On Wed, 5 Dec 2018 at 11:14, Alex L via cfe-commits < cfe-commits@lists.llvm.org> wrote:
> We have about 100k unique occurrences of this warning across a slice of > our software stack. It's simply not feasible to us to adopt it, so we would > prefer for it to be reverted to avoid downstream divergence in Apple's > clang. Granted, these occur in projects that use -Weverything but those > projects are typically understanding of warnings that they can turn off > when they see that they provide useful value in terms of warnings about > unintended behavior that's sometimes caught. This warning doesn't seem to > catch unintended bugs and it would be a heroic battle to adopt it for us in > a way where projects are somewhat satisfied. It seems to be a better fit > for a clang-tidy check that could suggest automatic fixits and that the > users could run on their codebase to "modernize" if they want to. > Please refer to the review thread where -Weverything was added: http://lists.llvm.org/pipermail/cfe-commits/Week-of-Mon-20110815/045292.html Users using -Weverything have always been expected to turn off warnings that they find not useful for their use cases (or to not use -Weverything if they cannot tolerate new warnings) -- in fact, the very model for -Weverything is that you see new warnings and turn off the ones you don't like. That's the model that users explicitly opt into when they ask for -Weveryhing. It would be harmful to allow only lowest-common-denominator warnings in order to avoid breaking people who incautiously opted into -Weverything -Werror, so the fact that a disabled-by-default warning is problematic for such users is not a compelling reason to remove the warning. If the warning itself does not objectively have merit, then we can remove it, but the fact that it breaks -Weverything -Werror builds shouldn't be a consideration. Cheers, > Alex > > On Wed, 5 Dec 2018 at 10:43, Richard Smith via cfe-dev < > cfe-...@lists.llvm.org> wrote: > >> On Wed, 5 Dec 2018, 10:01 George Karpenkov via cfe-commits < >> cfe-commits@lists.llvm.org wrote: >> >>> These are the cases I get: >>> >>> #define unexpected(a) { kprintf("unexpected %s:%d\n", __FILE__, >>> __LINE__); a; } >>> >>> and >>> >>> #if 0 >>> #define DEBG(fmt, args...) { IOLog(fmt, ## args); kprintf(fmt, ## >>> args); } >>> #else >>> #define DEBG(fmt, args...) {} >>> #endif >>> >>> Now calls >>> >>> `DEBG(‘x’);` and `unexpected(‘msg’);` >>> >>> cause the warning to be fired. >>> Of course, semicolon could be omitted, but the fact that the macro has >>> braces is sort of an implementation detail. >>> >>> Greg Parker has pointed out it’s possible to rewrite the macros using >>> the “do { … } while (0)”, >>> but that is a lot of macros to change, and the resulting code would be >>> arguably less readable. >>> >> >> That suggestion is the (or at least an) idiomatic way to write a >> "statement-like" macro that expects a semicolon. The approach taken by the >> above macros is often considered to be a macro antipattern (try putting it >> in an unbraced if and adding an else clause, for example). >> >>> On Dec 5, 2018, at 5:10 AM, Aaron Ballman <aa...@aaronballman.com> >>> wrote: >>> >>> On Wed, Dec 5, 2018 at 1:40 AM Roman Lebedev <lebedev...@gmail.com> >>> wrote: >>> >>> >>> It is a problem in practice for us since we have projects which enable >>> all available warnings and also enable “-Werror”. >>> >>> Hm, they have asked for -Weverything and they got it. Seems to be >>> working as intended. >>> When in previous discussions elsewhere i have talked about >>> -Weverything, i was always >>> been told that it isn't supposed to be used like that (admittedly, i >>> *do* use it like that :)). >>> >>> Could you explain how is this different from any other warning that is >>> considered pointless by the project? >>> Why not simply disable it? >>> >>> >>> You are right, it could be disabled. It’s just for this warning the >>> noise vs. usefulness ratio seemed pretty low. >>> >>> >>> Would you be okay with the warning if it was only diagnosed when the >>> source location of the semi-colon is not immediately preceded by a >>> macro expansion location? e.g., >>> >>> EMPTY_EXPANSION(12); // Not diagnosed >>> EMPTY_EXPANSION; // Not diagnosed >>> ; // Diagnosed >>> >>> This could work provided that all empty space preceding the semicolon is >>> ignored (as the macro could be separated by space(s) or newline(s). >>> I’m not sure the complexity would be worth it, as I haven’t seen bugs >>> arising from extra semicolons and empty statements, >>> but it would take care of my use case. >>> >>> >>> Or rather when the *previous* semicolon is coming from a macro. >>> >>> I don't like this. clang is already wa-a-ay too forgiving about >>> macros, it almost ignores almost every warning in macros. >>> It was an *intentional* decision to still warn on useless ';' after >>> non-empty macros. >>> >>> >>> I think I'm confused now. This is a test case: >>> >>> NULLMACRO(v7); // OK. This could be either GOODMACRO() or >>> BETTERMACRO() situation, so we can't know we can drop it. >>> >>> So empty macro expansions should be ignored as I expected... so what >>> is being diagnosed? George, can you provide a more clear example that >>> demonstrates the issue? >>> >>> To be clear, I do *not* think this is a situation we should spend >>> effort supporting (assuming "all available warnings" really means >>> -Weverything and not something else): >>> >>> It is a problem in practice for us since we have projects which enable >>> all available warnings and also enable “-Werror”. >>> >>> >>> However, if we are diagnosing *empty* macro expansions followed by a >>> semi-colon, I think that would be unacceptably chatty and is worth >>> fixing on its own merits. >>> >>> ~Aaron >>> >>> >>> ~Aaron >>> >>> Regards, >>> George >>> >>> Roman. >>> >>> On Nov 20, 2018, at 10:59 AM, Roman Lebedev via cfe-commits < >>> cfe-commits@lists.llvm.org> wrote: >>> >>> Author: lebedevri >>> Date: Tue Nov 20 10:59:05 2018 >>> New Revision: 347339 >>> >>> URL: http://llvm.org/viewvc/llvm-project?rev=347339&view=rev >>> Log: >>> [clang][Parse] Diagnose useless null statements / empty init-statements >>> >>> Summary: >>> clang has `-Wextra-semi` (D43162), which is not dictated by the >>> currently selected standard. >>> While that is great, there is at least one more source of need-less >>> semis - 'null statements'. >>> Sometimes, they are needed: >>> ``` >>> for(int x = 0; continueToDoWork(x); x++) >>> ; // Ugly code, but the semi is needed here. >>> ``` >>> >>> But sometimes they are just there for no reason: >>> ``` >>> switch(X) { >>> case 0: >>> return -2345; >>> case 5: >>> return 0; >>> default: >>> return 42; >>> }; // <- oops >>> >>> ;;;;;;;;;;; <- OOOOPS, still not diagnosed. Clearly this is junk. >>> ``` >>> >>> Additionally: >>> ``` >>> if(; // <- empty init-statement >>> true) >>> ; >>> >>> switch (; // empty init-statement >>> x) { >>> ... >>> } >>> >>> for (; // <- empty init-statement >>> int y : S()) >>> ; >>> } >>> >>> As usual, things may or may not go sideways in the presence of macros. >>> While evaluating this diag on my codebase of interest, it was >>> unsurprisingly >>> discovered that Google Test macros are *very* prone to this. >>> And it seems many issues are deep within the GTest itself, not >>> in the snippets passed from the codebase that uses GTest. >>> >>> So after some thought, i decided not do issue a diagnostic if the semi >>> is within *any* macro, be it either from the normal header, or system >>> header. >>> >>> Fixes [[ https://bugs.llvm.org/show_bug.cgi?id=39111 | PR39111 ]] >>> >>> Reviewers: rsmith, aaron.ballman, efriedma >>> >>> Reviewed By: aaron.ballman >>> >>> Subscribers: cfe-commits >>> >>> Differential Revision: https://reviews.llvm.org/D52695 >>> >>> Added: >>> >>> >>> cfe/trunk/test/Parser/extra-semi-resulting-in-nullstmt-in-init-statement.cpp >>> cfe/trunk/test/Parser/extra-semi-resulting-in-nullstmt.cpp >>> Modified: >>> cfe/trunk/docs/ReleaseNotes.rst >>> cfe/trunk/include/clang/Basic/DiagnosticGroups.td >>> cfe/trunk/include/clang/Basic/DiagnosticParseKinds.td >>> cfe/trunk/include/clang/Parse/Parser.h >>> cfe/trunk/lib/Parse/ParseExprCXX.cpp >>> cfe/trunk/lib/Parse/ParseStmt.cpp >>> >>> Modified: cfe/trunk/docs/ReleaseNotes.rst >>> URL: >>> http://llvm.org/viewvc/llvm-project/cfe/trunk/docs/ReleaseNotes.rst?rev=347339&r1=347338&r2=347339&view=diff >>> >>> ============================================================================== >>> --- cfe/trunk/docs/ReleaseNotes.rst (original) >>> +++ cfe/trunk/docs/ReleaseNotes.rst Tue Nov 20 10:59:05 2018 >>> @@ -55,6 +55,63 @@ Major New Features >>> Improvements to Clang's diagnostics >>> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ >>> >>> +- ``-Wextra-semi-stmt`` is a new diagnostic that diagnoses extra >>> semicolons, >>> + much like ``-Wextra-semi``. This new diagnostic diagnoses all >>> *unnecessary* >>> + null statements (expression statements without an expression), >>> unless: the >>> + semicolon directly follows a macro that was expanded to nothing or if >>> the >>> + semicolon is within the macro itself. This applies to macros defined >>> in system >>> + headers as well as user-defined macros. >>> + >>> + .. code-block:: c++ >>> + >>> + #define MACRO(x) int x; >>> + #define NULLMACRO(varname) >>> + >>> + void test() { >>> + ; // <- warning: ';' with no preceding expression is a null >>> statement >>> + >>> + while (true) >>> + ; // OK, it is needed. >>> + >>> + switch (my_enum) { >>> + case E1: >>> + // stuff >>> + break; >>> + case E2: >>> + ; // OK, it is needed. >>> + } >>> + >>> + MACRO(v0;) // Extra semicolon, but within macro, so ignored. >>> + >>> + MACRO(v1); // <- warning: ';' with no preceding expression is a >>> null statement >>> + >>> + NULLMACRO(v2); // ignored, NULLMACRO expanded to nothing. >>> + } >>> + >>> +- ``-Wempty-init-stmt`` is a new diagnostic that diagnoses empty >>> init-statements >>> + of ``if``, ``switch``, ``range-based for``, unless: the semicolon >>> directly >>> + follows a macro that was expanded to nothing or if the semicolon is >>> within the >>> + macro itself (both macros from system headers, and normal macros). >>> This >>> + diagnostic is in the ``-Wextra-semi-stmt`` group and is enabled in >>> + ``-Wextra``. >>> + >>> + .. code-block:: c++ >>> + >>> + void test() { >>> + if(; // <- warning: init-statement of 'if' is a null statement >>> + true) >>> + ; >>> + >>> + switch (; // <- warning: init-statement of 'switch' is a null >>> statement >>> + x) { >>> + ... >>> + } >>> + >>> + for (; // <- warning: init-statement of 'range-based for' is a >>> null statement >>> + int y : S()) >>> + ; >>> + } >>> + >>> >>> Non-comprehensive list of changes in this release >>> ------------------------------------------------- >>> >>> Modified: cfe/trunk/include/clang/Basic/DiagnosticGroups.td >>> URL: >>> http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticGroups.td?rev=347339&r1=347338&r2=347339&view=diff >>> >>> ============================================================================== >>> --- cfe/trunk/include/clang/Basic/DiagnosticGroups.td (original) >>> +++ cfe/trunk/include/clang/Basic/DiagnosticGroups.td Tue Nov 20 >>> 10:59:05 2018 >>> @@ -162,6 +162,8 @@ def GNUEmptyStruct : DiagGroup<"gnu-empt >>> def ExtraTokens : DiagGroup<"extra-tokens">; >>> def CXX98CompatExtraSemi : DiagGroup<"c++98-compat-extra-semi">; >>> def CXX11ExtraSemi : DiagGroup<"c++11-extra-semi">; >>> +def EmptyInitStatement : DiagGroup<"empty-init-stmt">; >>> +def ExtraSemiStmt : DiagGroup<"extra-semi-stmt", [EmptyInitStatement]>; >>> def ExtraSemi : DiagGroup<"extra-semi", [CXX98CompatExtraSemi, >>> CXX11ExtraSemi]>; >>> >>> @@ -768,7 +770,8 @@ def Extra : DiagGroup<"extra", [ >>> MissingMethodReturnType, >>> SignCompare, >>> UnusedParameter, >>> - NullPointerArithmetic >>> + NullPointerArithmetic, >>> + EmptyInitStatement >>> ]>; >>> >>> def Most : DiagGroup<"most", [ >>> >>> Modified: cfe/trunk/include/clang/Basic/DiagnosticParseKinds.td >>> URL: >>> http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticParseKinds.td?rev=347339&r1=347338&r2=347339&view=diff >>> >>> ============================================================================== >>> --- cfe/trunk/include/clang/Basic/DiagnosticParseKinds.td (original) >>> +++ cfe/trunk/include/clang/Basic/DiagnosticParseKinds.td Tue Nov 20 >>> 10:59:05 2018 >>> @@ -53,6 +53,10 @@ def ext_extra_semi_cxx11 : Extension< >>> def warn_extra_semi_after_mem_fn_def : Warning< >>> "extra ';' after member function definition">, >>> InGroup<ExtraSemi>, DefaultIgnore; >>> +def warn_null_statement : Warning< >>> + "empty expression statement has no effect; " >>> + "remove unnecessary ';' to silence this warning">, >>> + InGroup<ExtraSemiStmt>, DefaultIgnore; >>> >>> def ext_thread_before : Extension<"'__thread' before '%0'">; >>> def ext_keyword_as_ident : ExtWarn< >>> @@ -554,6 +558,9 @@ def ext_for_range_init_stmt : ExtWarn< >>> def warn_cxx17_compat_for_range_init_stmt : Warning< >>> "range-based for loop initialization statements are incompatible with " >>> "C++ standards before C++2a">, DefaultIgnore, InGroup<CXXPre2aCompat>; >>> +def warn_empty_init_statement : Warning< >>> + "empty initialization statement of '%select{if|switch|range-based >>> for}0' " >>> + "has no effect">, InGroup<EmptyInitStatement>, DefaultIgnore; >>> >>> // C++ derived classes >>> def err_dup_virtual : Error<"duplicate 'virtual' in base specifier">; >>> >>> Modified: cfe/trunk/include/clang/Parse/Parser.h >>> URL: >>> http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Parse/Parser.h?rev=347339&r1=347338&r2=347339&view=diff >>> >>> ============================================================================== >>> --- cfe/trunk/include/clang/Parse/Parser.h (original) >>> +++ cfe/trunk/include/clang/Parse/Parser.h Tue Nov 20 10:59:05 2018 >>> @@ -1888,6 +1888,7 @@ private: >>> StmtResult ParseCompoundStatement(bool isStmtExpr, >>> unsigned ScopeFlags); >>> void ParseCompoundStatementLeadingPragmas(); >>> + bool ConsumeNullStmt(StmtVector &Stmts); >>> StmtResult ParseCompoundStatementBody(bool isStmtExpr = false); >>> bool ParseParenExprOrCondition(StmtResult *InitStmt, >>> Sema::ConditionResult &CondResult, >>> >>> Modified: cfe/trunk/lib/Parse/ParseExprCXX.cpp >>> URL: >>> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Parse/ParseExprCXX.cpp?rev=347339&r1=347338&r2=347339&view=diff >>> >>> ============================================================================== >>> --- cfe/trunk/lib/Parse/ParseExprCXX.cpp (original) >>> +++ cfe/trunk/lib/Parse/ParseExprCXX.cpp Tue Nov 20 10:59:05 2018 >>> @@ -1773,7 +1773,13 @@ Sema::ConditionResult Parser::ParseCXXCo >>> // if (; true); >>> if (InitStmt && Tok.is(tok::semi)) { >>> WarnOnInit(); >>> - SourceLocation SemiLoc = ConsumeToken(); >>> + SourceLocation SemiLoc = Tok.getLocation(); >>> + if (!Tok.hasLeadingEmptyMacro() && !SemiLoc.isMacroID()) { >>> + Diag(SemiLoc, diag::warn_empty_init_statement) >>> + << (CK == Sema::ConditionKind::Switch) >>> + << FixItHint::CreateRemoval(SemiLoc); >>> + } >>> + ConsumeToken(); >>> *InitStmt = Actions.ActOnNullStmt(SemiLoc); >>> return ParseCXXCondition(nullptr, Loc, CK); >>> } >>> >>> Modified: cfe/trunk/lib/Parse/ParseStmt.cpp >>> URL: >>> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Parse/ParseStmt.cpp?rev=347339&r1=347338&r2=347339&view=diff >>> >>> ============================================================================== >>> --- cfe/trunk/lib/Parse/ParseStmt.cpp (original) >>> +++ cfe/trunk/lib/Parse/ParseStmt.cpp Tue Nov 20 10:59:05 2018 >>> @@ -930,6 +930,34 @@ void Parser::ParseCompoundStatementLeadi >>> >>> } >>> >>> +/// Consume any extra semi-colons resulting in null statements, >>> +/// returning true if any tok::semi were consumed. >>> +bool Parser::ConsumeNullStmt(StmtVector &Stmts) { >>> + if (!Tok.is(tok::semi)) >>> + return false; >>> + >>> + SourceLocation StartLoc = Tok.getLocation(); >>> + SourceLocation EndLoc; >>> + >>> + while (Tok.is(tok::semi) && !Tok.hasLeadingEmptyMacro() && >>> + Tok.getLocation().isValid() && !Tok.getLocation().isMacroID()) >>> { >>> + EndLoc = Tok.getLocation(); >>> + >>> + // Don't just ConsumeToken() this tok::semi, do store it in AST. >>> + StmtResult R = ParseStatementOrDeclaration(Stmts, ACK_Any); >>> + if (R.isUsable()) >>> + Stmts.push_back(R.get()); >>> + } >>> + >>> + // Did not consume any extra semi. >>> + if (EndLoc.isInvalid()) >>> + return false; >>> + >>> + Diag(StartLoc, diag::warn_null_statement) >>> + << FixItHint::CreateRemoval(SourceRange(StartLoc, EndLoc)); >>> + return true; >>> +} >>> + >>> /// ParseCompoundStatementBody - Parse a sequence of statements and >>> invoke the >>> /// ActOnCompoundStmt action. This expects the '{' to be the current >>> token, and >>> /// consume the '}' at the end of the block. It does not manipulate the >>> scope >>> @@ -992,6 +1020,9 @@ StmtResult Parser::ParseCompoundStatemen >>> continue; >>> } >>> >>> + if (ConsumeNullStmt(Stmts)) >>> + continue; >>> + >>> StmtResult R; >>> if (Tok.isNot(tok::kw___extension__)) { >>> R = ParseStatementOrDeclaration(Stmts, ACK_Any); >>> @@ -1588,10 +1619,15 @@ StmtResult Parser::ParseForStatement(Sou >>> ParsedAttributesWithRange attrs(AttrFactory); >>> MaybeParseCXX11Attributes(attrs); >>> >>> + SourceLocation EmptyInitStmtSemiLoc; >>> + >>> // Parse the first part of the for specifier. >>> if (Tok.is(tok::semi)) { // for (; >>> ProhibitAttributes(attrs); >>> // no first part, eat the ';'. >>> + SourceLocation SemiLoc = Tok.getLocation(); >>> + if (!Tok.hasLeadingEmptyMacro() && !SemiLoc.isMacroID()) >>> + EmptyInitStmtSemiLoc = SemiLoc; >>> ConsumeToken(); >>> } else if (getLangOpts().CPlusPlus && Tok.is(tok::identifier) && >>> isForRangeIdentifier()) { >>> @@ -1723,6 +1759,11 @@ StmtResult Parser::ParseForStatement(Sou >>> : diag::ext_for_range_init_stmt) >>> << (FirstPart.get() ? FirstPart.get()->getSourceRange() >>> : SourceRange()); >>> + if (EmptyInitStmtSemiLoc.isValid()) { >>> + Diag(EmptyInitStmtSemiLoc, diag::warn_empty_init_statement) >>> + << /*for-loop*/ 2 >>> + << FixItHint::CreateRemoval(EmptyInitStmtSemiLoc); >>> + } >>> } >>> } else { >>> ExprResult SecondExpr = ParseExpression(); >>> >>> Added: >>> cfe/trunk/test/Parser/extra-semi-resulting-in-nullstmt-in-init-statement.cpp >>> URL: >>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Parser/extra-semi-resulting-in-nullstmt-in-init-statement.cpp?rev=347339&view=auto >>> >>> ============================================================================== >>> --- >>> cfe/trunk/test/Parser/extra-semi-resulting-in-nullstmt-in-init-statement.cpp >>> (added) >>> +++ >>> cfe/trunk/test/Parser/extra-semi-resulting-in-nullstmt-in-init-statement.cpp >>> Tue Nov 20 10:59:05 2018 >>> @@ -0,0 +1,64 @@ >>> +// RUN: %clang_cc1 -fsyntax-only -Wextra -std=c++2a -verify %s >>> +// RUN: %clang_cc1 -fsyntax-only -Wextra-semi-stmt -std=c++2a -verify %s >>> +// RUN: %clang_cc1 -fsyntax-only -Wempty-init-stmt -std=c++2a -verify %s >>> +// RUN: cp %s %t >>> +// RUN: %clang_cc1 -x c++ -Wempty-init-stmt -std=c++2a -fixit %t >>> +// RUN: %clang_cc1 -x c++ -Wempty-init-stmt -std=c++2a -Werror %t >>> + >>> +struct S { >>> + int *begin(); >>> + int *end(); >>> +}; >>> + >>> +void naive(int x) { >>> + if (; true) // expected-warning {{empty initialization statement of >>> 'if' has no effect}} >>> + ; >>> + >>> + switch (; x) { // expected-warning {{empty initialization statement >>> of 'switch' has no effect}} >>> + } >>> + >>> + for (; int y : S()) // expected-warning {{empty initialization >>> statement of 'range-based for' has no effect}} >>> + ; >>> + >>> + for (;;) // OK >>> + ; >>> +} >>> + >>> +#define NULLMACRO >>> + >>> +void with_null_macro(int x) { >>> + if (NULLMACRO; true) >>> + ; >>> + >>> + switch (NULLMACRO; x) { >>> + } >>> + >>> + for (NULLMACRO; int y : S()) >>> + ; >>> +} >>> + >>> +#define SEMIMACRO ; >>> + >>> +void with_semi_macro(int x) { >>> + if (SEMIMACRO true) >>> + ; >>> + >>> + switch (SEMIMACRO x) { >>> + } >>> + >>> + for (SEMIMACRO int y : S()) >>> + ; >>> +} >>> + >>> +#define PASSTHROUGHMACRO(x) x >>> + >>> +void with_passthrough_macro(int x) { >>> + if (PASSTHROUGHMACRO(;) true) >>> + ; >>> + >>> + switch (PASSTHROUGHMACRO(;) x) { >>> + } >>> + >>> + for (PASSTHROUGHMACRO(;) int y : S()) >>> + ; >>> +} >>> >>> Added: cfe/trunk/test/Parser/extra-semi-resulting-in-nullstmt.cpp >>> URL: >>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Parser/extra-semi-resulting-in-nullstmt.cpp?rev=347339&view=auto >>> >>> ============================================================================== >>> --- cfe/trunk/test/Parser/extra-semi-resulting-in-nullstmt.cpp (added) >>> +++ cfe/trunk/test/Parser/extra-semi-resulting-in-nullstmt.cpp Tue Nov >>> 20 10:59:05 2018 >>> @@ -0,0 +1,96 @@ >>> +// RUN: %clang_cc1 -fsyntax-only -Wextra-semi-stmt -verify %s >>> +// RUN: cp %s %t >>> +// RUN: %clang_cc1 -x c++ -Wextra-semi-stmt -fixit %t >>> +// RUN: %clang_cc1 -x c++ -Wextra-semi-stmt -Werror %t >>> + >>> +#define GOODMACRO(varname) int varname >>> +#define BETTERMACRO(varname) GOODMACRO(varname); >>> +#define NULLMACRO(varname) >>> + >>> +enum MyEnum { >>> + E1, >>> + E2 >>> +}; >>> + >>> +void test() { >>> + ; // expected-warning {{empty expression statement has no effect; >>> remove unnecessary ';' to silence this warning}} >>> + ; >>> + >>> + // This removal of extra semi also consumes all the comments. >>> + // clang-format: off >>> + ;;; >>> + // clang-format: on >>> + >>> + // clang-format: off >>> + ;NULLMACRO(ZZ); >>> + // clang-format: on >>> + >>> + {}; // expected-warning {{empty expression statement has no effect; >>> remove unnecessary ';' to silence this warning}} >>> + >>> + { >>> + ; // expected-warning {{empty expression statement has no effect; >>> remove unnecessary ';' to silence this warning}} >>> + } >>> + >>> + if (true) { >>> + ; // expected-warning {{empty expression statement has no effect; >>> remove unnecessary ';' to silence this warning}} >>> + } >>> + >>> + GOODMACRO(v0); // OK >>> + >>> + GOODMACRO(v1;) // OK >>> + >>> + BETTERMACRO(v2) // OK >>> + >>> + BETTERMACRO(v3;) // Extra ';', but within macro expansion, so ignored. >>> + >>> + BETTERMACRO(v4); // expected-warning {{empty expression statement has >>> no effect; remove unnecessary ';' to silence this warning}} >>> + >>> + BETTERMACRO(v5;); // expected-warning {{empty expression statement >>> has no effect; remove unnecessary ';' to silence this warning}} >>> + >>> + NULLMACRO(v6) // OK >>> + >>> + NULLMACRO(v7); // OK. This could be either GOODMACRO() or >>> BETTERMACRO() situation, so we can't know we can drop it. >>> + >>> + if (true) >>> + ; // OK >>> + >>> + while (true) >>> + ; // OK >>> + >>> + do >>> + ; // OK >>> + while (true); >>> + >>> + for (;;) // OK >>> + ; // OK >>> + >>> + MyEnum my_enum; >>> + switch (my_enum) { >>> + case E1: >>> + // stuff >>> + break; >>> + case E2:; // OK >>> + } >>> + >>> + for (;;) { >>> + for (;;) { >>> + goto contin_outer; >>> + } >>> + contin_outer:; // OK >>> + } >>> +} >>> + >>> +; >>> + >>> +namespace NS {}; >>> + >>> +void foo(int x) { >>> + switch (x) { >>> + case 0: >>> + [[fallthrough]]; >>> + case 1: >>> + return; >>> + } >>> +} >>> + >>> +[[]]; >>> >>> >>> _______________________________________________ >>> cfe-commits mailing list >>> cfe-commits@lists.llvm.org >>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits >>> >>> _______________________________________________ >>> cfe-dev mailing list >>> cfe-...@lists.llvm.org >>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev >>> >>> >>> _______________________________________________ >>> cfe-commits mailing list >>> cfe-commits@lists.llvm.org >>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits >>> >>> >>> _______________________________________________ >>> cfe-commits mailing list >>> cfe-commits@lists.llvm.org >>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits >>> >> _______________________________________________ >> cfe-dev mailing list >> cfe-...@lists.llvm.org >> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev >> > _______________________________________________ > cfe-commits mailing list > cfe-commits@lists.llvm.org > http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits >
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