We deferred the evaluation of dependent immediate invocations in https://reviews.llvm.org/D119375 until instantiation.
We should also not consider them referenced from a non-consteval context.
Fixes: https://github.com/llvm/llvm-project/issues/55601
```
template<typename T>
class Bar {
consteval static T x() { return 5; }
public:
Bar() : a(x()) {}
private:
int a;
};
Bar<int> g();
```
Is now accepted by clang. Previously it errored with: `cannot take address of consteval function 'x' outside of an immediate invocation Bar() : a(x()) {}`
Differential Revision: https://reviews.llvm.org/D132031
The restrictions added in D131704 were not sufficient to avoid all non-constant
expression contexts. In particular constant initialization cases.
We need to check EvaluatingDecl to detect if the variable we are initializing is
constexpr or not.
At this point it looks like this is the remaining case affecting various projects
with this diagnostic.
Differential Revision: https://reviews.llvm.org/D131874
Followup patch for D128083
Previously, using a non-consteval constructor from an consteval constructor would code generates the consteval constructor.
Example
```
template <typename T>
struct S {
T i;
consteval S() = default;
};
struct Foo {
Foo() {}
};
void func() {
S<Foo> three; // incorrectly accepted by clang.
}
```
This happened because clang erroneously disregards `consteval` specifier for a `consteval explicitly defaulted special member functions in a class template` if it has dependent data members without a `consteval default constructor`.
According to
```
C++14 [dcl.constexpr]p6 (CWG DR647/CWG DR1358):
If the instantiated template specialization of a constexpr function
template or member function of a class template would fail to satisfy
the requirements for a constexpr function or constexpr constructor, that
specialization is still a constexpr function or constexpr constructor,
even though a call to such a function cannot appear in a constant
expression.
```
Therefore the `consteval defaulted constructor of a class template` should be considered `consteval` even if the data members' default constructors are not consteval.
Keeping this constructor `consteval` allows complaining while processing the call to data member constructors.
(Same applies for other special member functions).
This works fine even when we have more than one default constructors since we process the constructors after the templates are instantiated.
This does not address initialization issues raised in
[2602](https://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#2602) and compiler divergence seen in https://godbolt.org/z/va9EMvvMe
Fixes: https://github.com/llvm/llvm-project/issues/51593
Differential Revision: https://reviews.llvm.org/D131479
We should not mark a function as "referenced" if we call it within a
ConstantExpr, because the expression will be folded to a value in LLVM
IR. To prevent emitting consteval function declarations, we should not "jump
over" a ConstantExpr when it is a top-level ParmVarDecl's subexpression.
Fixes https://github.com/llvm/llvm-project/issues/48230
Reviewed By: erichkeane, aaron.ballman, ChuanqiXu
Differenitial Revision: https://reviews.llvm.org/D119646
Previously, we would instantiate the UDL by marking the function as
referenced and potentially binding to a temporary; this skipped
transforming the call when the UDL was dependent on a template
parameter.
Now, we defer all the work to instantiating the call expression for the
UDL. This ensures that constant evaluation occurs at compile time
rather than deferring until runtime.
Fixes Issue 54578.
Full-expressions are Sema-generated implicit nodes that cover
constant-expressions and expressions-with-cleanup for temporaries.
Ignore those as part of implicit-ignore, and also remove too-aggressive
IgnoreImplicit (which includes nested ImplicitCastExprs, for example)
on unpacked sub-expressions.
Add some unittests to demonstrate that RecursiveASTVisitor sees through
ConstantExpr nodes correctly.
Adjust cxx2a-consteval test to cover diagnostics for nested consteval
expressions that were previously missed.
Fixes bug #53044.
We were not creating an evaluation context for the TU scope, so we
never popped an evaluation context for it. Popping the evaluation
context triggers a number of diagnostics, including warnings about
immediate invocations that we were previously missing.
Note: I think we have an additional issue that we should solve, but not
as part of this patch. I don't think Clang is properly modeling static
initialization as happening before constant expression evaluation. I
think structure members members are zero initialized per
http://eel.is/c++draft/basic.start.static#1,
https://eel.is/c++draft/basic.start.static#2.sentence-2, and
http://eel.is/c++draft/dcl.init#general-6.2 and the new test case
actually should be accepted. However, it's also worth noting that other
compilers behave the way this patch makes Clang behave:
https://godbolt.org/z/T7noqhdPr
Value-dependent ConstantExprs are not meant to be evaluated.
There is an assert in Expr::EvaluateAsConstantExpr that ensures this condition.
But before this patch the method was called without prior check.
Fixes https://github.com/llvm/llvm-project/issues/52768
Reviewed By: erichkeane
Differential Revision: https://reviews.llvm.org/D119375
When reaching the end of a function body, we need to ensure that the
ExitFunctionBodyRAII object is destroyed before we pop the declaration context
for the function. Exiting the function body causes us to handle immediate
invocations, which involves template transformations that need to know the
correct type for this.
This addresses PR48235.
It seems that Clang 11 regressed functionality that was working in
Clang 10 regarding calling a few overloaded operators in an immediate
context. Specifically, we were not checking for immediate invocations
of array subscripting and the arrow operators, but we properly handle
the other overloaded operators.
This fixes the two problematic operators and adds some test coverage to
show they're equivalent to calling the operator directly.
This addresses PR50779.
callee in constant evaluation.
We previously made a deep copy of function parameters of class type when
passing them, resulting in the destructor for the parameter applying to
the original argument value, ignoring any modifications made in the
function body. This also meant that the 'this' pointer of the function
parameter could be observed changing between the caller and the callee.
This change completely reimplements how we model function parameters
during constant evaluation. We now model them roughly as if they were
variables living in the caller, albeit with an artificially reduced
scope that covers only the duration of the function call, instead of
modeling them as temporaries in the caller that we partially "reparent"
into the callee at the point of the call. This brings some minor
diagnostic improvements, as well as significantly reduced stack usage
during constant evaluation.
callee in constant evaluation.
We previously made a deep copy of function parameters of class type when
passing them, resulting in the destructor for the parameter applying to
the original argument value, ignoring any modifications made in the
function body. This also meant that the 'this' pointer of the function
parameter could be observed changing between the caller and the callee.
This change completely reimplements how we model function parameters
during constant evaluation. We now model them roughly as if they were
variables living in the caller, albeit with an artificially reduced
scope that covers only the duration of the function call, instead of
modeling them as temporaries in the caller that we partially "reparent"
into the callee at the point of the call. This brings some minor
diagnostic improvements, as well as significantly reduced stack usage
during constant evaluation.
callee in constant evaluation.
We previously made a deep copy of function parameters of class type when
passing them, resulting in the destructor for the parameter applying to
the original argument value, ignoring any modifications made in the
function body. This also meant that the 'this' pointer of the function
parameter could be observed changing between the caller and the callee.
This change completely reimplements how we model function parameters
during constant evaluation. We now model them roughly as if they were
variables living in the caller, albeit with an artificially reduced
scope that covers only the duration of the function call, instead of
modeling them as temporaries in the caller that we partially "reparent"
into the callee at the point of the call. This brings some minor
diagnostic improvements, as well as significantly reduced stack usage
during constant evaluation.
Prevent IR-gen from emitting consteval declarations
Summary: with this patch instead of emitting calls to consteval function. the IR-gen will emit a store of the already computed result.
Summary: with this patch instead of emitting calls to consteval function. the IR-gen will emit a store of the already computed result.
Reviewers: rsmith
Reviewed By: rsmith
Subscribers: cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D76420
Summary:
Changes:
- handle immediate invocations for constructors.
- add tests
after this patch i believe the implementation of consteval is nearly standard compliant, but IR-gen still needs to be taught not to emit consteval declarations.
Reviewers: rsmith
Reviewed By: rsmith
Subscribers: wchilders
Differential Revision: https://reviews.llvm.org/D74007
function and an overridden function until we know whether the overriding
function is deleted.
We previously did these checks when we first built the declaration,
which was too soon in some cases. We now defer all these checks to the
end of the class.
Also add missing check that a consteval function cannot override a
non-consteval function and vice versa.
Summary:
Changes:
- Calls to consteval function are now evaluated in constant context but IR is still generated for them.
- Add diagnostic for taking address of a consteval function in non-constexpr context.
- Add diagnostic for address of consteval function accessible at runtime.
- Add tests
Reviewers: rsmith, aaron.ballman
Reviewed By: rsmith
Subscribers: mgrang, riccibruno, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D63960
appropriate during constant evaluation.
Note that the evaluator is sometimes invoked on incomplete expressions.
In such cases, if an object is constructed but we never reach the point
where it would be destroyed (and it has non-trivial destruction), we
treat the expression as having an unmodeled side-effect.
llvm-svn: 372538
Summary:
this revision adds Lexing, Parsing and Basic Semantic for the consteval specifier as specified by http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1073r3.html
with this patch, the consteval specifier is treated as constexpr but can only be applied to function declaration.
Changes:
- add the consteval keyword.
- add parsing of consteval specifier for normal declarations and lambdas expressions.
- add the whether a declaration is constexpr is now represented by and enum everywhere except for variable because they can't be consteval.
- adapt diagnostic about constexpr to print constexpr or consteval depending on the case.
- add tests for basic semantic.
Reviewers: rsmith, martong, shafik
Reviewed By: rsmith
Subscribers: eraman, efriedma, rnkovacs, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D61790
llvm-svn: 363362
Utkarsh Saxena