From d73ef135ba029db59c0b5649e6117845d9e39600 Mon Sep 17 00:00:00 2001 From: Jordan Rose Date: Wed, 6 Jun 2012 17:25:21 +0000 Subject: [PATCH] Add pedantic warning -Wempty-translation-unit (C11 6.9p1). In standard C since C89, a 'translation-unit' is syntactically defined to have at least one "external-declaration", which is either a decl or a function definition. In Clang the latter gives us a declaration as well. The tricky bit about this warning is that our predefines can contain external declarations (__builtin_va_list and the 128-bit integer types). Therefore our AST parser now makes sure we have at least one declaration that doesn't come from the predefines buffer. Also, remove bogus warning about empty source files. This doesn't catch source files that only contain comments, and never fired anyway because of our predefines. PR12665 and git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@158085 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/clang/Basic/DiagnosticParseKinds.td | 4 +- include/clang/Basic/SourceManager.h | 20 ++++++++ include/clang/Parse/Parser.h | 3 ++ lib/Basic/SourceManager.cpp | 1 + lib/Lex/Preprocessor.cpp | 2 +- lib/Parse/ParseAST.cpp | 54 +++++++++++++++------ lib/Parse/Parser.cpp | 4 -- test/Misc/warning-flags.c | 3 +- test/PCH/empty-with-headers.c | 27 +++++++++++ test/Parser/completely-empty-header-file.h | 0 test/Parser/empty-translation-unit.c | 10 ++++ test/Parser/opencl-pragma.cl | 2 +- test/Preprocessor/undef-error.c | 2 +- test/Sema/c89-2.c | 2 +- 14 files changed, 108 insertions(+), 26 deletions(-) create mode 100644 test/PCH/empty-with-headers.c create mode 100644 test/Parser/completely-empty-header-file.h create mode 100644 test/Parser/empty-translation-unit.c diff --git a/include/clang/Basic/DiagnosticParseKinds.td b/include/clang/Basic/DiagnosticParseKinds.td index a5057c9d32..9811bab293 100644 --- a/include/clang/Basic/DiagnosticParseKinds.td +++ b/include/clang/Basic/DiagnosticParseKinds.td @@ -20,7 +20,9 @@ def warn_file_asm_volatile : Warning< let CategoryName = "Parse Issue" in { -def ext_empty_source_file : Extension<"ISO C forbids an empty source file">; +def ext_empty_translation_unit : Extension< + "ISO C requires a translation unit to contain at least one declaration.">, + InGroup>; def warn_cxx98_compat_top_level_semi : Warning< "extra ';' outside of a function is incompatible with C++98">, InGroup, DefaultIgnore; diff --git a/include/clang/Basic/SourceManager.h b/include/clang/Basic/SourceManager.h index 3164f874f1..f7fb1f5231 100644 --- a/include/clang/Basic/SourceManager.h +++ b/include/clang/Basic/SourceManager.h @@ -584,6 +584,9 @@ class SourceManager : public RefCountedBase { /// \brief The file ID for the precompiled preamble there is one. FileID PreambleFileID; + /// \brief The file ID for the preprocessor's predefines. + FileID PredefinesFileID; + // Statistics for -print-stats. mutable unsigned NumLinearScans, NumBinaryProbes; @@ -628,6 +631,14 @@ public: MainFileID = createFileIDForMemBuffer(Buffer); return MainFileID; } + + /// \brief Create the FileID for a memory buffer that contains the + /// preprocessor's predefines. + FileID createPredefinesFileIDForMemBuffer(const llvm::MemoryBuffer *Buffer) { + assert(PredefinesFileID.isInvalid() && "PredefinesFileID already set!"); + PredefinesFileID = createFileIDForMemBuffer(Buffer); + return PredefinesFileID; + } //===--------------------------------------------------------------------===// // MainFileID creation and querying methods. @@ -636,6 +647,9 @@ public: /// getMainFileID - Returns the FileID of the main source file. FileID getMainFileID() const { return MainFileID; } + /// \brief Returns the FileID of the preprocessor predefines buffer. + FileID getPredefinesFileID() const { return PredefinesFileID; } + /// createMainFileID - Create the FileID for the main source file. FileID createMainFileID(const FileEntry *SourceFile, SrcMgr::CharacteristicKind Kind = SrcMgr::C_User) { @@ -1113,6 +1127,12 @@ public: return getFileID(Loc) == getMainFileID(); } + /// isFromPredefines - Returns true if the provided SourceLocation is + /// within the processor's predefines buffer. + bool isFromPredefines(SourceLocation Loc) const { + return getFileID(Loc) == getPredefinesFileID(); + } + /// isInSystemHeader - Returns if a SourceLocation is in a system header. bool isInSystemHeader(SourceLocation Loc) const { return getFileCharacteristic(Loc) != SrcMgr::C_User; diff --git a/include/clang/Parse/Parser.h b/include/clang/Parse/Parser.h index 07d6320901..2222e781e8 100644 --- a/include/clang/Parse/Parser.h +++ b/include/clang/Parse/Parser.h @@ -730,6 +730,9 @@ private: public: DiagnosticBuilder Diag(SourceLocation Loc, unsigned DiagID); DiagnosticBuilder Diag(const Token &Tok, unsigned DiagID); + DiagnosticBuilder Diag(unsigned DiagID) { + return Diag(Tok, DiagID); + } private: void SuggestParentheses(SourceLocation Loc, unsigned DK, diff --git a/lib/Basic/SourceManager.cpp b/lib/Basic/SourceManager.cpp index ed920eb488..783e073e66 100644 --- a/lib/Basic/SourceManager.cpp +++ b/lib/Basic/SourceManager.cpp @@ -407,6 +407,7 @@ SourceManager::~SourceManager() { void SourceManager::clearIDTables() { MainFileID = FileID(); + PredefinesFileID = FileID(); LocalSLocEntryTable.clear(); LoadedSLocEntryTable.clear(); SLocEntryLoaded.clear(); diff --git a/lib/Lex/Preprocessor.cpp b/lib/Lex/Preprocessor.cpp index d387f4392d..955c39cfe7 100644 --- a/lib/Lex/Preprocessor.cpp +++ b/lib/Lex/Preprocessor.cpp @@ -425,7 +425,7 @@ void Preprocessor::EnterMainSourceFile() { llvm::MemoryBuffer *SB = llvm::MemoryBuffer::getMemBufferCopy(Predefines, ""); assert(SB && "Cannot create predefined source buffer"); - FileID FID = SourceMgr.createFileIDForMemBuffer(SB); + FileID FID = SourceMgr.createPredefinesFileIDForMemBuffer(SB); assert(!FID.isInvalid() && "Could not create FileID for predefines?"); // Start parsing the predefines. diff --git a/lib/Parse/ParseAST.cpp b/lib/Parse/ParseAST.cpp index d1c2624f8c..3f86c4d2c8 100644 --- a/lib/Parse/ParseAST.cpp +++ b/lib/Parse/ParseAST.cpp @@ -12,6 +12,7 @@ //===----------------------------------------------------------------------===// #include "clang/Parse/ParseAST.h" +#include "clang/Parse/ParseDiagnostic.h" #include "clang/Sema/Sema.h" #include "clang/Sema/CodeCompleteConsumer.h" #include "clang/Sema/SemaConsumer.h" @@ -77,27 +78,50 @@ void clang::ParseAST(Sema &S, bool PrintStats, bool SkipFunctionBodies) { S.getPreprocessor().EnterMainSourceFile(); P.Initialize(); S.Initialize(); - - if (ExternalASTSource *External = S.getASTContext().getExternalSource()) + + // C11 6.9p1 says translation units must have at least one top-level + // declaration. C++ doesn't have this restriction. We also don't want to + // complain if we have a precompiled header, although technically if the PCH + // is empty we should still emit the (pedantic) diagnostic. + bool WarnForEmptyTU = !S.getLangOpts().CPlusPlus; + if (ExternalASTSource *External = S.getASTContext().getExternalSource()) { External->StartTranslationUnit(Consumer); - - bool Abort = false; + WarnForEmptyTU = false; + } + + // Clang's predefines contain top-level declarations for things like va_list, + // making it hard to tell if the /user's/ translation unit has at least one + // top-level declaration. So we parse cautiously, looking for a declaration + // that doesn't come from our predefines. + // Note that ParseTopLevelDecl returns 'true' at EOF. + SourceManager &SM = S.getSourceManager(); Parser::DeclGroupPtrTy ADecl; - - while (!P.ParseTopLevelDecl(ADecl)) { // Not end of file. - // If we got a null return and something *was* parsed, ignore it. This - // is due to a top-level semicolon, an action override, or a parse error - // skipping something. + while (WarnForEmptyTU && !P.ParseTopLevelDecl(ADecl)) { if (ADecl) { - if (!Consumer->HandleTopLevelDecl(ADecl.get())) { - Abort = true; - break; + if (!Consumer->HandleTopLevelDecl(ADecl.get())) + return; + if (DeclGroupRef::iterator FirstDecl = ADecl.get().begin()) { + SourceLocation DeclLoc = (*FirstDecl)->getLocation(); + WarnForEmptyTU = SM.isFromPredefines(DeclLoc); } } - }; + } - if (Abort) - return; + // If we ended up seeing EOF before any top-level declarations, emit our + // diagnostic. Otherwise, parse the rest of the file normally. + if (WarnForEmptyTU) { + P.Diag(diag::ext_empty_translation_unit); + } else { + while (!P.ParseTopLevelDecl(ADecl)) { // Not end of file. + // If we got a null return and something *was* parsed, ignore it. This + // is due to a top-level semicolon, an action override, or a parse error + // skipping something. + if (ADecl) { + if (!Consumer->HandleTopLevelDecl(ADecl.get())) + return; + } + }; + } // Process any TopLevelDecls generated by #pragma weak. for (SmallVector::iterator diff --git a/lib/Parse/Parser.cpp b/lib/Parse/Parser.cpp index 504071405b..f0e2b3aa85 100644 --- a/lib/Parse/Parser.cpp +++ b/lib/Parse/Parser.cpp @@ -439,10 +439,6 @@ void Parser::Initialize() { // Prime the lexer look-ahead. ConsumeToken(); - if (Tok.is(tok::eof) && - !getLangOpts().CPlusPlus) // Empty source file is an extension in C - Diag(Tok, diag::ext_empty_source_file); - // Initialization for Objective-C context sensitive keywords recognition. // Referenced in Parser::ParseObjCTypeQualifierList. if (getLangOpts().ObjC1) { diff --git a/test/Misc/warning-flags.c b/test/Misc/warning-flags.c index 98130c5e27..cdfb38fb41 100644 --- a/test/Misc/warning-flags.c +++ b/test/Misc/warning-flags.c @@ -17,7 +17,7 @@ This test serves two purposes: The list of warnings below should NEVER grow. It should gradually shrink to 0. -CHECK: Warnings without flags (242): +CHECK: Warnings without flags (241): CHECK-NEXT: ext_anonymous_struct_union_qualified CHECK-NEXT: ext_binary_literal CHECK-NEXT: ext_cast_fn_obj @@ -26,7 +26,6 @@ CHECK-NEXT: ext_designated_init CHECK-NEXT: ext_duplicate_declspec CHECK-NEXT: ext_ellipsis_exception_spec CHECK-NEXT: ext_empty_fnmacro_arg -CHECK-NEXT: ext_empty_source_file CHECK-NEXT: ext_enum_friend CHECK-NEXT: ext_enum_value_not_int CHECK-NEXT: ext_enumerator_list_comma diff --git a/test/PCH/empty-with-headers.c b/test/PCH/empty-with-headers.c new file mode 100644 index 0000000000..751be1c9eb --- /dev/null +++ b/test/PCH/empty-with-headers.c @@ -0,0 +1,27 @@ +// RUN: %clang_cc1 -fsyntax-only -std=c99 -pedantic-errors %s +// RUN: %clang_cc1 -fsyntax-only -std=c99 -emit-pch -o %t %s +// RUN: %clang_cc1 -fsyntax-only -std=c99 -pedantic-errors -include-pch %t %s + +// RUN: %clang_cc1 -fsyntax-only -std=c99 -pedantic-errors -DINCLUDED %s -verify +// This last one should warn for -Wempty-translation-unit (C99 6.9p1). + +#if defined(INCLUDED) + +// empty except for the prefix header + +#elif defined(HEADER) + +typedef int my_int; +#define INCLUDED + +#else + +#define HEADER +#include "empty-with-headers.c" +// empty except for the header + +#endif + +// This should only fire if the header is not included, +// either explicitly or as a prefix header. +// expected-error{{ISO C requires a translation unit to contain at least one declaration.}} diff --git a/test/Parser/completely-empty-header-file.h b/test/Parser/completely-empty-header-file.h new file mode 100644 index 0000000000..e69de29bb2 diff --git a/test/Parser/empty-translation-unit.c b/test/Parser/empty-translation-unit.c new file mode 100644 index 0000000000..0dbf37e447 --- /dev/null +++ b/test/Parser/empty-translation-unit.c @@ -0,0 +1,10 @@ +// RUN: %clang_cc1 -fsyntax-only -std=c99 -pedantic -W -verify %s +// RUN: %clang_cc1 -fsyntax-only -x c++ -std=c++03 -pedantic-errors -W %s + +#include "completely-empty-header-file.h" +// no-warning -- an empty file is OK + +#define A_MACRO_IS_NOT_GOOD_ENOUGH 1 + +// In C we should get this warning, but in C++ we shouldn't. +// expected-warning{{ISO C requires a translation unit to contain at least one declaration.}} diff --git a/test/Parser/opencl-pragma.cl b/test/Parser/opencl-pragma.cl index 1946077113..4c48b2a496 100644 --- a/test/Parser/opencl-pragma.cl +++ b/test/Parser/opencl-pragma.cl @@ -1,4 +1,4 @@ -// RUN: %clang_cc1 %s -verify -pedantic -fsyntax-only +// RUN: %clang_cc1 %s -verify -pedantic -Wno-empty-translation-unit -fsyntax-only #pragma OPENCL EXTENSION cl_khr_fp16 : enable diff --git a/test/Preprocessor/undef-error.c b/test/Preprocessor/undef-error.c index ad611deced..959c163e03 100644 --- a/test/Preprocessor/undef-error.c +++ b/test/Preprocessor/undef-error.c @@ -1,4 +1,4 @@ -// RUN: %clang_cc1 %s -pedantic-errors -verify +// RUN: %clang_cc1 %s -pedantic-errors -Wno-empty-translation-unit -verify // PR2045 #define b diff --git a/test/Sema/c89-2.c b/test/Sema/c89-2.c index f6f6bd9720..14b955a6a4 100644 --- a/test/Sema/c89-2.c +++ b/test/Sema/c89-2.c @@ -1,4 +1,4 @@ -/* RUN: %clang_cc1 %s -std=c89 -pedantic-errors -verify +/* RUN: %clang_cc1 %s -std=c89 -pedantic-errors -Wno-empty-translation-unit -verify */ #if 1LL /* expected-error {{long long}} */ -- 2.40.0