r318556 - Loosen -Wempty-body warning

Hans Wennborg via cfe-commits cfe-commits at lists.llvm.org
Mon Nov 20 09:39:40 PST 2017


I've reverted in r318665 to get the buildbots green until this is figured out.



On Sat, Nov 18, 2017 at 11:55 AM, Hans Wennborg <hans at chromium.org> wrote:
> We're still seeing some in macro-related code. From Chromium:
>
> ../../third_party/ffmpeg/libavcodec/bitstream.c(169,5):  error: if
> statement has empty body [-Werror,-Wempty-body]
>     ff_dlog(NULL, "new table index=%d size=%d\n", table_index, table_size);
>     ^
> ../../third_party/ffmpeg\libavutil/internal.h(276,80):  note: expanded
> from macro 'ff_dlog'
> #   define ff_dlog(ctx, ...) do { if (0) av_log(ctx, AV_LOG_DEBUG,
> __VA_ARGS__); } while (0)
>                                                                                ^
> ../../third_party/ffmpeg/libavcodec/bitstream.c(169,5):  note: put the
> semicolon on a separate line to silence this warning
>
> (See https://build.chromium.org/p/chromium.clang/builders/ToTWin/builds/420)
>
> On Fri, Nov 17, 2017 at 1:33 PM, Reid Kleckner via cfe-commits
> <cfe-commits at lists.llvm.org> wrote:
>> Author: rnk
>> Date: Fri Nov 17 13:33:28 2017
>> New Revision: 318556
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=318556&view=rev
>> Log:
>> Loosen -Wempty-body warning
>>
>> Do not show it when `if` or `else` come from macros.
>> E.g.,
>>
>>     #define USED(A) if (A); else
>>     #define SOME_IF(A) if (A)
>>
>>     void test() {
>>       // No warnings are shown in those cases now.
>>       USED(0);
>>       SOME_IF(0);
>>     }
>>
>> Patch by Ilya Biryukov!
>>
>> Differential Revision: https://reviews.llvm.org/D40185
>>
>> Modified:
>>     cfe/trunk/include/clang/Sema/Sema.h
>>     cfe/trunk/lib/Parse/ParseStmt.cpp
>>     cfe/trunk/lib/Sema/SemaChecking.cpp
>>     cfe/trunk/lib/Sema/SemaStmt.cpp
>>     cfe/trunk/test/SemaCXX/warn-empty-body.cpp
>>
>> Modified: cfe/trunk/include/clang/Sema/Sema.h
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Sema/Sema.h?rev=318556&r1=318555&r2=318556&view=diff
>> ==============================================================================
>> --- cfe/trunk/include/clang/Sema/Sema.h (original)
>> +++ cfe/trunk/include/clang/Sema/Sema.h Fri Nov 17 13:33:28 2017
>> @@ -9690,6 +9690,7 @@ public:
>>    class ConditionResult {
>>      Decl *ConditionVar;
>>      FullExprArg Condition;
>> +    SourceLocation RParenLoc;
>>      bool Invalid;
>>      bool HasKnownValue;
>>      bool KnownValue;
>> @@ -9713,6 +9714,9 @@ public:
>>        return std::make_pair(cast_or_null<VarDecl>(ConditionVar),
>>                              Condition.get());
>>      }
>> +
>> +    void setRParenLoc(SourceLocation Loc) { RParenLoc = Loc; }
>> +
>>      llvm::Optional<bool> getKnownValue() const {
>>        if (!HasKnownValue)
>>          return None;
>>
>> Modified: cfe/trunk/lib/Parse/ParseStmt.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Parse/ParseStmt.cpp?rev=318556&r1=318555&r2=318556&view=diff
>> ==============================================================================
>> --- cfe/trunk/lib/Parse/ParseStmt.cpp (original)
>> +++ cfe/trunk/lib/Parse/ParseStmt.cpp Fri Nov 17 13:33:28 2017
>> @@ -1101,6 +1101,7 @@ bool Parser::ParseParenExprOrCondition(S
>>
>>    // Otherwise the condition is valid or the rparen is present.
>>    T.consumeClose();
>> +  Cond.setRParenLoc(T.getCloseLocation());
>>
>>    // Check for extraneous ')'s to catch things like "if (foo())) {".  We know
>>    // that all callers are looking for a statement after the condition, so ")"
>>
>> Modified: cfe/trunk/lib/Sema/SemaChecking.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaChecking.cpp?rev=318556&r1=318555&r2=318556&view=diff
>> ==============================================================================
>> --- cfe/trunk/lib/Sema/SemaChecking.cpp (original)
>> +++ cfe/trunk/lib/Sema/SemaChecking.cpp Fri Nov 17 13:33:28 2017
>> @@ -11821,7 +11821,7 @@ static bool ShouldDiagnoseEmptyStmtBody(
>>
>>    // Get line numbers of statement and body.
>>    bool StmtLineInvalid;
>> -  unsigned StmtLine = SourceMgr.getPresumedLineNumber(StmtLoc,
>> +  unsigned StmtLine = SourceMgr.getSpellingLineNumber(StmtLoc,
>>                                                        &StmtLineInvalid);
>>    if (StmtLineInvalid)
>>      return false;
>>
>> Modified: cfe/trunk/lib/Sema/SemaStmt.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaStmt.cpp?rev=318556&r1=318555&r2=318556&view=diff
>> ==============================================================================
>> --- cfe/trunk/lib/Sema/SemaStmt.cpp (original)
>> +++ cfe/trunk/lib/Sema/SemaStmt.cpp Fri Nov 17 13:33:28 2017
>> @@ -530,8 +530,7 @@ Sema::ActOnIfStmt(SourceLocation IfLoc,
>>    if (elseStmt)
>>      DiagnoseEmptyStmtBody(ElseLoc, elseStmt, diag::warn_empty_else_body);
>>    else
>> -    DiagnoseEmptyStmtBody(CondExpr->getLocEnd(), thenStmt,
>> -                          diag::warn_empty_if_body);
>> +    DiagnoseEmptyStmtBody(Cond.RParenLoc, thenStmt, diag::warn_empty_if_body);
>>
>>    return BuildIfStmt(IfLoc, IsConstexpr, InitStmt, Cond, thenStmt, ElseLoc,
>>                       elseStmt);
>>
>> Modified: cfe/trunk/test/SemaCXX/warn-empty-body.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/warn-empty-body.cpp?rev=318556&r1=318555&r2=318556&view=diff
>> ==============================================================================
>> --- cfe/trunk/test/SemaCXX/warn-empty-body.cpp (original)
>> +++ cfe/trunk/test/SemaCXX/warn-empty-body.cpp Fri Nov 17 13:33:28 2017
>> @@ -301,3 +301,14 @@ void test7(int x, int y) {
>>    if (x) IDENTITY(); // no-warning
>>  }
>>
>> +#define SOME_IF(A) if (A)
>> +#define IF_ELSE(A) if (A); else
>> +
>> +
>> +void test_macros() {
>> +  SOME_IF(0);
>> +  IF_ELSE(0);
>> +
>> +  IDENTITY(if (0);) // expected-warning{{if statement has empty body}} expected-note{{separate line}}
>> +  IDENTITY(if (0); else;) // expected-warning{{else clause has empty body}} expected-note{{separate line}}}
>> +}
>>
>>
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