aaron.ballman updated this revision to Diff 423629.
aaron.ballman marked an inline comment as not done.
aaron.ballman added a comment.
Updated based on review feedback.
- Added `-fstrict-prototypes` command line option (but there is NO
`-fno-strict-prototypes` support)
- Changed the way the language option works to be a little less fragile
- Fixed the static analyzer to create a function with a prototype instead
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D123955/new/
https://reviews.llvm.org/D123955
Files:
clang/docs/ReleaseNotes.rst
clang/include/clang/Basic/LangOptions.def
clang/include/clang/Basic/LangOptions.h
clang/include/clang/Driver/Options.td
clang/lib/AST/ASTContext.cpp
clang/lib/Parse/ParseDecl.cpp
clang/lib/Sema/SemaDecl.cpp
clang/lib/Sema/SemaType.cpp
clang/lib/StaticAnalyzer/Core/MemRegion.cpp
clang/test/Driver/strict-prototypes.c
clang/test/Frontend/strict-prototypes.c
clang/test/Parser/c2x-attributes.c
clang/test/Parser/c2x-func-prototype.c
clang/test/Sema/attr-c2x.c
clang/test/Sema/c2x-func-prototype.c
clang/www/c_status.html
Index: clang/www/c_status.html
===================================================================
--- clang/www/c_status.html
+++ clang/www/c_status.html
@@ -725,7 +725,7 @@
<tr>
<td>Remove support for function definitions with identifier lists</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2432.pdf";>N2432</a></td>
- <td class="none" align="center">No</td>
+ <td class="unreleased" align="center">Clang 15</td>
</tr>
<!-- Oct 2019 Papers -->
<tr>
Index: clang/test/Sema/c2x-func-prototype.c
===================================================================
--- /dev/null
+++ clang/test/Sema/c2x-func-prototype.c
@@ -0,0 +1,24 @@
+// RUN: %clang_cc1 -fsyntax-only -verify=c2x -std=c2x %s
+// RUN: %clang_cc1 -Wno-strict-prototypes -fsyntax-only -verify -std=c17 %s
+// RUN: %clang_cc1 -fsyntax-only -fstrict-prototypes -std=c99 -verify=c2x %s
+// expected-no-diagnostics
+
+void func(); // c2x-note {{'func' declared here}}
+typedef void (*fp)();
+
+void other_func(int i);
+
+void call(void) {
+ func(1, 2, 3); // c2x-error {{too many arguments to function call, expected 0, have 3}}
+ fp call_me = func;
+ call_me(1, 2, 3); // c2x-error {{too many arguments to function call, expected 0, have 3}}
+
+ fp nope = other_func; // c2x-warning {{incompatible function pointer types initializing 'fp' (aka 'void (*)(void)') with an expression of type 'void (int)'}}
+}
+
+// Ensure these function declarations do not merge in C2x.
+void redecl1(); // c2x-note {{previous declaration is here}}
+void redecl1(int i); // c2x-error {{conflicting types for 'redecl1'}}
+
+void redecl2(int i); // c2x-note {{previous declaration is here}}
+void redecl2(); // c2x-error {{conflicting types for 'redecl2'}}
Index: clang/test/Sema/attr-c2x.c
===================================================================
--- clang/test/Sema/attr-c2x.c
+++ clang/test/Sema/attr-c2x.c
@@ -20,7 +20,7 @@
void context_async_okay2(void *context [[clang::swift_async_context]], void *selfType, char **selfWitnessTable) [[clang::swiftasynccall]];
[[clang::ownership_returns(foo)]] void *f1(void);
-[[clang::ownership_returns(foo)]] void *f2(); // expected-warning {{'ownership_returns' attribute only applies to non-K&R-style functions}}
+[[clang::ownership_returns(foo)]] void *f2();
[[clang::unavailable("not available - replaced")]] void foo2(void); // expected-note {{'foo2' has been explicitly marked unavailable here}}
void bar(void) {
Index: clang/test/Parser/c2x-func-prototype.c
===================================================================
--- /dev/null
+++ clang/test/Parser/c2x-func-prototype.c
@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 -fsyntax-only -verify=c2x -std=c2x %s
+// RUN: %clang_cc1 -Wno-strict-prototypes -fsyntax-only -verify -std=c17 %s
+// expected-no-diagnostics
+
+// Functions with an identifier list are not supported in C2x.
+void ident_list(a) // c2x-error {{expected ';' after top level declarator}} \
+ c2x-warning {{type specifier missing, defaults to 'int'}}
+ int a;
+{} // c2x-error {{expected identifier or '('}}
+
+// Functions with an empty parameter list are supported as though the function
+// was declared with a parameter list of (void). Ensure they still parse.
+void no_param_decl();
+void no_param_defn() {}
+void (*var_of_type_with_no_param)();
+typedef void fn();
Index: clang/test/Parser/c2x-attributes.c
===================================================================
--- clang/test/Parser/c2x-attributes.c
+++ clang/test/Parser/c2x-attributes.c
@@ -1,5 +1,5 @@
-// RUN: %clang_cc1 -fsyntax-only -fdouble-square-bracket-attributes -verify -Wno-strict-prototypes %s
-// RUN: %clang_cc1 -fsyntax-only -std=gnu2x -verify -Wno-strict-prototypes %s
+// RUN: %clang_cc1 -fsyntax-only -fdouble-square-bracket-attributes -verify=expected,notc2x -Wno-strict-prototypes %s
+// RUN: %clang_cc1 -fsyntax-only -std=gnu2x -verify=expected,c2x %s
enum [[]] E {
One [[]],
@@ -59,7 +59,10 @@
void f5(int i [[]], [[]] int j, int [[]] k);
-void f6(a, b) [[]] int a; int b; { // expected-error {{an attribute list cannot appear here}}
+void f6(a, b) [[]] int a; int b; { // notc2x-error {{an attribute list cannot appear here}} \
+ c2x-warning 2 {{type specifier missing, defaults to 'int'}} \
+ c2x-error {{expected ';' after top level declarator}} \
+ c2x-error {{expected identifier or '('}}
}
// FIXME: technically, an attribute list cannot appear here, but we currently
@@ -67,7 +70,10 @@
// behavior given that we *don't* want to parse it as part of the K&R parameter
// declarations. It is disallowed to avoid a parsing ambiguity we already
// handle well.
-int (*f7(a, b))(int, int) [[]] int a; int b; {
+int (*f7(a, b))(int, int) [[]] int a; int b; { // c2x-warning 2 {{type specifier missing, defaults to 'int'}} \
+ c2x-error {{expected ';' after top level declarator}} \
+ c2x-error {{expected identifier or '('}}
+
return 0;
}
Index: clang/test/Frontend/strict-prototypes.c
===================================================================
--- /dev/null
+++ clang/test/Frontend/strict-prototypes.c
@@ -0,0 +1,8 @@
+// Ensure that we cannot disable strict prototypes, no matter how hard we try.
+
+// RUN: not %clang_cc1 -fno-strict-prototypes -x c++ %s 2>&1 | FileCheck %s
+// RUN: not %clang_cc1 -fno-strict-prototypes -x c %s 2>&1 | FileCheck %s
+// RUN: not %clang_cc1 -fno-strict-prototypes -std=c89 -x c %s 2>&1 | FileCheck %s
+
+// CHECK: error: unknown argument: '-fno-strict-prototypes'
+
Index: clang/test/Driver/strict-prototypes.c
===================================================================
--- /dev/null
+++ clang/test/Driver/strict-prototypes.c
@@ -0,0 +1,8 @@
+// Ensure that we cannot disable strict prototypes, no matter how hard we try.
+
+// RUN: not %clang -fno-strict-prototypes -x c++ %s 2>&1 | FileCheck %s
+// RUN: not %clang -fno-strict-prototypes -x c %s 2>&1 | FileCheck %s
+// RUN: not %clang -fno-strict-prototypes -std=c89 -x c %s 2>&1 | FileCheck %s
+
+// CHECK: error: unknown argument: '-fno-strict-prototypes'
+
Index: clang/lib/StaticAnalyzer/Core/MemRegion.cpp
===================================================================
--- clang/lib/StaticAnalyzer/Core/MemRegion.cpp
+++ clang/lib/StaticAnalyzer/Core/MemRegion.cpp
@@ -1033,8 +1033,10 @@
T = TSI->getType();
if (T.isNull())
T = getContext().VoidTy;
- if (!T->getAs<FunctionType>())
- T = getContext().getFunctionNoProtoType(T);
+ if (!T->getAs<FunctionType>()) {
+ FunctionProtoType::ExtProtoInfo Ext;
+ T = getContext().getFunctionType(T, None, Ext);
+ }
T = getContext().getBlockPointerType(T);
const BlockCodeRegion *BTR =
Index: clang/lib/Sema/SemaType.cpp
===================================================================
--- clang/lib/Sema/SemaType.cpp
+++ clang/lib/Sema/SemaType.cpp
@@ -5270,8 +5270,11 @@
FunctionType::ExtInfo EI(
getCCForDeclaratorChunk(S, D, DeclType.getAttrs(), FTI, chunkIndex));
- if (!FTI.NumParams && !FTI.isVariadic && !LangOpts.CPlusPlus
- && !LangOpts.OpenCL) {
+ // OpenCL disallows functions without a prototype, but it doesn't enforce
+ // strict prototypes as in C2x because it allows a function definition to
+ // have an identifier list.
+ if (!FTI.NumParams && !FTI.isVariadic &&
+ !LangOpts.requiresStrictPrototypes() && !LangOpts.OpenCL) {
// Simple void foo(), where the incoming T is the result type.
T = Context.getFunctionNoProtoType(T, EI);
} else {
@@ -5290,8 +5293,10 @@
S.Diag(FTI.Params[0].IdentLoc,
diag::err_ident_list_in_fn_declaration);
D.setInvalidType(true);
- // Recover by creating a K&R-style function type.
- T = Context.getFunctionNoProtoType(T, EI);
+ // Recover by creating a K&R-style function type, if possible.
+ T = (!LangOpts.requiresStrictPrototypes() && !LangOpts.OpenCL)
+ ? Context.getFunctionNoProtoType(T, EI)
+ : Context.IntTy;
break;
}
Index: clang/lib/Sema/SemaDecl.cpp
===================================================================
--- clang/lib/Sema/SemaDecl.cpp
+++ clang/lib/Sema/SemaDecl.cpp
@@ -8818,6 +8818,9 @@
(D.getDeclSpec().isTypeRep() &&
D.getDeclSpec().getRepAsType().get()->isFunctionProtoType()) ||
(!R->getAsAdjusted<FunctionType>() && R->isFunctionProtoType());
+ assert(
+ (HasPrototype || !SemaRef.getLangOpts().requiresStrictPrototypes()) &&
+ "Strict prototypes are required");
NewFD = FunctionDecl::Create(
SemaRef.Context, DC, D.getBeginLoc(), NameInfo, R, TInfo, SC,
Index: clang/lib/Parse/ParseDecl.cpp
===================================================================
--- clang/lib/Parse/ParseDecl.cpp
+++ clang/lib/Parse/ParseDecl.cpp
@@ -6661,8 +6661,11 @@
else if (RequiresArg)
Diag(Tok, diag::err_argument_required_after_attribute);
- HasProto = ParamInfo.size() || getLangOpts().CPlusPlus
- || getLangOpts().OpenCL;
+ // OpenCL disallows functions without a prototype, but it doesn't enforce
+ // strict prototypes as in C2x because it allows a function definition to
+ // have an identifier list.
+ HasProto = ParamInfo.size() || getLangOpts().requiresStrictPrototypes() ||
+ getLangOpts().OpenCL;
// If we have the closing ')', eat it.
Tracker.consumeClose();
@@ -6799,7 +6802,7 @@
/// Note that identifier-lists are only allowed for normal declarators, not for
/// abstract-declarators.
bool Parser::isFunctionDeclaratorIdentifierList() {
- return !getLangOpts().CPlusPlus
+ return !getLangOpts().requiresStrictPrototypes()
&& Tok.is(tok::identifier)
&& !TryAltiVecVectorToken()
// K&R identifier lists can't have typedefs as identifiers, per C99
@@ -6833,6 +6836,10 @@
void Parser::ParseFunctionDeclaratorIdentifierList(
Declarator &D,
SmallVectorImpl<DeclaratorChunk::ParamInfo> &ParamInfo) {
+ // We should never reach this point in C2x or C++.
+ assert(!getLangOpts().requiresStrictPrototypes() &&
+ "Cannot parse an identifier list in C2x or C++");
+
// If there was no identifier specified for the declarator, either we are in
// an abstract-declarator, or we are in a parameter declarator which was found
// to be abstract. In abstract-declarators, identifier lists are not valid:
Index: clang/lib/AST/ASTContext.cpp
===================================================================
--- clang/lib/AST/ASTContext.cpp
+++ clang/lib/AST/ASTContext.cpp
@@ -4239,6 +4239,13 @@
QualType
ASTContext::getFunctionNoProtoType(QualType ResultTy,
const FunctionType::ExtInfo &Info) const {
+ // FIXME: This assertion cannot be enabled (yet) because the ObjC rewriter
+ // functionality creates a function without a prototype regardless of
+ // language mode (so it makes them even in C++). Once the rewriter has been
+ // fixed, this assertion can be enabled again.
+ //assert(!LangOpts.requiresStrictPrototypes() &&
+ // "strict prototypes are disabled");
+
// Unique functions, to guarantee there is only one function of a particular
// structure.
llvm::FoldingSetNodeID ID;
@@ -11235,7 +11242,7 @@
// We really shouldn't be making a no-proto type here.
- if (ArgTypes.empty() && Variadic && !getLangOpts().CPlusPlus)
+ if (ArgTypes.empty() && Variadic && !getLangOpts().requiresStrictPrototypes())
return getFunctionNoProtoType(ResType, EI);
FunctionProtoType::ExtProtoInfo EPI;
Index: clang/include/clang/Driver/Options.td
===================================================================
--- clang/include/clang/Driver/Options.td
+++ clang/include/clang/Driver/Options.td
@@ -2294,6 +2294,11 @@
def fretain_comments_from_system_headers : Flag<["-"], "fretain-comments-from-system-headers">, Group<f_Group>, Flags<[CC1Option]>,
MarshallingInfoFlag<LangOpts<"RetainCommentsFromSystemHeaders">>;
+def fstrict_prototypes : Flag<["-"], "fstrict-prototypes">, Group<f_Group>,
+ MarshallingInfoFlag<LangOpts<"StrictPrototypesExt">>,
+ HelpText<"Function declarations without a parameter list behave as though the parameter list were 'void'">,
+ Flags<[CC1Option, CoreOption]>;
+
def fmudflapth : Flag<["-"], "fmudflapth">, Group<f_Group>;
def fmudflap : Flag<["-"], "fmudflap">, Group<f_Group>;
def fnested_functions : Flag<["-"], "fnested-functions">, Group<f_Group>;
Index: clang/include/clang/Basic/LangOptions.h
===================================================================
--- clang/include/clang/Basic/LangOptions.h
+++ clang/include/clang/Basic/LangOptions.h
@@ -521,6 +521,12 @@
/// as a string.
std::string getOpenCLVersionString() const;
+ /// Returns true if functions without prototypes or functions with an
+ /// identifier list (aka K&R C functions) are not allowed.
+ bool requiresStrictPrototypes() const {
+ return CPlusPlus || C2x || StrictPrototypesExt;
+ }
+
/// Check if return address signing is enabled.
bool hasSignReturnAddress() const {
return getSignReturnAddressScope() != SignReturnAddressScopeKind::None;
Index: clang/include/clang/Basic/LangOptions.def
===================================================================
--- clang/include/clang/Basic/LangOptions.def
+++ clang/include/clang/Basic/LangOptions.def
@@ -121,6 +121,7 @@
LANGOPT(GNUKeywords , 1, 1, "GNU keywords")
VALUE_LANGOPT(GNUCVersion , 32, 0, "GNU C compatibility version")
BENIGN_LANGOPT(ImplicitInt, 1, 0, "C89 implicit 'int'")
+LANGOPT(StrictPrototypesExt, 1, 0, "require function types to have a prototype")
LANGOPT(Digraphs , 1, 0, "digraphs")
BENIGN_LANGOPT(HexFloats , 1, 0, "C99 hexadecimal float constants")
LANGOPT(CXXOperatorNames , 1, 0, "C++ operator name keywords")
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -172,6 +172,11 @@
New Compiler Flags
------------------
+- Added the ``-fstrict-prototypes`` flag to allow users to opt into the C2x
+ behavior where a function with an empty parameter list is treated as though
+ the parameter list were ``void``. There is no ``-fno-strict-prototypes``
+ flag; this feature cannot be disabled in language modes where it is required,
+ such as C++ or C2x.
Deprecated Compiler Flags
-------------------------
@@ -232,6 +237,8 @@
- Implemented the `*_WIDTH` macros to complete support for
`WG14 N2412 Two's complement sign representation for C2x <https://www9.open-std.org/jtc1/sc22/wg14/www/docs/n2412.pdf>`_.
- Implemented `WG14 N2418 Adding the u8 character prefix <http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2418.pdf>`_.
+- Implemented `WG14 N2841 No function declarators without prototypes <https://www9.open-std.org/jtc1/sc22/wg14/www/docs/n2841.htm>`_
+ and `WG14 N2432 Remove support for function definitions with identifier lists <https://www9.open-std.org/jtc1/sc22/wg14/www/docs/n2432.pdf>`_.
C++ Language Changes in Clang
-----------------------------
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