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When targeting Windows, the path separator used when targeting Windows
depends on the build environment when Clang _itself_ is built. This
leads to inconsistencies in Chrome builds where Clang running on
non-Windows environments uses the forward slash (/) path separator
while Clang running on Windows builds uses the backslash (\) path
separator. To fix this, we make Clang use forward slashes whenever it is
targeting Windows.
We chose to use forward slashes instead of backslashes in builds
targeting Windows because according to the C standard, backslashes in
\#include directives result in undefined behavior[1]. We may change this
decision though depending on the review.
[0]: https://crbug.com/1310767
[1]: https://stackoverflow.com/a/5790259
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D123101
Files:
clang/include/clang/Basic/LangOptions.h
clang/include/clang/Lex/Preprocessor.h
clang/lib/AST/Expr.cpp
clang/lib/Basic/LangOptions.cpp
clang/lib/Lex/PPMacroExpansion.cpp
clang/test/Preprocessor/file_test_windows.c
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actor(@ayzhao) application(Differential) author(@ayzhao) herald(H223)
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subscriber(@dexonsmith) tag(#all) tag(#clang) via(conduit)
Index: clang/test/Preprocessor/file_test_windows.c
===================================================================
--- clang/test/Preprocessor/file_test_windows.c
+++ clang/test/Preprocessor/file_test_windows.c
@@ -8,19 +8,19 @@
filename: __FILE__
#include "Inputs/include-file-test/file_test.h"
-// CHECK: filename: "A:\\UNLIKELY_PATH\\empty\\file_test_windows.c"
-// CHECK: filename: "A:\\UNLIKELY_PATH\\empty/Inputs/include-file-test/file_test.h"
-// CHECK: basefile: "A:\\UNLIKELY_PATH\\empty\\file_test_windows.c"
+// CHECK: filename: "A:/UNLIKELY_PATH/empty/file_test_windows.c"
+// CHECK: filename: "A:/UNLIKELY_PATH/empty/Inputs/include-file-test/file_test.h"
+// CHECK: basefile: "A:/UNLIKELY_PATH/empty/file_test_windows.c"
// CHECK-NOT: filename:
-// CHECK-EVIL: filename: "A:\\UNLIKELY_PATH=empty\\file_test_windows.c"
-// CHECK-EVIL: filename: "A:\\UNLIKELY_PATH=empty/Inputs/include-file-test/file_test.h"
-// CHECK-EVIL: basefile: "A:\\UNLIKELY_PATH=empty\\file_test_windows.c"
+// CHECK-EVIL: filename: "A:/UNLIKELY_PATH=empty/file_test_windows.c"
+// CHECK-EVIL: filename: "A:/UNLIKELY_PATH=empty/Inputs/include-file-test/file_test.h"
+// CHECK-EVIL: basefile: "A:/UNLIKELY_PATH=empty/file_test_windows.c"
// CHECK-EVIL-NOT: filename:
-// CHECK-CASE: filename: "A:\\UNLIKELY_PATH_BASE\\file_test_windows.c"
-// CHECK-CASE: filename: "A:\\UNLIKELY_PATH_INC\\include-file-test/file_test.h"
-// CHECK-CASE: basefile: "A:\\UNLIKELY_PATH_BASE\\file_test_windows.c"
+// CHECK-CASE: filename: "A:/UNLIKELY_PATH_BASE/file_test_windows.c"
+// CHECK-CASE: filename: "A:/UNLIKELY_PATH_INC/include-file-test/file_test.h"
+// CHECK-CASE: basefile: "A:/UNLIKELY_PATH_BASE/file_test_windows.c"
// CHECK-CASE-NOT: filename:
// CHECK-REMOVE: filename: "file_test_windows.c"
Index: clang/lib/Lex/PPMacroExpansion.cpp
===================================================================
--- clang/lib/Lex/PPMacroExpansion.cpp
+++ clang/lib/Lex/PPMacroExpansion.cpp
@@ -1511,7 +1511,7 @@
} else {
FN += PLoc.getFilename();
}
- getLangOpts().remapPathPrefix(FN);
+ processPathForFileMacro(FN, getLangOpts(), getTargetInfo());
Lexer::Stringify(FN);
OS << '"' << FN << '"';
}
@@ -1886,3 +1886,18 @@
WarnUnusedMacroLocs.erase(MI->getDefinitionLoc());
MI->setIsUsed(true);
}
+
+void Preprocessor::processPathForFileMacro(SmallVectorImpl<char> &Path,
+ const LangOptions &LangOpts,
+ const TargetInfo &TI) {
+ LangOpts.remapPathPrefix(Path);
+ if (TI.getTriple().isOSWindows()) {
+ // The path separator character depends on the environment where Clang
+ // _itself_ is built (backslash for Windows, forward slash for *nix). To
+ // make the output of the __FILE__ macro deterministic, we make the path
+ // use forward slashes when targeting Windows independently of how Clang is
+ // built.
+ llvm::sys::path::make_preferred(Path,
+ llvm::sys::path::Style::windows_slash);
+ }
+}
Index: clang/lib/Basic/LangOptions.cpp
===================================================================
--- clang/lib/Basic/LangOptions.cpp
+++ clang/lib/Basic/LangOptions.cpp
@@ -62,7 +62,7 @@
llvm_unreachable("Unknown OpenCL version");
}
-void LangOptions::remapPathPrefix(SmallString<256> &Path) const {
+void LangOptions::remapPathPrefix(SmallVectorImpl<char> &Path) const {
for (const auto &Entry : MacroPrefixMap)
if (llvm::sys::path::replace_path_prefix(Path, Entry.first, Entry.second))
break;
Index: clang/lib/AST/Expr.cpp
===================================================================
--- clang/lib/AST/Expr.cpp
+++ clang/lib/AST/Expr.cpp
@@ -31,6 +31,7 @@
#include "clang/Basic/TargetInfo.h"
#include "clang/Lex/Lexer.h"
#include "clang/Lex/LiteralSupport.h"
+#include "clang/Lex/Preprocessor.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/raw_ostream.h"
@@ -2190,7 +2191,8 @@
switch (getIdentKind()) {
case SourceLocExpr::File: {
SmallString<256> Path(PLoc.getFilename());
- Ctx.getLangOpts().remapPathPrefix(Path);
+ clang::Preprocessor::processPathForFileMacro(Path, Ctx.getLangOpts(),
+ Ctx.getTargetInfo());
return MakeStringLiteral(Path);
}
case SourceLocExpr::Function: {
@@ -2223,7 +2225,8 @@
StringRef Name = F->getName();
if (Name == "_M_file_name") {
SmallString<256> Path(PLoc.getFilename());
- Ctx.getLangOpts().remapPathPrefix(Path);
+ clang::Preprocessor::processPathForFileMacro(Path, Ctx.getLangOpts(),
+ Ctx.getTargetInfo());
Value.getStructField(F->getFieldIndex()) = MakeStringLiteral(Path);
} else if (Name == "_M_function_name") {
// Note: this emits the PrettyFunction name -- different than what
Index: clang/include/clang/Lex/Preprocessor.h
===================================================================
--- clang/include/clang/Lex/Preprocessor.h
+++ clang/include/clang/Lex/Preprocessor.h
@@ -2582,6 +2582,10 @@
emitRestrictExpansionWarning(Identifier);
}
+ static void processPathForFileMacro(SmallVectorImpl<char> &Path,
+ const LangOptions &LangOpts,
+ const TargetInfo &TI);
+
private:
void emitMacroDeprecationWarning(const Token &Identifier) const;
void emitRestrictExpansionWarning(const Token &Identifier) const;
Index: clang/include/clang/Basic/LangOptions.h
===================================================================
--- clang/include/clang/Basic/LangOptions.h
+++ clang/include/clang/Basic/LangOptions.h
@@ -538,7 +538,7 @@
bool isSYCL() const { return SYCLIsDevice || SYCLIsHost; }
/// Remap path prefix according to -fmacro-prefix-path option.
- void remapPathPrefix(SmallString<256> &Path) const;
+ void remapPathPrefix(SmallVectorImpl<char> &Path) const;
};
/// Floating point control options
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