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Relax header guard mismatch warning with edit distance heuristic. 

If the edit distance between the two macros is more than 50%, DefinedMacro may not be header guard or can be header guard of another header file or it might be defining something completely different set by the build environment.

llvm-svn: 192547
This commit is contained in:
Ismail Pazarbasi 2013-10-12 23:17:37 +00:00
parent 96bb15f464
commit 8d0f2f3ae3
3 changed files with 32 additions and 13 deletions
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39
clang/lib/Lex/PPLexerChange.cpp
View File

@ -264,19 +264,32 @@ bool Preprocessor::HandleEndOfFile(Token &Result, bool isEndOfMacro) {
if (!ControllingMacro->hasMacroDefinition() &&
DefinedMacro != ControllingMacro &&
HeaderInfo.FirstTimeLexingFile(FE)) {
// Emit a warning for a bad header guard.
Diag(CurPPLexer->MIOpt.GetMacroLocation(),
diag::warn_header_guard)
<< CurPPLexer->MIOpt.GetMacroLocation()
<< ControllingMacro;
Diag(CurPPLexer->MIOpt.GetDefinedLocation(),
diag::note_header_guard)
<< CurPPLexer->MIOpt.GetDefinedLocation()
<< DefinedMacro
<< ControllingMacro
<< FixItHint::CreateReplacement(
CurPPLexer->MIOpt.GetDefinedLocation(),
ControllingMacro->getName());
// If the edit distance between the two macros is more than 50%,
// DefinedMacro may not be header guard, or can be header guard of
// another header file. Therefore, it maybe defining something
// completely different. This can be observed in the wild when
// handling feature macros or header guards in different files.
const StringRef ControllingMacroName = ControllingMacro->getName();
const StringRef DefinedMacroName = DefinedMacro->getName();
const size_t MaxHalfLength = std::max(ControllingMacroName.size(),
DefinedMacroName.size()) / 2;
const unsigned ED = ControllingMacroName.edit_distance(
DefinedMacroName, true, MaxHalfLength);
if (ED <= MaxHalfLength) {
// Emit a warning for a bad header guard.
Diag(CurPPLexer->MIOpt.GetMacroLocation(),
diag::warn_header_guard)
<< CurPPLexer->MIOpt.GetMacroLocation() << ControllingMacro;
Diag(CurPPLexer->MIOpt.GetDefinedLocation(),
diag::note_header_guard)
<< CurPPLexer->MIOpt.GetDefinedLocation() << DefinedMacro
<< ControllingMacro
<< FixItHint::CreateReplacement(
CurPPLexer->MIOpt.GetDefinedLocation(),
ControllingMacro->getName());
}
}
}
}

5
clang/test/Lexer/Inputs/unlikely-to-be-header-guard.h Normal file
View File

@ -0,0 +1,5 @@
#ifndef data_rep_h
#define use_alternate_data_rep
/* #include "data_rep.h" */
#endif

1
clang/test/Lexer/header.cpp
View File

@ -6,6 +6,7 @@
#include "Inputs/different-define.h"
#include "Inputs/out-of-order-define.h"
#include "Inputs/tokens-between-ifndef-and-define.h"
#include "Inputs/unlikely-to-be-header-guard.h"
#include "Inputs/bad-header-guard.h"
// CHECK: In file included from {{.*}}header.cpp:{{[0-9]*}}: