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When the -fdirectives-only option is used together with -E, the preprocessor
output reflects evaluation of if/then/else directives.
As such, it preserves defines and undefs of macros that are still live after
such processing. The intent is that this output could be consumed as input
to generate considered a C++20 header unit.
We strip out any (unused) defines that come from built-in, built-in-file or
command line; these are re-added when the preprocessed source is consumed.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D121099
Files:
clang/include/clang/Driver/Options.td
clang/include/clang/Frontend/PreprocessorOutputOptions.h
clang/lib/Frontend/CompilerInvocation.cpp
clang/lib/Frontend/PrintPreprocessedOutput.cpp
clang/test/Modules/cxx20-hu-05.cpp
Index: clang/test/Modules/cxx20-hu-05.cpp
===================================================================
--- /dev/null
+++ clang/test/Modules/cxx20-hu-05.cpp
@@ -0,0 +1,68 @@
+// Test check that consuming -E -fdirectives-only output produces the expected
+// header unit.
+
+// RUN: rm -rf %t
+// RUN: mkdir -p %t
+// RUN: split-file %s %t
+// RUN: cd %t
+
+// RUN: %clang_cc1 -std=c++20 -E -fdirectives-only -xc++-user-header hu-01.h \
+// RUN: -o hu-01.iih
+
+// RUN: %clang_cc1 -std=c++20 -emit-header-unit \
+// RUN: -xc++-user-header-cpp-output hu-01.iih -o hu-01.pcm
+
+// RUN: %clang_cc1 -std=c++20 -emit-header-unit -xc++-user-header hu-02.h \
+// RUN: -DFOO -fmodule-file=hu-01.pcm -o hu-02.pcm -Rmodule-import 2>&1 | \
+// RUN: FileCheck --check-prefix=CHECK-IMP %s -DTDIR=%t
+
+//--- hu-01.h
+#ifndef __GUARD
+#define __GUARD
+
+int baz(int);
+#define FORTYTWO 42
+
+#define SHOULD_NOT_BE_DEFINED -1
+#undef SHOULD_NOT_BE_DEFINED
+
+#endif // __GUARD
+// expected-no-diagnostics
+
+//--- hu-02.h
+export import "hu-01.h";
+#if !defined(FORTYTWO) || FORTYTWO != 42
+#error FORTYTWO missing in hu-02
+#endif
+
+#ifndef __GUARD
+#error __GUARD missing in hu-02
+#endif
+
+#ifdef SHOULD_NOT_BE_DEFINED
+#error SHOULD_NOT_BE_DEFINED is visible
+#endif
+
+// Make sure that we have not discarded macros from the builtin file.
+#ifndef __cplusplus
+#error we dropped a defined macro
+#endif
+
+#define KAP 6174
+
+#ifdef FOO
+#define FOO_BRANCH(X) (X) + 1
+inline int foo(int x) {
+ if (x == FORTYTWO)
+ return FOO_BRANCH(x);
+ return FORTYTWO;
+}
+#else
+#define BAR_BRANCH(X) (X) + 2
+inline int bar(int x) {
+ if (x == FORTYTWO)
+ return BAR_BRANCH(x);
+ return FORTYTWO;
+}
+#endif
+// CHECK-IMP: remark: importing module './hu-01.h' from 'hu-01.pcm'
Index: clang/lib/Frontend/PrintPreprocessedOutput.cpp
===================================================================
--- clang/lib/Frontend/PrintPreprocessedOutput.cpp
+++ clang/lib/Frontend/PrintPreprocessedOutput.cpp
@@ -96,6 +96,7 @@
bool UseLineDirectives;
bool IsFirstFileEntered;
bool MinimizeWhitespace;
+ bool DirectivesOnly;
Token PrevTok;
Token PrevPrevTok;
@@ -103,12 +104,13 @@
public:
PrintPPOutputPPCallbacks(Preprocessor &pp, raw_ostream &os, bool lineMarkers,
bool defines, bool DumpIncludeDirectives,
- bool UseLineDirectives, bool MinimizeWhitespace)
+ bool UseLineDirectives, bool MinimizeWhitespace,
+ bool DirectivesOnly)
: PP(pp), SM(PP.getSourceManager()), ConcatInfo(PP), OS(os),
DisableLineMarkers(lineMarkers), DumpDefines(defines),
DumpIncludeDirectives(DumpIncludeDirectives),
UseLineDirectives(UseLineDirectives),
- MinimizeWhitespace(MinimizeWhitespace) {
+ MinimizeWhitespace(MinimizeWhitespace), DirectivesOnly(DirectivesOnly) {
CurLine = 0;
CurFilename += "<uninit>";
EmittedTokensOnThisLine = false;
@@ -467,12 +469,21 @@
void PrintPPOutputPPCallbacks::MacroDefined(const Token &MacroNameTok,
const MacroDirective *MD) {
const MacroInfo *MI = MD->getMacroInfo();
- // Only print out macro definitions in -dD mode.
- if (!DumpDefines ||
+ // Print out macro definitions in -dD mode and when we have -fdirectives-only
+ // for C++20 header units.
+ if ((!DumpDefines && !DirectivesOnly) ||
// Ignore __FILE__ etc.
- MI->isBuiltinMacro()) return;
+ MI->isBuiltinMacro())
+ return;
- MoveToLine(MI->getDefinitionLoc(), /*RequireStartOfLine=*/true);
+ SourceLocation DefLoc = MI->getDefinitionLoc();
+ if (DirectivesOnly && !MI->isUsed()) {
+ SourceManager &SM = PP.getSourceManager();
+ if (SM.isWrittenInBuiltinFile(DefLoc) ||
+ SM.isWrittenInCommandLineFile(DefLoc))
+ return;
+ }
+ MoveToLine(DefLoc, /*RequireStartOfLine=*/true);
PrintMacroDefinition(*MacroNameTok.getIdentifierInfo(), *MI, PP, OS);
setEmittedDirectiveOnThisLine();
}
@@ -480,8 +491,10 @@
void PrintPPOutputPPCallbacks::MacroUndefined(const Token &MacroNameTok,
const MacroDefinition &MD,
const MacroDirective *Undef) {
- // Only print out macro definitions in -dD mode.
- if (!DumpDefines) return;
+ // Print out macro definitions in -dD mode and when we have -fdirectives-only
+ // for C++20 header units.
+ if (!DumpDefines && !DirectivesOnly)
+ return;
MoveToLine(MacroNameTok.getLocation(), /*RequireStartOfLine=*/true);
OS << "#undef " << MacroNameTok.getIdentifierInfo()->getName();
@@ -959,7 +972,7 @@
PrintPPOutputPPCallbacks *Callbacks = new PrintPPOutputPPCallbacks(
PP, *OS, !Opts.ShowLineMarkers, Opts.ShowMacros,
Opts.ShowIncludeDirectives, Opts.UseLineDirectives,
- Opts.MinimizeWhitespace);
+ Opts.MinimizeWhitespace, Opts.DirectivesOnly);
// Expand macros in pragmas with -fms-extensions. The assumption is that
// the majority of pragmas in such a file will be Microsoft pragmas.
@@ -995,6 +1008,8 @@
// After we have configured the preprocessor, enter the main file.
PP.EnterMainSourceFile();
+ if (Opts.DirectivesOnly)
+ PP.SetMacroExpansionOnlyInDirectives();
// Consume all of the tokens that come from the predefines buffer. Those
// should not be emitted into the output and are guaranteed to be at the
Index: clang/lib/Frontend/CompilerInvocation.cpp
===================================================================
--- clang/lib/Frontend/CompilerInvocation.cpp
+++ clang/lib/Frontend/CompilerInvocation.cpp
@@ -4412,6 +4412,8 @@
GenerateArg(Args, OPT_dM, SA);
if (!Generate_dM && Opts.ShowMacros)
GenerateArg(Args, OPT_dD, SA);
+ if (Opts.DirectivesOnly)
+ GenerateArg(Args, OPT_fdirectives_only, SA);
}
static bool ParsePreprocessorOutputArgs(PreprocessorOutputOptions &Opts,
@@ -4434,6 +4436,7 @@
Opts.ShowCPP = isStrictlyPreprocessorAction(Action) && !Args.hasArg(OPT_dM);
Opts.ShowMacros = Args.hasArg(OPT_dM) || Args.hasArg(OPT_dD);
+ Opts.DirectivesOnly = Args.hasArg(OPT_fdirectives_only);
return Diags.getNumErrors() == NumErrorsBefore;
}
Index: clang/include/clang/Frontend/PreprocessorOutputOptions.h
===================================================================
--- clang/include/clang/Frontend/PreprocessorOutputOptions.h
+++ clang/include/clang/Frontend/PreprocessorOutputOptions.h
@@ -25,6 +25,7 @@
unsigned RewriteIncludes : 1; ///< Preprocess include directives only.
unsigned RewriteImports : 1; ///< Include contents of transitively-imported modules.
unsigned MinimizeWhitespace : 1; ///< Ignore whitespace from input.
+ unsigned DirectivesOnly : 1; ///< Process directives but do not expand macros.
public:
PreprocessorOutputOptions() {
@@ -38,6 +39,7 @@
RewriteIncludes = 0;
RewriteImports = 0;
MinimizeWhitespace = 0;
+ DirectivesOnly = 0;
}
};
Index: clang/include/clang/Driver/Options.td
===================================================================
--- clang/include/clang/Driver/Options.td
+++ clang/include/clang/Driver/Options.td
@@ -1874,6 +1874,8 @@
PreprocessorOutputOpts<"RewriteIncludes">, DefaultFalse,
PosFlag<SetTrue, [CC1Option]>, NegFlag<SetFalse>>;
+defm directives_only : OptInCC1FFlag<"directives-only", "">;
+
defm delete_null_pointer_checks : BoolFOption<"delete-null-pointer-checks",
CodeGenOpts<"NullPointerIsValid">, DefaultFalse,
NegFlag<SetTrue, [CC1Option], "Do not treat usage of null pointers as undefined behavior">,
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