sammccall created this revision.
sammccall added a reviewer: kadircet.
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Herald added a project: clang.
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This is motivated by tooling (clangd, libclang etc) - headers without
declarations are legitimate even if they're not valid TUs.
The other use -x c-header cases (PCH/modules) are nonstandard anyway and this
warning doesn't seem necessary there either.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D85789
Files:
clang/lib/Parse/Parser.cpp
clang/test/Parser/empty-translation-unit.c
Index: clang/test/Parser/empty-translation-unit.c
===================================================================
--- clang/test/Parser/empty-translation-unit.c
+++ clang/test/Parser/empty-translation-unit.c
@@ -1,4 +1,5 @@
// RUN: %clang_cc1 -fsyntax-only -std=c99 -pedantic -W -verify %s
+// RUN: %clang_cc1 -fsyntax-only -x c-header -std=c99 -pedantic-errors -W %s
// RUN: %clang_cc1 -fsyntax-only -x c++ -std=c++03 -pedantic-errors -W %s
#include "completely-empty-header-file.h"
@@ -6,5 +7,5 @@
#define A_MACRO_IS_NOT_GOOD_ENOUGH 1
-// In C we should get this warning, but in C++ we shouldn't.
+// In C we should get this warning, but in C++ (or a header) we shouldn't.
// expected-warning{{ISO C requires a translation unit to contain at least one
declaration}}
Index: clang/lib/Parse/Parser.cpp
===================================================================
--- clang/lib/Parse/Parser.cpp
+++ clang/lib/Parse/Parser.cpp
@@ -552,9 +552,10 @@
// declaration. C++ doesn't have this restriction. We also don't want to
// complain if we have a precompiled header, although technically if the PCH
// is empty we should still emit the (pedantic) diagnostic.
+ // If the main file is a header, we're only pretending it's a TU; don't warn.
bool NoTopLevelDecls = ParseTopLevelDecl(Result, true);
if (NoTopLevelDecls && !Actions.getASTContext().getExternalSource() &&
- !getLangOpts().CPlusPlus)
+ !getLangOpts().CPlusPlus && !getLangOpts().IsHeaderFile)
Diag(diag::ext_empty_translation_unit);
return NoTopLevelDecls;
Index: clang/test/Parser/empty-translation-unit.c
===================================================================
--- clang/test/Parser/empty-translation-unit.c
+++ clang/test/Parser/empty-translation-unit.c
@@ -1,4 +1,5 @@
// RUN: %clang_cc1 -fsyntax-only -std=c99 -pedantic -W -verify %s
+// RUN: %clang_cc1 -fsyntax-only -x c-header -std=c99 -pedantic-errors -W %s
// RUN: %clang_cc1 -fsyntax-only -x c++ -std=c++03 -pedantic-errors -W %s
#include "completely-empty-header-file.h"
@@ -6,5 +7,5 @@
#define A_MACRO_IS_NOT_GOOD_ENOUGH 1
-// In C we should get this warning, but in C++ we shouldn't.
+// In C we should get this warning, but in C++ (or a header) we shouldn't.
// expected-warning{{ISO C requires a translation unit to contain at least one declaration}}
Index: clang/lib/Parse/Parser.cpp
===================================================================
--- clang/lib/Parse/Parser.cpp
+++ clang/lib/Parse/Parser.cpp
@@ -552,9 +552,10 @@
// declaration. C++ doesn't have this restriction. We also don't want to
// complain if we have a precompiled header, although technically if the PCH
// is empty we should still emit the (pedantic) diagnostic.
+ // If the main file is a header, we're only pretending it's a TU; don't warn.
bool NoTopLevelDecls = ParseTopLevelDecl(Result, true);
if (NoTopLevelDecls && !Actions.getASTContext().getExternalSource() &&
- !getLangOpts().CPlusPlus)
+ !getLangOpts().CPlusPlus && !getLangOpts().IsHeaderFile)
Diag(diag::ext_empty_translation_unit);
return NoTopLevelDecls;
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