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* If constant evaluation fails due to an unspecified pointer comparison,Richard Smith2019-12-161-15/+15
| | | | | produce a note saying that rather than the default "evaluation failed" note.
* For P0784R7: add support for explicit destructor calls andRichard Smith2019-09-271-1/+1
| | | | | | pseudo-destructor calls in constant evaluation. llvm-svn: 373122
* For P0784R7: Add support for dynamic allocation with new / delete duringRichard Smith2019-09-271-16/+17
| | | | | | constant evaluation. llvm-svn: 373036
* [c++20] Implement semantic restrictions for C++20 designatedRichard Smith2019-08-301-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | initializers. This has some interesting interactions with our existing extensions to support C99 designated initializers as an extension in C++. Those are resolved as follows: * We continue to permit the full breadth of C99 designated initializers in C++, with the exception that we disallow a partial overwrite of an initializer with a non-trivially-destructible type. (Full overwrite is OK, because we won't run the first initializer at all.) * The C99 extensions are disallowed in SFINAE contexts and during overload resolution, where they could change the meaning of valid programs. * C++20 disallows reordering of initializers. We only check for that for the simple cases that the C++20 rules permit (designators of the form '.field_name =' and continue to allow reordering in other cases). It would be nice to improve this behavior in future. * All C99 designated initializer extensions produce a warning by default in C++20 mode. People are going to learn the C++ rules based on what Clang diagnoses, so it's important we diagnose these properly by default. * In C++ <= 17, we apply the C++20 rules rather than the C99 rules, and so still diagnose C99 extensions as described above. We continue to accept designated C++20-compatible initializers in C++ <= 17 silently by default (but naturally still reject under -pedantic-errors). This is not a complete implementation of P0329R4. In particular, that paper introduces new non-C99-compatible syntax { .field { init } }, and we do not support that yet. This is based on a previous patch by Don Hinton, though I've made substantial changes when addressing the above interactions. Differential Revision: https://reviews.llvm.org/D59754 llvm-svn: 370544
* Treat the range of representable values of floating-point types as [-inf, ↵Richard Smith2019-07-061-7/+21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +inf] not as [-max, +max]. Summary: Prior to r329065, we used [-max, max] as the range of representable values because LLVM's `fptrunc` did not guarantee defined behavior when truncating from a larger floating-point type to a smaller one. Now that has been fixed, we can make clang follow normal IEEE 754 semantics in this regard and take the larger range [-inf, +inf] as the range of representable values. In practice, this affects two parts of the frontend: * the constant evaluator no longer treats floating-point evaluations that result in +-inf as being undefined (because they no longer leave the range of representable values of the type) * UBSan no longer treats conversions to floating-point type that are outside the [-max, +max] range as being undefined In passing, also remove the float-divide-by-zero sanitizer from -fsanitize=undefined, on the basis that while it's undefined per C++ rules (and we disallow it in constant expressions for that reason), it is defined by Clang / LLVM / IEEE 754. Reviewers: rnk, BillyONeal Subscribers: cfe-commits Tags: #clang Differential Revision: https://reviews.llvm.org/D63793 llvm-svn: 365272
* Reject attempts to call non-static member functions on objects outsideRichard Smith2019-05-121-2/+2
| | | | | | | | | | | | | | | | their lifetime in constant expressions. This is undefined behavior per [class.cdtor]p2. We continue to allow this for objects whose values are not visible within the constant evaluation, because there's no way we can tell whether the access is defined or not, existing code relies on the ability to make such calls, and every other compiler allows such calls. This reinstates r360499, reverted in r360531. llvm-svn: 360538
* Revert rL360499 and rL360464 from cfe/trunk:Simon Pilgrim2019-05-111-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | Reject attempts to call non-static member functions on objects outside their lifetime in constant expressions. This is undefined behavior per [class.cdtor]p2. We continue to allow this for objects whose values are not visible within the constant evaluation, because there's no way we can tell whether the access is defined or not, existing code relies on the ability to make such calls, and every other compiler allows such calls. ........ Fix handling of objects under construction during constant expression evaluation. It's not enough to just track the LValueBase that we're evaluating, we need to also track the path to the objects whose constructors are running. ........ Fixes windows buildbots llvm-svn: 360531
* Reject attempts to call non-static member functions on objects outsideRichard Smith2019-05-111-2/+2
| | | | | | | | | | | | | | their lifetime in constant expressions. This is undefined behavior per [class.cdtor]p2. We continue to allow this for objects whose values are not visible within the constant evaluation, because there's no way we can tell whether the access is defined or not, existing code relies on the ability to make such calls, and every other compiler allows such calls. llvm-svn: 360499
* Don't warn about runtime behavior problems in variable initializers that weRichard Smith2017-09-231-7/+7
| | | | | | | | know are going to be constant-evaluated. Any relevant diagnostics should be produced by constant expression evaluation. llvm-svn: 314067
* DR616, and part of P0135R1: member access (or pointer-to-member access) on aRichard Smith2016-12-031-3/+3
| | | | | | | temporary produces an xvalue, not a prvalue. Support this by materializing the temporary prior to performing the member access. llvm-svn: 288563
* DR583, DR1512: Implement a rewrite to C++'s 'composite pointer type' rules.Richard Smith2016-10-211-9/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | This has two significant effects: 1) Direct relational comparisons between null pointer constants (0 and nullopt) and pointers are now ill-formed. This was always the case for C, and it appears that C++ only ever permitted by accident. For instance, cases like nullptr < &a are now rejected. 2) Comparisons and conditional operators between differently-cv-qualified pointer types now work, and produce a composite type that both source pointer types can convert to (when possible). For instance, comparison between 'int **' and 'const int **' is now valid, and uses an intermediate type of 'const int *const *'. Clang previously supported #2 as an extension. We do not accept the cases in #1 as an extension. I've tested a fair amount of code to check that this doesn't break it, but if it turns out that someone is relying on this, we can easily add it back as an extension. This is a re-commit of r284800. llvm-svn: 284890
* Revert "DR583, DR1512: Implement a rewrite to C++'s 'composite pointer type' ↵Renato Golin2016-10-211-9/+9
| | | | | | | | rules." This reverts commit r284800, as it failed all ARM/AArch64 bots. llvm-svn: 284811
* DR583, DR1512: Implement a rewrite to C++'s 'composite pointer type' rules.Richard Smith2016-10-211-9/+9
| | | | | | | | | | | | | | | | | | | | | | | | This has two significant effects: 1) Direct relational comparisons between null pointer constants (0 and nullopt) and pointers are now ill-formed. This was always the case for C, and it appears that C++ only ever permitted by accident. For instance, cases like nullptr < &a are now rejected. 2) Comparisons and conditional operators between differently-cv-qualified pointer types now work, and produce a composite type that both source pointer types can convert to (when possible). For instance, comparison between 'int **' and 'const int **' is now valid, and uses an intermediate type of 'const int *const *'. Clang previously supported #2 as an extension. We do not accept the cases in #1 as an extension. I've tested a fair amount of code to check that this doesn't break it, but if it turns out that someone is relying on this, we can easily add it back as an extension. llvm-svn: 284800
* Improve -Wconstant-conversionRichard Trieu2016-01-291-2/+2
| | | | | | | | | | | | | | Switch the evaluation from isIntegerConstantExpr to EvaluateAsInt. EvaluateAsInt will evaluate more types of expressions than isIntegerConstantExpr. Move one case from -Wsign-conversion to -Wconstant-conversion. The case is: 1) Source and target types are signed 2) Source type is wider than the target type 3) The source constant value is positive 4) The conversion will store the value as negative in the target. llvm-svn: 259271
* PR17381: Treat undefined behavior during expression evaluation as an unmodeledRichard Smith2015-12-031-2/+2
| | | | | | | | | | | | | | | | | | | | | side-effect, so that we don't allow speculative evaluation of such expressions during code generation. This caused a diagnostic quality regression, so fix constant expression diagnostics to prefer either the first "can't be constant folded" diagnostic or the first "not a constant expression" diagnostic depending on the kind of evaluation we're doing. This was always the intent, but didn't quite work correctly before. This results in certain initializers that used to be constant initializers to no longer be; in particular, things like: float f = 1e100; are no longer accepted in C. This seems appropriate, as such constructs would lead to code being executed if sanitizers are enabled. llvm-svn: 254574
* [Sema] Warn when shifting a negative value.Davide Italiano2015-07-061-1/+1
| | | | | | | | | | | | | | | Example: % ./clang -Wshift-negative-value emit.c emit.c:3:14: warning: shifting a negative signed value is undefined [-Wshift-negative-value] int a = -1 << 3; ~~ ^ 1 warning generated. PR: 24026 Differential Revision: http://reviews.llvm.org/D10938 Reviewed by: rsmith llvm-svn: 241478
* [c++1z] Most of N4268 (allow constant evaluation for non-type template ↵Richard Smith2014-11-261-3/+3
| | | | | | | | | arguments). We don't yet support pointer-to-member template arguments that have undergone pointer-to-member conversions, mostly because we don't have a mangling for them yet. llvm-svn: 222807
* PR21180: Lambda closure types are neither aggregates nor literal types.Richard Smith2014-10-071-1/+1
| | | | llvm-svn: 219222
* PR19346: Adding 0 to a null pointer has defined behavior in C++. Allow it in ↵Richard Smith2014-04-081-1/+3
| | | | | | constant expressions. llvm-svn: 205757
* Creating a printing policy for "half":Yunzhong Gao2014-03-181-1/+1
| | | | | | | | | | | | Since "half" is an OpenCL keyword and clang accepts __fp16 as an extension for other languages, error messages and metadata (and hence debug info) should refer to the half-precision floating point as "__fp16" instead of "half" when compiling for non-OpenCL languages. This patch creates a new printing policy for half in a similar manner to what is done for bool and wchar_t. Differential Revision: http://llvm-reviews.chandlerc.com/D2952 llvm-svn: 204164
* Sema: Do not allow lambda expressions to appear inside of constant expressionsDavid Majnemer2013-10-251-3/+1
| | | | | | | | | We would previously not diagnose this which would lead to crashes (on very strange code). This fixes PR17675. llvm-svn: 193397
* Fix handling of const_cast from prvalue to rvalue reference: such a cast isRichard Smith2013-06-141-1/+1
| | | | | | | only permitted if the source object is of class type, and should materialize a temporary for the reference to bind to. llvm-svn: 184017
* Refactor constant expression evaluation to associate the complete object of aRichard Smith2013-06-031-2/+4
| | | | | | | | | | | | | | materialized temporary with the corresponding MaterializeTemporaryExpr. This is groundwork for providing C++11's guaranteed static initialization for global references bound to lifetime-extended temporaries (if the initialization is a constant expression). In passing, fix a couple of bugs where some evaluation failures didn't trigger diagnostics, and a rejects-valid where potential constant expression testing would assume that it knew the dynamic type of *this and would reject programs which relied on it being some derived type. llvm-svn: 183093
* The 'constexpr implies const' rule for non-static member functions is gone inRichard Smith2013-04-211-4/+4
| | | | | | | | | C++1y, so stop adding the 'const' there. Provide a compatibility warning for code relying on this in C++11, with a fix-it hint. Update our lazily-written tests to add the const, except for those ones which were testing our implementation of this rule. llvm-svn: 179969
* Don't crash while printing APValues that are lvalues casted to aDouglas Gregor2013-01-291-0/+13
| | | | | | decidedly non-reference, non-pointer type. Fixes <rdar://problem/13090123>. llvm-svn: 173747
* Don't treat overflow in floating-point conversions as a hard error in ↵Eli Friedman2012-07-171-3/+3
| | | | | | constant evaluation. <rdar://problem/11874571>. llvm-svn: 160394
* Ensure that we instantiate static reference data members of class templatesRichard Smith2012-03-021-2/+2
| | | | | | | | | early, since their values can be used in constant expressions in C++11. For odr-use checking, the opposite change is required, since references are odr-used whether or not they satisfy the requirements for appearing in a constant expression. llvm-svn: 151881
* Implement DR1454. This allows all intermediate results in constant expressionsRichard Smith2012-02-151-14/+12
| | | | | | | | | | | | to be core constant expressions (including pointers and references to temporaries), and makes constexpr calculations Turing-complete. A Turing machine simulator is included as a testcase. This opens up the possibilty of removing CCValue entirely, and removing some copies from the constant evaluator in the process, but that cleanup is not part of this change. llvm-svn: 150557
* Update constexpr implementation to match CWG's chosen approach for core issuesRichard Smith2012-02-131-7/+12
| | | | | | | | | | | | | | | | | | | | 1358, 1360, 1452 and 1453. - Instantiations of constexpr functions are always constexpr. This removes the need for separate declaration/definition checking, which is now gone. - This makes it possible for a constexpr function to be virtual, if they are only dependently virtual. Virtual calls to such functions are not constant expressions. - Likewise, it's now possible for a literal type to have virtual base classes. A constexpr constructor for such a type cannot actually produce a constant expression, though, so add a special-case diagnostic for a constructor call to such a type rather than trying to evaluate it. - Classes with trivial default constructors (for which value initialization can produce a fully-initialized value) are considered literal types. - Classes with volatile members are not literal types. - constexpr constructors can be members of non-literal types. We do not yet use static initialization for global objects constructed in this way. llvm-svn: 150359
* Update to new resolution for DR1458. When taking the address of an object ofRichard Smith2012-02-101-3/+4
| | | | | | | incomplete class type which has an overloaded operator&, it's now just unspecified whether the overloaded operator or the builtin is used. llvm-svn: 150234
* Implement DR1458: Taking the address of an object of incomplete class type isRichard Smith2012-02-081-0/+16
| | | | | | | not a constant expression, because we can't tell whether the complete class type will have an overloaded operator&. llvm-svn: 150066
* Implement the agreed resolution to DR1457: a signed left shift of a 1 bit intoRichard Smith2012-02-081-2/+5
| | | | | | | | | | the sign bit doesn't have undefined behavior, but a signed left shift of a 1 bit out of the sign bit still does. As promised to Howard :) The suppression of the potential constant expression checking in system headers is also removed, since the problem it was working around is gone. llvm-svn: 150059
* constexpr: Fix implementation of DR1311: check for volatile qualifiers inRichard Smith2012-02-051-9/+8
| | | | | | | lvalue-to-rvalue conversions on the source type of the conversion, not the target type (which has them removed for non-class types). llvm-svn: 149796
* In C++11 mode, when an integral constant expression is desired and we have aRichard Smith2012-02-041-13/+15
| | | | | | | | | | | | | | | | | | value of class type, look for a unique conversion operator converting to integral or unscoped enumeration type and use that. Implements [expr.const]p5. Sema::VerifyIntegerConstantExpression now performs the conversion and returns the converted result. Some important callers of Expr::isIntegralConstantExpr have been switched over to using it (including all of those required for C++11 conformance); this switch brings a side-benefit of improved diagnostics and, in several cases, simpler code. However, some language extensions and attributes have not been moved across and will not perform implicit conversions on constant expressions of literal class type where an ICE is required. In passing, fix static_assert to perform a contextual conversion to bool on its argument. llvm-svn: 149776
* constexpr:Richard Smith2012-02-021-9/+59
| | | | | | | * support the gcc __builtin_constant_p() ? ... : ... folding hack in C++11 * check for unspecified values in pointer comparisons and pointer subtractions llvm-svn: 149578
* constexpr: check for overflow in pointer subtraction.Richard Smith2012-02-011-1/+9
| | | | | | | | | | | | | This is a mess. According to the C++11 standard, pointer subtraction only has undefined behavior if the difference of the array indices does not fit into a ptrdiff_t. However, common implementations effectively perform a char* subtraction first, and then divide the result by the element size, which can cause overflows in some cases. Those cases are not considered to be undefined behavior by this change; perhaps they should be. llvm-svn: 149490
* constexpr: overflow checking for integral and floating-point arithmetic.Richard Smith2012-02-011-0/+41
| | | | llvm-svn: 149473
* constexpr: require 'this' to point to an object in a constexpr method call.Richard Smith2012-02-011-0/+9
| | | | llvm-svn: 149467
* constexpr: Treat INT_MIN % -1 as undefined behavior in C++11. Technically, itRichard Smith2012-01-311-0/+1
| | | | | | isn't, but this is just a (reported) defect in the wording. llvm-svn: 149448
* constexpr: the result of a relational operator between pointers to void isRichard Smith2012-01-311-1/+12
| | | | | | | unspecified unless the pointers are equal; therefore, such a comparison is not a constant expression unless the pointers are equal. llvm-svn: 149366
* constexpr: catch a collection of integral undefined behaviors:Richard Smith2012-01-311-0/+24
| | | | | | | | | -INT_MIN and INT_MIN / -1 Shift by a negative or too large quantity Left shift of negative value Overflow in left shift llvm-svn: 149344
* constexpr: remove integral conversion overflow checking introduced in r149286.Richard Smith2012-01-311-2/+2
| | | | | | | As Eli points out, this is implementation-defined, and the way we define it makes this fine. llvm-svn: 149327
* constexpr: disallow signed integer overflow in integral conversions in constantRichard Smith2012-01-301-0/+3
| | | | | | expressions in C++11. llvm-svn: 149286
* constexpr: converted constant expression handling for enumerator values, caseRichard Smith2012-01-181-2/+5
| | | | | | | | | | values and non-type template arguments of integral and enumeration types. This change causes some legal C++98 code to no longer compile in C++11 mode, by enforcing the C++11 rule that narrowing integral conversions are not permitted in the final implicit conversion sequence for the above cases. llvm-svn: 148439
* Pedantic diagnostic correction: in C++, we have integral constant expressions,Richard Smith2012-01-151-1/+1
| | | | | | | | not integer constant expressions. In passing, fix the 'folding is an extension' diagnostic to not claim we're accepting the code, since that's not true in -pedantic-errors mode, and add this diagnostic to -Wgnu. llvm-svn: 148209
* Allow constant-folding of references which were formed in a manner not permittedRichard Smith2012-01-121-1/+2
| | | | | | in a constant expression, for compatibility with g++. llvm-svn: 148020
* C++11 generalized constant expressions: implement checking and diagnostics forRichard Smith2012-01-061-0/+21
| | | | | | | pointer-arithmetic-related undefined behavior and unspecified results. We continue to fold such values, but now notice they aren't constant expressions. llvm-svn: 147659
* Unrevert r147271, reverted in r147361.Richard Smith2011-12-301-2/+2
| | | | | | | | | | | | Also temporarily remove the assumption from IR gen that we can emit IR for every constant we can fold, since it isn't currently true in C++11, to fix PR11676. Original comment from r147271: constexpr: perform zero-initialization prior to / instead of performing a constructor call when appropriate. Thanks to Eli for spotting this. llvm-svn: 147384
* Revert r147271. This fixes PR11676.Rafael Espindola2011-12-301-2/+2
| | | | llvm-svn: 147362
* constexpr: support for evaluation and codegen of typeid constants.Richard Smith2011-12-271-3/+2
| | | | llvm-svn: 147290
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