From 0d779704f90b773e2c079447ac0e2ee784b56423 Mon Sep 17 00:00:00 2001
From: Richard Smith <richard-llvm@metafoo.co.uk>
Date: Wed, 22 Jan 2014 01:43:19 +0000
Subject: [PATCH] Enforce restrictions that 'main' is not allowed to be
deleted, or to be used by the program, in C++. (We allow the latter as an
extension, since we've always permitted it, and GCC does the same, and our
supported C++ ABIs don't do anything special in main.)
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@199782 91177308-0d34-0410-b5e6-96231b3b80d8
---
include/clang/Basic/DiagnosticSemaKinds.td | 3 +++
lib/Sema/SemaDecl.cpp | 7 +++++--
lib/Sema/SemaDeclCXX.cpp | 5 +++++
lib/Sema/SemaExpr.cpp | 7 ++++++-
4 files changed, 19 insertions(+), 3 deletions(-)
diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td
index ac5b406b801..e9780430e64 100644
--- a/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/include/clang/Basic/DiagnosticSemaKinds.td
@@ -425,6 +425,7 @@ def ext_noreturn_main : ExtWarn<
def note_main_remove_noreturn : Note<"remove '_Noreturn'">;
def err_constexpr_main : Error<
"'main' is not allowed to be declared constexpr">;
+def err_deleted_main : Error<"'main' is not allowed to be deleted">;
def err_mainlike_template_decl : Error<"%0 cannot be a template">;
def err_main_returns_nonint : Error<"'main' must return 'int'">;
def ext_main_returns_nonint : ExtWarn<"return type of 'main' is not 'int'">,
@@ -437,6 +438,8 @@ def warn_main_one_arg : Warning<"only one parameter on 'main' declaration">,
def err_main_arg_wrong : Error<"%select{first|second|third|fourth}0 "
"parameter of 'main' (%select{argument count|argument array|environment|"
"platform-specific data}0) must be of type %1">;
+def ext_main_used : Extension<
+ "ISO C++ does not allow 'main' to be used by a program">, InGroup<Main>;
/// parser diagnostics
def ext_no_declarators : ExtWarn<"declaration does not declare anything">,
diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index c08d87d59a8..9dac4d53024 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -6809,6 +6809,8 @@ Sema::ActOnFunctionDeclarator(Scope *S, Declarator &D, DeclContext *DC,
}
// If a function is defined as defaulted or deleted, mark it as such now.
+ // FIXME: Does this ever happen? ActOnStartOfFunctionDef forces the function
+ // definition kind to FDK_Definition.
switch (D.getFunctionDefinitionKind()) {
case FDK_Declaration:
case FDK_Definition:
@@ -7670,8 +7672,9 @@ static SourceRange getResultSourceRange(const FunctionDecl *FD) {
}
void Sema::CheckMain(FunctionDecl* FD, const DeclSpec& DS) {
- // C++11 [basic.start.main]p3: A program that declares main to be inline,
- // static or constexpr is ill-formed.
+ // C++11 [basic.start.main]p3:
+ // A program that [...] declares main to be inline, static or
+ // constexpr is ill-formed.
// C11 6.7.4p4: In a hosted environment, no function specifier(s) shall
// appear in a declaration of main.
// static main is not an error under C99, but we should warn about it.
diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index 39d71e20163..76b9d669d42 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -11984,6 +11984,11 @@ void Sema::SetDeclDeleted(Decl *Dcl, SourceLocation DelLoc) {
}
}
+ // C++11 [basic.start.main]p3:
+ // A program that defines main as deleted [...] is ill-formed.
+ if (Fn->isMain())
+ Diag(DelLoc, diag::err_deleted_main);
+
Fn->setDeletedAsWritten();
}
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 3640c5ad24b..ff54b6b24e4 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -264,13 +264,18 @@ bool Sema::DiagnoseUseOfDecl(NamedDecl *D, SourceLocation Loc,
SmallVectorImpl<PartialDiagnosticAt> &Suppressed = Pos->second;
for (unsigned I = 0, N = Suppressed.size(); I != N; ++I)
Diag(Suppressed[I].first, Suppressed[I].second);
-
+
// Clear out the list of suppressed diagnostics, so that we don't emit
// them again for this specialization. However, we don't obsolete this
// entry from the table, because we want to avoid ever emitting these
// diagnostics again.
Suppressed.clear();
}
+
+ // C++ [basic.start.main]p3:
+ // The function 'main' shall not be used within a program.
+ if (cast<FunctionDecl>(D)->isMain())
+ Diag(Loc, diag::ext_main_used);
}
// See if this is an auto-typed variable whose initializer we are parsing.
--
GitLab