namespace fs = std::filesystem;
using namespace Crafter;
namespace {
// ---------------- libclang ----------------
//
// libclang is loaded at runtime rather than linked. Linking -lclang would
// break the mingw and MSVC cross-builds at link time and would put a
// libclang.so.NN runtime dependency into the otherwise self-contained
// release tarballs; the clang-c header is used for its declarations only,
// and every call goes through a pointer resolved here. Failure to load is
// a hard error surfaced once by RunLint — there is deliberately no second,
// weaker lexer to fall back to, because two engines disagreeing about what
// is a comment is a worse failure than not running.
#if defined(CRAFTER_BUILD_CONFIGURATION_TARGET_x86_64_pc_windows_msvc) || defined(CRAFTER_BUILD_CONFIGURATION_TARGET_x86_64_w64_mingw32)
using LibHandle = HMODULE;
LibHandle OpenLibrary(const std::string& name) { return LoadLibraryA(name.c_str()); }
void* LibrarySymbol(LibHandle handle, const std::string& name) { return reinterpret_cast<void*>(GetProcAddress(handle, name.c_str())); }
constexpr std::string_view LibClangNames[] = {"libclang.dll", "clang.dll"};
#else
using LibHandle = void*;
LibHandle OpenLibrary(const std::string& name) { return dlopen(name.c_str(), RTLD_NOW | RTLD_LOCAL); }
void* LibrarySymbol(LibHandle handle, const std::string& name) { return dlsym(handle, name.c_str()); }
constexpr std::string_view LibClangNames[] = {
"libclang.so", "libclang.so.22.1", "libclang.so.21.1", "libclang.so.20.1",
"libclang.so.1", "libclang.dylib",
};
#endif
// Signatures come from decltype on the header's declarations, so they can
// never drift from the real API. decltype is unevaluated, so naming the
// functions here does not create a link-time reference to them.
struct LibClang {
LibHandle handle = nullptr;
std::string error; // non-empty exactly when handle is null
decltype(&clang_createIndex) CreateIndex = nullptr;
decltype(&clang_disposeIndex) DisposeIndex = nullptr;
decltype(&clang_parseTranslationUnit) ParseTranslationUnit = nullptr;
decltype(&clang_disposeTranslationUnit) DisposeTranslationUnit = nullptr;
decltype(&clang_getFile) GetFile = nullptr;
decltype(&clang_getLocationForOffset) GetLocationForOffset = nullptr;
decltype(&clang_getRange) GetRange = nullptr;
decltype(&clang_getRangeStart) GetRangeStart = nullptr;
decltype(&clang_getRangeEnd) GetRangeEnd = nullptr;
decltype(&clang_getFileLocation) GetFileLocation = nullptr;
decltype(&clang_tokenize) Tokenize = nullptr;
decltype(&clang_disposeTokens) DisposeTokens = nullptr;
decltype(&clang_getTokenKind) GetTokenKind = nullptr;
decltype(&clang_getTokenExtent) GetTokenExtent = nullptr;
};
LibClang LoadLibClang() {
LibClang lib;
std::vector<std::string> tried;
// CRAFTER_BUILD_LIBCLANG pins an exact path, mirroring the LIBCXX_DIR /
// CRAFTER_MINGW_DIR overrides used elsewhere. It is exclusive: pointing
// it at a broken path must fail loudly rather than quietly succeed with
// some other libclang, or the override is useless for diagnosing which
// library is actually in play.
std::vector<std::string> candidates;
if (const char* pinned = std::getenv("CRAFTER_BUILD_LIBCLANG"); pinned && *pinned) {
candidates.emplace_back(pinned);
} else {
for (std::string_view name : LibClangNames) candidates.emplace_back(name);
}
auto join = [](const std::vector<std::string>& parts) {
std::string joined;
for (const std::string& part : parts) {
if (!joined.empty()) joined += ", ";
joined += part;
}
return joined;
};
for (const std::string& name : candidates) {
lib.handle = OpenLibrary(name);
if (lib.handle) break;
tried.push_back(name);
}
if (!lib.handle) {
lib.error = std::format("could not load libclang (tried {}); install clang, or point CRAFTER_BUILD_LIBCLANG at it", join(tried));
return lib;
}
std::vector<std::string> missing;
auto bind = [&](auto& slot, const std::string& name) {
slot = reinterpret_cast<std::remove_reference_t<decltype(slot)>>(LibrarySymbol(lib.handle, name));
if (!slot) missing.push_back(name);
};
bind(lib.CreateIndex, "clang_createIndex");
bind(lib.DisposeIndex, "clang_disposeIndex");
bind(lib.ParseTranslationUnit, "clang_parseTranslationUnit");
bind(lib.DisposeTranslationUnit, "clang_disposeTranslationUnit");
bind(lib.GetFile, "clang_getFile");
bind(lib.GetLocationForOffset, "clang_getLocationForOffset");
bind(lib.GetRange, "clang_getRange");
bind(lib.GetRangeStart, "clang_getRangeStart");
bind(lib.GetRangeEnd, "clang_getRangeEnd");
bind(lib.GetFileLocation, "clang_getFileLocation");
bind(lib.Tokenize, "clang_tokenize");
bind(lib.DisposeTokens, "clang_disposeTokens");
bind(lib.GetTokenKind, "clang_getTokenKind");
bind(lib.GetTokenExtent, "clang_getTokenExtent");
if (!missing.empty()) {
lib.handle = nullptr;
lib.error = std::format("loaded {} but it is missing {}", candidates.front(), join(missing));
}
return lib;
}
const LibClang& Clang() {
static const LibClang Lib = LoadLibClang();
return Lib;
}
// The -x language for a source file, or empty when we must not lex it.
// .cppm needs c++-module explicitly: libclang does not infer a module unit
// from the extension and silently treats every flag as a linker input if
// left to guess. Shaders and data files return empty — lexing GLSL as C++
// yields plausible-looking nonsense.
std::string_view LexLanguage(const fs::path& file) {
std::string ext = file.extension().string();
if (ext == ".cppm" || ext == ".ixx") return "c++-module";
if (ext == ".cpp" || ext == ".cc" || ext == ".cxx" || ext == ".h" || ext == ".hpp" || ext == ".cu") return "c++";
if (ext == ".c") return "c";
return {};
}
LintTokenKind MapTokenKind(CXTokenKind kind) {
switch (kind) {
case CXToken_Punctuation: return LintTokenKind::Punctuation;
case CXToken_Keyword: return LintTokenKind::Keyword;
case CXToken_Identifier: return LintTokenKind::Identifier;
case CXToken_Literal: return LintTokenKind::Literal;
case CXToken_Comment: return LintTokenKind::Comment;
}
return LintTokenKind::Punctuation;
}
// Lex `content` as if it were `file`, returning tokens in source order.
//
// The buffer is handed over as an unsaved file, so a transform's in-memory
// edits are what get lexed — never the stale bytes on disk. The parse is
// expected to fail (a module unit's `import std;` cannot resolve without
// PCMs, and we deliberately do not supply the build's flags here); that
// does not matter, because clang_tokenize re-lexes the buffer and lexing
// has no semantic prerequisites. SingleFileParse keeps it from chasing
// #includes it does not need.
std::vector<LintToken> LexFile(const fs::path& file, const std::string& content) {
std::string_view language = LexLanguage(file);
if (language.empty()) return {};
const LibClang& lc = Clang();
if (!lc.handle) return {};
std::string path = file.string();
std::string languageArg = std::format("-x{}", language);
std::string standardArg = language == "c" ? "-std=c23" : "-std=c++26";
// clang's argv is char* by contract; keep the raw pointers confined to
// this call rather than letting them into any signature of ours.
std::array<const char*, 4> args{languageArg.c_str(), standardArg.c_str(), "-ferror-limit=0", "-w"};
CXUnsavedFile unsaved{};
unsaved.Filename = path.c_str();
unsaved.Contents = content.data();
unsaved.Length = static_cast<std::uint32_t>(content.size());
CXIndex index = lc.CreateIndex(0, 0);
if (!index) return {};
CXTranslationUnit tu = lc.ParseTranslationUnit(index, path.c_str(), args.data(), static_cast<std::int32_t>(args.size()), &unsaved, 1, CXTranslationUnit_SingleFileParse | CXTranslationUnit_SkipFunctionBodies | CXTranslationUnit_KeepGoing);
if (!tu) {
lc.DisposeIndex(index);
return {};
}
std::vector<LintToken> tokens;
if (CXFile cxFile = lc.GetFile(tu, path.c_str())) {
CXSourceRange whole = lc.GetRange(lc.GetLocationForOffset(tu, cxFile, 0), lc.GetLocationForOffset(tu, cxFile, static_cast<std::uint32_t>(content.size())));
CXToken* raw = nullptr;
std::uint32_t count = 0;
lc.Tokenize(tu, whole, &raw, &count);
tokens.reserve(count);
for (std::uint32_t i = 0; i < count; ++i) {
CXSourceRange extent = lc.GetTokenExtent(tu, raw[i]);
std::uint32_t line = 0;
std::uint32_t column = 0;
std::uint32_t begin = 0;
std::uint32_t end = 0;
lc.GetFileLocation(lc.GetRangeStart(extent), nullptr, &line, &column, &begin);
lc.GetFileLocation(lc.GetRangeEnd(extent), nullptr, nullptr, nullptr, &end);
if (end < begin || begin > content.size()) continue;
tokens.push_back({MapTokenKind(lc.GetTokenKind(raw[i])), begin, std::min<std::size_t>(end - begin, content.size() - begin), line, column});
}
if (raw) lc.DisposeTokens(tu, raw, count);
}
lc.DisposeTranslationUnit(tu);
lc.DisposeIndex(index);
return tokens;
}
// Blank //-comments, /*...*/ comments and string/char literal bodies to
// spaces while copying '\n' through, so byte offsets and line numbers in
// the result match the original text. Raw string literals are not
@ -164,6 +367,30 @@ const std::string& LintContext::CommentStripped() {
return *commentStrippedCache;
}
std::span<const LintToken> LintContext::Tokens() {
if (!tokenCache) tokenCache = LexFile(file, content);
return *tokenCache;
}
std::string_view LintContext::TokenText(const LintToken& token) const {
if (token.offset >= content.size()) return {};
return std::string_view(content).substr(token.offset, token.length);
}
std::span<const LintToken> LintContext::TokensOnLine(std::size_t line) {
// Tokens come back in source order, so one line's tokens are a contiguous
// run and can be bracketed by binary search.
std::span<const LintToken> all = Tokens();
auto begin = std::ranges::lower_bound(all, line, {}, &LintToken::line);
auto end = std::ranges::upper_bound(all, line, {}, &LintToken::line);
return all.subspan(static_cast<std::size_t>(begin - all.begin()), static_cast<std::size_t>(end - begin));
}
bool LintContext::LineHasComment(std::size_t line) {
std::span<const LintToken> onLine = TokensOnLine(line);
return std::ranges::any_of(onLine, [](const LintToken& t) { return t.kind == LintTokenKind::Comment; });
}
void LintContext::Report(std::size_t line, std::string message) {
sink->push_back({file, line, activeRule, std::move(message)});
}
@ -226,6 +453,7 @@ void LintContext::SetContent(std::string newContent) {
lines = SplitLines(content);
commentStrippedCache.reset();
suppressionsCache.reset(); // line numbers may have shifted — re-parse
tokenCache.reset(); // offsets refer to the old buffer — re-lex
}
void Configuration::AddLintRule(std::string name, std::function<void(LintContext&)> check) {
@ -235,6 +463,15 @@ void Configuration::AddLintRule(std::string name, std::function<void(LintContext
LintSummary Crafter::RunLint(Configuration& projectCfg, const RunLintOptions& opts) {
LintSummary summary;
// libclang backs the lexer every rule reads through, so a failed load is
// fatal rather than a downgrade: running the rules without it would report
// against a substrate that disagrees with the one they were written for.
if (const LibClang& lc = Clang(); !lc.handle) {
std::println(std::cerr, "lint: {}", lc.error);
++summary.errors;
return summary;
}
fs::path projectRoot = opts.projectFile.empty()
? fs::absolute(projectCfg.path)
: opts.projectFile.parent_path();