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+//===--- NoTrivialPPDirectiveTracer.h ---------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the NoTrivialPPDirectiveTracer interface.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_LEX_NO_TRIVIAL_PPDIRECTIVE_TRACER_H
+#define LLVM_CLANG_LEX_NO_TRIVIAL_PPDIRECTIVE_TRACER_H
+
+#include "clang/Lex/PPCallbacks.h"
+
+namespace clang {
+class Preprocessor;
+
+/// Consider the following code:
+///
+/// # 1 __FILE__ 1 3
+/// export module a;
+///
+/// According to the wording in
+/// [P1857R3](https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p1857r3.html):
+///
+/// A module directive may only appear as the first preprocessing tokens in a
+/// file (excluding the global module fragment.)
+///
+/// and the wording in
+/// [[cpp.pre]](https://eel.is/c++draft/cpp.pre#nt:module-file):
+/// module-file:
+/// pp-global-module-fragment[opt] pp-module group[opt]
+/// pp-private-module-fragment[opt]
+///
+/// `#` is the first pp-token in the translation unit, and it was rejected by
+/// clang, but they really should be exempted from this rule. The goal is to not
+/// allow any preprocessor conditionals or most state changes, but these don't
+/// fit that.
+///
+/// State change would mean most semantically observable preprocessor state,
+/// particularly anything that is order dependent. Global flags like being a
+/// system header/module shouldn't matter.
+///
+/// We should exempt a brunch of directives, even though it violates the current
+/// standard wording.
+///
+/// This class used to trace 'no-trivial' pp-directives in main file, which may
+/// change the preprocessing state.
+///
+/// FIXME: Once the wording of the standard is revised, we need to follow the
+/// wording of the standard. Currently this is just a workaround
+class NoTrivialPPDirectiveTracer : public PPCallbacks {
+ Preprocessor &PP;
+
+ /// Whether preprocessing main file. We only focus on the main file.
+ bool InMainFile = true;
+
+ /// Whether one or more conditional, include or other 'no-trivial'
+ /// pp-directives has seen before.
+ bool SeenNoTrivialPPDirective = false;
+
+ void setSeenNoTrivialPPDirective();
+
+public:
+ NoTrivialPPDirectiveTracer(Preprocessor &P) : PP(P) {}
+
+ bool hasSeenNoTrivialPPDirective() const;
+
+ /// Callback invoked whenever the \p Lexer moves to a different file for
+ /// lexing. Unlike \p FileChanged line number directives and other related
+ /// pragmas do not trigger callbacks to \p LexedFileChanged.
+ ///
+ /// \param FID The \p FileID that the \p Lexer moved to.
+ ///
+ /// \param Reason Whether the \p Lexer entered a new file or exited one.
+ ///
+ /// \param FileType The \p CharacteristicKind of the file the \p Lexer moved
+ /// to.
+ ///
+ /// \param PrevFID The \p FileID the \p Lexer was using before the change.
+ ///
+ /// \param Loc The location where the \p Lexer entered a new file from or the
+ /// location that the \p Lexer moved into after exiting a file.
+ void LexedFileChanged(FileID FID, LexedFileChangeReason Reason,
+ SrcMgr::CharacteristicKind FileType, FileID PrevFID,
+ SourceLocation Loc) override;
+
+ /// Callback invoked whenever an embed directive has been processed,
+ /// regardless of whether the embed will actually find a file.
+ ///
+ /// \param HashLoc The location of the '#' that starts the embed directive.
+ ///
+ /// \param FileName The name of the file being included, as written in the
+ /// source code.
+ ///
+ /// \param IsAngled Whether the file name was enclosed in angle brackets;
+ /// otherwise, it was enclosed in quotes.
+ ///
+ /// \param File The actual file that may be included by this embed directive.
+ ///
+ /// \param Params The parameters used by the directive.
+ void EmbedDirective(SourceLocation HashLoc, StringRef FileName, bool IsAngled,
+ OptionalFileEntryRef File,
+ const LexEmbedParametersResult &Params) override {
+ setSeenNoTrivialPPDirective();
+ }
+
+ /// Callback invoked whenever an inclusion directive of
+ /// any kind (\c \#include, \c \#import, etc.) has been processed, regardless
+ /// of whether the inclusion will actually result in an inclusion.
+ ///
+ /// \param HashLoc The location of the '#' that starts the inclusion
+ /// directive.
+ ///
+ /// \param IncludeTok The token that indicates the kind of inclusion
+ /// directive, e.g., 'include' or 'import'.
+ ///
+ /// \param FileName The name of the file being included, as written in the
+ /// source code.
+ ///
+ /// \param IsAngled Whether the file name was enclosed in angle brackets;
+ /// otherwise, it was enclosed in quotes.
+ ///
+ /// \param FilenameRange The character range of the quotes or angle brackets
+ /// for the written file name.
+ ///
+ /// \param File The actual file that may be included by this inclusion
+ /// directive.
+ ///
+ /// \param SearchPath Contains the search path which was used to find the file
+ /// in the file system. If the file was found via an absolute include path,
+ /// SearchPath will be empty. For framework includes, the SearchPath and
+ /// RelativePath will be split up. For example, if an include of "Some/Some.h"
+ /// is found via the framework path
+ /// "path/to/Frameworks/Some.framework/Headers/Some.h", SearchPath will be
+ /// "path/to/Frameworks/Some.framework/Headers" and RelativePath will be
+ /// "Some.h".
+ ///
+ /// \param RelativePath The path relative to SearchPath, at which the include
+ /// file was found. This is equal to FileName except for framework includes.
+ ///
+ /// \param SuggestedModule The module suggested for this header, if any.
+ ///
+ /// \param ModuleImported Whether this include was translated into import of
+ /// \p SuggestedModule.
+ ///
+ /// \param FileType The characteristic kind, indicates whether a file or
+ /// directory holds normal user code, system code, or system code which is
+ /// implicitly 'extern "C"' in C++ mode.
+ ///
+ void InclusionDirective(SourceLocation HashLoc, const Token &IncludeTok,
+ StringRef FileName, bool IsAngled,
+ CharSourceRange FilenameRange,
+ OptionalFileEntryRef File, StringRef SearchPath,
+ StringRef RelativePath, const Module *SuggestedModule,
+ bool ModuleImported,
+ SrcMgr::CharacteristicKind FileType) override {
+ setSeenNoTrivialPPDirective();
+ }
+
+ /// Callback invoked whenever there was an explicit module-import
+ /// syntax.
+ ///
+ /// \param ImportLoc The location of import directive token.
+ ///
+ /// \param Path The identifiers (and their locations) of the module
+ /// "path", e.g., "std.vector" would be split into "std" and "vector".
+ ///
+ /// \param Imported The imported module; can be null if importing failed.
+ ///
+ void moduleImport(SourceLocation ImportLoc, ModuleIdPath Path,
+ const Module *Imported) override {
+ setSeenNoTrivialPPDirective();
+ }
+
+ /// Callback invoked when the end of the main file is reached.
+ ///
+ /// No subsequent callbacks will be made.
+ void EndOfMainFile() override { setSeenNoTrivialPPDirective(); }
+
+ /// Callback invoked when start reading any pragma directive.
+ void PragmaDirective(SourceLocation Loc,
+ PragmaIntroducerKind Introducer) override {}
+
+ /// Called by Preprocessor::HandleMacroExpandedIdentifier when a
+ /// macro invocation is found.
+ void MacroExpands(const Token &MacroNameTok, const MacroDefinition &MD,
+ SourceRange Range, const MacroArgs *Args) override;
+
+ /// Hook called whenever a macro definition is seen.
+ void MacroDefined(const Token &MacroNameTok,
+ const MacroDirective *MD) override {
+ setSeenNoTrivialPPDirective();
+ }
+
+ /// Hook called whenever a macro \#undef is seen.
+ /// \param MacroNameTok The active Token
+ /// \param MD A MacroDefinition for the named macro.
+ /// \param Undef New MacroDirective if the macro was defined, null otherwise.
+ ///
+ /// MD is released immediately following this callback.
+ void MacroUndefined(const Token &MacroNameTok, const MacroDefinition &MD,
+ const MacroDirective *Undef) override {
+ setSeenNoTrivialPPDirective();
+ }
+
+ /// Hook called whenever the 'defined' operator is seen.
+ /// \param MD The MacroDirective if the name was a macro, null otherwise.
+ void Defined(const Token &MacroNameTok, const MacroDefinition &MD,
+ SourceRange Range) override {
+ setSeenNoTrivialPPDirective();
+ }
+
+ /// Hook called whenever an \#if is seen.
+ /// \param Loc the source location of the directive.
+ /// \param ConditionRange The SourceRange of the expression being tested.
+ /// \param ConditionValue The evaluated value of the condition.
+ ///
+ // FIXME: better to pass in a list (or tree!) of Tokens.
+ void If(SourceLocation Loc, SourceRange ConditionRange,
+ ConditionValueKind ConditionValue) override {
+ setSeenNoTrivialPPDirective();
+ }
+
+ /// Hook called whenever an \#elif is seen.
+ /// \param Loc the source location of the directive.
+ /// \param ConditionRange The SourceRange of the expression being tested.
+ /// \param ConditionValue The evaluated value of the condition.
+ /// \param IfLoc the source location of the \#if/\#ifdef/\#ifndef directive.
+ // FIXME: better to pass in a list (or tree!) of Tokens.
+ void Elif(SourceLocation Loc, SourceRange ConditionRange,
+ ConditionValueKind ConditionValue, SourceLocation IfLoc) override {
+ setSeenNoTrivialPPDirective();
+ }
+
+ /// Hook called whenever an \#ifdef is seen.
+ /// \param Loc the source location of the directive.
+ /// \param MacroNameTok Information on the token being tested.
+ /// \param MD The MacroDefinition if the name was a macro, null otherwise.
+ void Ifdef(SourceLocation Loc, const Token &MacroNameTok,
+ const MacroDefinition &MD) override {
+ setSeenNoTrivialPPDirective();
+ }
+
+ /// Hook called whenever an \#elifdef branch is taken.
+ /// \param Loc the source location of the directive.
+ /// \param MacroNameTok Information on the token being tested.
+ /// \param MD The MacroDefinition if the name was a macro, null otherwise.
+ void Elifdef(SourceLocation Loc, const Token &MacroNameTok,
+ const MacroDefinition &MD) override {
+ setSeenNoTrivialPPDirective();
+ }
+ /// Hook called whenever an \#elifdef is skipped.
+ /// \param Loc the source location of the directive.
+ /// \param ConditionRange The SourceRange of the expression being tested.
+ /// \param IfLoc the source location of the \#if/\#ifdef/\#ifndef directive.
+ // FIXME: better to pass in a list (or tree!) of Tokens.
+ void Elifdef(SourceLocation Loc, SourceRange ConditionRange,
+ SourceLocation IfLoc) override {
+ setSeenNoTrivialPPDirective();
+ }
+
+ /// Hook called whenever an \#ifndef is seen.
+ /// \param Loc the source location of the directive.
+ /// \param MacroNameTok Information on the token being tested.
+ /// \param MD The MacroDefiniton if the name was a macro, null otherwise.
+ void Ifndef(SourceLocation Loc, const Token &MacroNameTok,
+ const MacroDefinition &MD) override {
+ setSeenNoTrivialPPDirective();
+ }
+
+ /// Hook called whenever an \#elifndef branch is taken.
+ /// \param Loc the source location of the directive.
+ /// \param MacroNameTok Information on the token being tested.
+ /// \param MD The MacroDefinition if the name was a macro, null otherwise.
+ void Elifndef(SourceLocation Loc, const Token &MacroNameTok,
+ const MacroDefinition &MD) override {
+ setSeenNoTrivialPPDirective();
+ }
+ /// Hook called whenever an \#elifndef is skipped.
+ /// \param Loc the source location of the directive.
+ /// \param ConditionRange The SourceRange of the expression being tested.
+ /// \param IfLoc the source location of the \#if/\#ifdef/\#ifndef directive.
+ // FIXME: better to pass in a list (or tree!) of Tokens.
+ void Elifndef(SourceLocation Loc, SourceRange ConditionRange,
+ SourceLocation IfLoc) override {
+ setSeenNoTrivialPPDirective();
+ }
+
+ /// Hook called whenever an \#else is seen.
+ /// \param Loc the source location of the directive.
+ /// \param IfLoc the source location of the \#if/\#ifdef/\#ifndef directive.
+ void Else(SourceLocation Loc, SourceLocation IfLoc) override {
+ setSeenNoTrivialPPDirective();
+ }
+
+ /// Hook called whenever an \#endif is seen.
+ /// \param Loc the source location of the directive.
+ /// \param IfLoc the source location of the \#if/\#ifdef/\#ifndef directive.
+ void Endif(SourceLocation Loc, SourceLocation IfLoc) override {
+ setSeenNoTrivialPPDirective();
+ }
+};
+
+} // namespace clang
+
+#endif // LLVM_CLANG_LEX_NO_TRIVIAL_PPDIRECTIVE_TRACER_H