RIscRIpt updated this revision to Diff 464522.
RIscRIpt retitled this revision from "[AST] Add C++11 attribute
msvc::constexpr" to "Add C++11 attribute msvc::constexpr".
RIscRIpt added a comment.
Add more tests, don't alter constexprKind of `[[msvc::constexpr]]` functions -
instead change implementation of `isConstexpr`
In D134475#3827712 <https://reviews.llvm.org/D134475#3827712>, @aaron.ballman
wrote:
> ... we're missing some significant test coverage for it. I had some
> suggestions for specific things we should be thinking about, but another
> useful test would be to modify an existing constexpr test to add a RUN line
> enabling ms extensions, and use a macro to switch between `constexpr` and
> `[[msvc::constexpr]]` based on those RUN lines. Basically, ensure that
> `[[msvc::constexpr]]` gives the same behavior (both in terms of evaluation
> and in terms of semantic checking) as `constexpr`. WDYT?
That's a good idea. Based on my experiments with MSVC, I am more convinced that
`constexpr` and `[[msvc::constexpr]]` are synonyms (with some extra
undocumented (yet?) features by MSFT). I added more tests as per your
suggestion.
Regarding existing tests, I was able to find only
`clang/test/AST/Interp/functions.cpp` which uses `constexpr` only with
functions (otherwise `-Dconstexpr=[[msvc::constexpr]]` would break code in case
there are `constexpr` variables) - I added `RUN` lines there.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D134475/new/
https://reviews.llvm.org/D134475
Files:
clang/include/clang/AST/Decl.h
clang/include/clang/Basic/Attr.td
clang/include/clang/Basic/AttrDocs.td
clang/include/clang/Basic/DiagnosticSemaKinds.td
clang/lib/AST/Decl.cpp
clang/lib/Sema/SemaDeclAttr.cpp
clang/test/AST/Interp/functions.cpp
clang/test/AST/msvc-attrs-invalid.cpp
clang/test/AST/msvc-attrs.cpp
clang/test/Misc/pragma-attribute-supported-attributes-list.test
Index: clang/test/Misc/pragma-attribute-supported-attributes-list.test
===================================================================
--- clang/test/Misc/pragma-attribute-supported-attributes-list.test
+++ clang/test/Misc/pragma-attribute-supported-attributes-list.test
@@ -83,6 +83,7 @@
// CHECK-NEXT: LoaderUninitialized (SubjectMatchRule_variable_is_global)
// CHECK-NEXT: Lockable (SubjectMatchRule_record)
// CHECK-NEXT: MIGServerRoutine (SubjectMatchRule_function, SubjectMatchRule_objc_method, SubjectMatchRule_block)
+// CHECK-NEXT: MSConstexpr (SubjectMatchRule_function)
// CHECK-NEXT: MSStruct (SubjectMatchRule_record)
// CHECK-NEXT: MaybeUndef (SubjectMatchRule_variable_is_parameter)
// CHECK-NEXT: MicroMips (SubjectMatchRule_function)
Index: clang/test/AST/msvc-attrs.cpp
===================================================================
--- /dev/null
+++ clang/test/AST/msvc-attrs.cpp
@@ -0,0 +1,35 @@
+// RUN: %clang_cc1 -fms-extensions -std=c++20 -ast-dump %s | FileCheck %s
+// RUN: not %clang_cc1 -Werror=ignored-attributes -ast-dump %s 2> %t.stderr.txt
+// RUN: FileCheck -check-prefix CHECK-DIAG-NO-MSX %s < %t.stderr.txt
+
+// CHECK: msvc-attrs.cpp:[[@LINE+3]]:21, col:32> col:26 f0 'void ()'
+// CHECK: MSConstexprAttr 0x{{[0-9a-f]+}} <col:3, col:9>
+// CHECK-DIAG-NO-MSX: msvc-attrs.cpp:[[@LINE+1]]:3: error: 'constexpr' attribute ignored
+[[msvc::constexpr]] void f0() {}
+
+struct s0 {
+ // CHECK: CXXConstructorDecl 0x{{[0-9a-f]+}} <line:[[@LINE+2]]:23, col:29> col:23 s0 'void ()' implicit-inline
+ // CHECK: MSConstexprAttr 0x{{[0-9a-f]+}} <col:5, col:11>
+ [[msvc::constexpr]] s0() {}
+
+ // CHECK: CXXDestructorDecl 0x{{[0-9a-f]+}} <line:[[@LINE+2]]:23, col:30> col:23 ~s0 'void () noexcept' implicit-inline
+ // CHECK: MSConstexprAttr 0x{{[0-9a-f]+}} <col:5, col:11>
+ [[msvc::constexpr]] ~s0() {}
+
+ // CHECK: CXXMethodDecl 0x{{[0-9a-f]+}} <line:[[@LINE+2]]:23, col:42> col:36 used f1 'void ()' virtual implicit-inline
+ // CHECK: MSConstexprAttr 0x{{[0-9a-f]+}} <col:5, col:11>
+ [[msvc::constexpr]] virtual void f1() {}
+};
+
+// Check 'constexpr' and '[[msvc::constexpr]]' functions can call each other
+void f2();
+constexpr void f3();
+
+[[msvc::constexpr]] void f2() { f3(); }
+constexpr void f3() { f2(); }
+
+[[msvc::constexpr]] void f4();
+constexpr void f5();
+
+void f4() { f5(); }
+constexpr void f5() { f4(); }
Index: clang/test/AST/msvc-attrs-invalid.cpp
===================================================================
--- /dev/null
+++ clang/test/AST/msvc-attrs-invalid.cpp
@@ -0,0 +1,14 @@
+// RUN: not %clang_cc1 -fms-extensions -std=c++20 -ast-dump %s 2> %t.stderr.txt
+// RUN: FileCheck %s < %t.stderr.txt
+
+void runtime() {}
+
+// CHECK: msvc-attrs-invalid.cpp:[[@LINE+1]]:26: error: constexpr function never produces a constant expression [-Winvalid-constexpr]
+[[msvc::constexpr]] void f0() { runtime(); }
+
+// CHECK: msvc-attrs-invalid.cpp:[[@LINE+1]]:3: error: {{\[\[}}msvc::constexpr{{]]}} cannot be applied to a 'constexpr' or 'consteval' function 'f1'
+[[msvc::constexpr]] constexpr void f1() {}
+
+// CHECK: msvc-attrs-invalid.cpp:[[@LINE+1]]:3: error: {{\[\[}}msvc::constexpr{{]]}} cannot be applied to a 'constexpr' or 'consteval' function 'f2'
+[[msvc::constexpr]] consteval void f2() {}
+
Index: clang/test/AST/Interp/functions.cpp
===================================================================
--- clang/test/AST/Interp/functions.cpp
+++ clang/test/AST/Interp/functions.cpp
@@ -1,5 +1,7 @@
// RUN: %clang_cc1 -fexperimental-new-constant-interpreter -verify %s
// RUN: %clang_cc1 -verify=ref %s
+// RUN: %clang_cc1 -fexperimental-new-constant-interpreter -fms-extensions -verify -Dconstexpr=[[msvc::constexpr]] %s
+// RUN: %clang_cc1 -fms-extensions -verify=ref -Dconstexpr=[[msvc::constexpr]] %s
// expected-no-diagnostics
// ref-no-diagnostics
Index: clang/lib/Sema/SemaDeclAttr.cpp
===================================================================
--- clang/lib/Sema/SemaDeclAttr.cpp
+++ clang/lib/Sema/SemaDeclAttr.cpp
@@ -7050,6 +7050,15 @@
D->addAttr(::new (S.Context) ThreadAttr(S.Context, AL));
}
+static void handleMSConstexprAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
+ auto *FD = cast<FunctionDecl>(D);
+ if (FD->isConstexprSpecified() || FD->isConsteval()) {
+ S.Diag(AL.getLoc(), diag::err_ms_constexpr_not_distinct) << FD;
+ return;
+ }
+ D->addAttr(::new (S.Context) MSConstexprAttr(S.Context, AL));
+}
+
static void handleAbiTagAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
SmallVector<StringRef, 4> Tags;
for (unsigned I = 0, E = AL.getNumArgs(); I != E; ++I) {
@@ -8987,6 +8996,9 @@
case ParsedAttr::AT_Thread:
handleDeclspecThreadAttr(S, D, AL);
break;
+ case ParsedAttr::AT_MSConstexpr:
+ handleMSConstexprAttr(S, D, AL);
+ break;
// HLSL attributes:
case ParsedAttr::AT_HLSLNumThreads:
Index: clang/lib/AST/Decl.cpp
===================================================================
--- clang/lib/AST/Decl.cpp
+++ clang/lib/AST/Decl.cpp
@@ -3121,6 +3121,10 @@
Parent->markedVirtualFunctionPure();
}
+bool FunctionDecl::isConstexpr() const {
+ return getConstexprKind() != ConstexprSpecKind::Unspecified || hasAttr<MSConstexprAttr>();
+}
+
template<std::size_t Len>
static bool isNamed(const NamedDecl *ND, const char (&Str)[Len]) {
IdentifierInfo *II = ND->getIdentifier();
Index: clang/include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -2777,6 +2777,8 @@
InGroup<CXXPre14Compat>, DefaultIgnore;
def note_constexpr_body_previous_return : Note<
"previous return statement is here">;
+def err_ms_constexpr_not_distinct : Error<
+ "[[msvc::constexpr]] cannot be applied to a 'constexpr' or 'consteval' function %0">;
// C++20 function try blocks in constexpr
def ext_constexpr_function_try_block_cxx20 : ExtWarn<
Index: clang/include/clang/Basic/AttrDocs.td
===================================================================
--- clang/include/clang/Basic/AttrDocs.td
+++ clang/include/clang/Basic/AttrDocs.td
@@ -3478,6 +3478,14 @@
}];
}
+def MSConstexprDocs : Documentation {
+ let Category = DocCatStmt;
+ let Content = [{
+This attribute is an alias of ``constexpr`` for functions.
+Available only as Microsoft extension (``-fms-extensions``).
+ }];
+}
+
def MSNoVTableDocs : Documentation {
let Category = DocCatDecl;
let Content = [{
Index: clang/include/clang/Basic/Attr.td
===================================================================
--- clang/include/clang/Basic/Attr.td
+++ clang/include/clang/Basic/Attr.td
@@ -3500,6 +3500,13 @@
// Microsoft-related attributes
+def MSConstexpr : InheritableAttr {
+ let LangOpts = [MicrosoftExt];
+ let Spellings = [CXX11<"msvc", "constexpr">];
+ let Subjects = SubjectList<[Function]>;
+ let Documentation = [MSConstexprDocs];
+}
+
def MSNoVTable : InheritableAttr, TargetSpecificAttr<TargetMicrosoftCXXABI> {
let Spellings = [Declspec<"novtable">];
let Subjects = SubjectList<[CXXRecord]>;
Index: clang/include/clang/AST/Decl.h
===================================================================
--- clang/include/clang/AST/Decl.h
+++ clang/include/clang/AST/Decl.h
@@ -2312,9 +2312,7 @@
}
/// Whether this is a (C++11) constexpr function or constexpr constructor.
- bool isConstexpr() const {
- return getConstexprKind() != ConstexprSpecKind::Unspecified;
- }
+ bool isConstexpr() const;
void setConstexprKind(ConstexprSpecKind CSK) {
FunctionDeclBits.ConstexprKind = static_cast<uint64_t>(CSK);
}
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