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Mark the lambda function pointer conversion operator as noexcept. 

This implements CWG DR 1722 and fixes PR40309. Patch by Ignat Loskutov.

llvm-svn: 351750
This commit is contained in:
Aaron Ballman 2019-01-21 16:25:08 +00:00
parent f9694fdbbc
commit a2b04ad5c4
5 changed files with 30 additions and 9 deletions
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3
clang/lib/Sema/SemaLambda.cpp
View File

@ -1227,9 +1227,10 @@ static void addFunctionPointerConversion(Sema &S,
FunctionProtoType::ExtProtoInfo ConvExtInfo(
S.Context.getDefaultCallingConvention(
/*IsVariadic=*/false, /*IsCXXMethod=*/true));
// The conversion function is always const.
// The conversion function is always const and noexcept.
ConvExtInfo.TypeQuals = Qualifiers();
ConvExtInfo.TypeQuals.addConst();
ConvExtInfo.ExceptionSpec.Type = EST_BasicNoexcept;
QualType ConvTy =
S.Context.getFunctionType(PtrToFunctionTy, None, ConvExtInfo);

14
clang/test/AST/ast-dump-expr.cpp
View File

@ -290,7 +290,7 @@ void PrimaryExpressions(Ts... a) {
// CHECK-NEXT: Destructor
// CHECK-NEXT: CXXMethodDecl 0x{{[^ ]*}} <col:6, col:8> col:3 operator() 'auto () const' inline
// CHECK-NEXT: CompoundStmt
// CHECK-NEXT: CXXConversionDecl 0x{{[^ ]*}} <col:3, col:8> col:3 implicit constexpr operator auto (*)() 'auto (*() const)()' inline
// CHECK-NEXT: CXXConversionDecl 0x{{[^ ]*}} <col:3, col:8> col:3 implicit constexpr operator auto (*)() 'auto (*() const noexcept)()' inline
// CHECK-NEXT: CXXMethodDecl 0x{{[^ ]*}} <col:3, col:8> col:3 implicit __invoke 'auto ()' static inline
// CHECK-NEXT: CompoundStmt 0x{{[^ ]*}} <col:7, col:8>
@ -307,7 +307,7 @@ void PrimaryExpressions(Ts... a) {
// CHECK-NEXT: CXXMethodDecl 0x{{[^ ]*}} <col:16, col:18> col:3 operator() 'auto (int, ...) const' inline
// CHECK-NEXT: ParmVarDecl 0x{{[^ ]*}} <col:6, col:10> col:10 a 'int'
// CHECK-NEXT: CompoundStmt
// CHECK-NEXT: CXXConversionDecl 0x{{[^ ]*}} <col:3, col:18> col:3 implicit constexpr operator auto (*)(int, ...) 'auto (*() const)(int, ...)' inline
// CHECK-NEXT: CXXConversionDecl 0x{{[^ ]*}} <col:3, col:18> col:3 implicit constexpr operator auto (*)(int, ...) 'auto (*() const noexcept)(int, ...)' inline
// CHECK-NEXT: CXXMethodDecl 0x{{[^ ]*}} <col:3, col:18> col:3 implicit __invoke 'auto (int, ...)' static inline
// CHECK-NEXT: ParmVarDecl 0x{{[^ ]*}} <col:6, col:10> col:10 a 'int'
// CHECK-NEXT: CompoundStmt 0x{{[^ ]*}} <col:17, col:18>
@ -455,7 +455,7 @@ void PrimaryExpressions(Ts... a) {
// CHECK-NEXT: Destructor
// CHECK-NEXT: CXXMethodDecl 0x{{[^ ]*}} <col:8, col:19> col:3 constexpr operator() 'auto () const' inline
// CHECK-NEXT: CompoundStmt
// CHECK-NEXT: CXXConversionDecl 0x{{[^ ]*}} <col:3, col:19> col:3 implicit constexpr operator auto (*)() 'auto (*() const)()' inline
// CHECK-NEXT: CXXConversionDecl 0x{{[^ ]*}} <col:3, col:19> col:3 implicit constexpr operator auto (*)() 'auto (*() const noexcept)()' inline
// CHECK-NEXT: CXXMethodDecl 0x{{[^ ]*}} <col:3, col:19> col:3 implicit __invoke 'auto ()' static inline
// CHECK-NEXT: CompoundStmt 0x{{[^ ]*}} <col:18, col:19>
@ -471,7 +471,7 @@ void PrimaryExpressions(Ts... a) {
// CHECK-NEXT: Destructor
// CHECK-NEXT: CXXMethodDecl 0x{{[^ ]*}} <col:8, col:17> col:3 operator() 'auto ()' inline
// CHECK-NEXT: CompoundStmt
// CHECK-NEXT: CXXConversionDecl 0x{{[^ ]*}} <col:3, col:17> col:3 implicit constexpr operator auto (*)() 'auto (*() const)()' inline
// CHECK-NEXT: CXXConversionDecl 0x{{[^ ]*}} <col:3, col:17> col:3 implicit constexpr operator auto (*)() 'auto (*() const noexcept)()' inline
// CHECK-NEXT: CXXMethodDecl 0x{{[^ ]*}} <col:3, col:17> col:3 implicit __invoke 'auto ()' static inline
// CHECK-NEXT: CompoundStmt 0x{{[^ ]*}} <col:16, col:17>
@ -487,7 +487,7 @@ void PrimaryExpressions(Ts... a) {
// CHECK-NEXT: Destructor
// CHECK-NEXT: CXXMethodDecl 0x{{[^ ]*}} <col:8, col:18> col:3 operator() 'auto () const noexcept' inline
// CHECK-NEXT: CompoundStmt
// CHECK-NEXT: CXXConversionDecl 0x{{[^ ]*}} <col:3, col:18> col:3 implicit constexpr operator auto (*)() noexcept 'auto (*() const)() noexcept' inline
// CHECK-NEXT: CXXConversionDecl 0x{{[^ ]*}} <col:3, col:18> col:3 implicit constexpr operator auto (*)() noexcept 'auto (*() const noexcept)() noexcept' inline
// CHECK-NEXT: CXXMethodDecl 0x{{[^ ]*}} <col:3, col:18> col:3 implicit __invoke 'auto () noexcept' static inline
// CHECK-NEXT: CompoundStmt 0x{{[^ ]*}} <col:17, col:18>
@ -505,7 +505,7 @@ void PrimaryExpressions(Ts... a) {
// CHECK-NEXT: CompoundStmt
// CHECK-NEXT: ReturnStmt 0x{{[^ ]*}} <col:17, col:24>
// CHECK-NEXT: IntegerLiteral 0x{{[^ ]*}} <col:24> 'int' 0
// CHECK-NEXT: CXXConversionDecl 0x{{[^ ]*}} <col:3, col:27> col:3 implicit constexpr operator int (*)() 'auto (*() const)() -> int' inline
// CHECK-NEXT: CXXConversionDecl 0x{{[^ ]*}} <col:3, col:27> col:3 implicit constexpr operator int (*)() 'auto (*() const noexcept)() -> int' inline
// CHECK-NEXT: CXXMethodDecl 0x{{[^ ]*}} <col:3, col:27> col:3 implicit __invoke 'auto () -> int' static inline
// CHECK-NEXT: CompoundStmt 0x{{[^ ]*}} <col:15, col:27>
// CHECK-NEXT: ReturnStmt 0x{{[^ ]*}} <col:17, col:24>
@ -568,4 +568,4 @@ void NonADLCall3() {
// CHECK: CallExpr 0x{{[^ ]*}} <line:[[@LINE+1]]:{{[^>]+}}> 'void'{{$}}
f(x);
}
} // namespace test_adl_call_three
} // namespace test_adl_call_three

12
clang/test/CXX/drs/dr17xx.cpp
View File

@ -76,3 +76,15 @@ namespace dr1758 { // dr1758: 3.7
A a{b};
#endif
}
namespace dr1722 { // dr1722: 9.0
#if __cplusplus >= 201103L
void f() {
const auto lambda = [](int x) { return x + 1; };
// Without the DR applied, this static_assert would fail.
static_assert(
noexcept((int (*)(int))(lambda)),
"Lambda-to-function-pointer conversion is expected to be noexcept");
}
#endif
} // namespace dr1722

8
clang/test/CXX/expr/expr.prim/expr.prim.lambda/p9.cpp Normal file
View File

@ -0,0 +1,8 @@
// RUN: %clang_cc1 -fsyntax-only -std=c++17 %s -verify
// expected-no-diagnostics
void test_noexcept() {
const auto lambda = [](int x) { return x + 1; };
static_assert(noexcept((int (*)(int))(lambda)),
"Lambda-to-function-pointer conversion is expected to be noexcept");
}

2
clang/www/cxx_dr_status.html
View File

@ -10147,7 +10147,7 @@ and <I>POD class</I></td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#1722">1722</a></td>
<td>CD4</td>
<td>Should lambda to function pointer conversion function be <TT>noexcept</TT>?</td>
<td class="none" align="center">Unknown</td>
<td class="full" align="center">Clang 9.0</td>
</tr>
<tr class="open" id="1723">
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#1723">1723</a></td>