Previously, we didin't build a DeclRefExpr which refers to an invalid declaration.
In this patch, we handle this case by building an empty RecoveryExpr,
which will preserve more broken code (AST parent nodes that contain the
RecoveryExpr is preserved in the AST).
Differential Revision: https://reviews.llvm.org/D120812
This improves diagnostic (& important to me, DWARF) accuracy - otherwise
there could be ambiguities between "std::nullptr_t" and some user-defined
type that's /actually/ "nullptr_t" defined in the global namespace.
Differential Revision: https://reviews.llvm.org/D110044
Before this patch, CXXCtorInitializers that don't typecheck get discarded in
most cases. In particular:
- typos that can't be corrected don't turn into RecoveryExpr. The full expr
disappears instead, and without an init expr we discard the node.
- initializers that fail initialization (e.g. constructor overload resolution)
are discarded too.
This patch addresses both these issues (a bit clunkily and repetitively, for
member/base/delegating initializers)
It does not preserve any AST nodes when the member/base can't be resolved or
other problems of that nature. That breaks invariants of CXXCtorInitializer
itself, and we don't have a "weak" RecoveryCtorInitializer like we do for Expr.
I believe the changes to diagnostics in existing tests are improvements.
(We're able to do some analysis on the non-broken parts of the initializer)
Differential Revision: https://reviews.llvm.org/D101641
Because of typo-correction, the AST can be transformed, and the transformed
AST is marginally useful for diagnostics purpose, the following
diagnostics usually do harm than good (easily cause confusions).
Given the following code:
```
void abcc();
void test() {
if (abc());
// diagnostic 1 (for the typo-correction): the typo is correct to `abcc()`, so the code is treate as `if (abcc())` in AST perspective;
// diagnostic 2 (for mismatch type): we perform an type-analysis on `if`, discover the type is not match
}
```
The secondary diagnostic "convertable to bool" is likely bogus to users.
The idea is to use RecoveryExpr (clang's dependent mechanism) to preserve the
recovery behavior but suppress all follow-up diagnostics.
Differential Revision: https://reviews.llvm.org/D89946
RecoveryExpr was always lvalue, but it is wrong if we use it to model
broken function calls, function call expression has more compliated rules:
- a call to a function whose return type is an lvalue reference yields an lvalue;
- a call to a function whose return type is an rvalue reference yields an xvalue;
- a call to a function whose return type is nonreference type yields a prvalue;
This patch makes the recovery-expr align with the function call if it is
modeled a broken call.
Differential revision: https://reviews.llvm.org/D83201
Summary:
For a none-function-like unresolved expression, clang builds a TypoExpr
for it, and tries to correct it afterwards. If the typo-correction
fails, clang just drops the whole expr.
This patch improves the recovery strategy -- if the typo-correction
fails, we preserve the AST by degrading the typo exprs to recovery
exprs.
This would improve toolings for "undef_var" broken cases:
```
void foo();
void test() {
fo^o(undef_var); // go-to-def, hover still works.
}
```
TESTED=ran tests with this patch + turn-on-recovery-ast patch, it breaks
one declare_variant_messages testcase (the diagnostics are slightly
changed), I think it is acceptable.
```
Error: 'error' diagnostics seen but not expected:
File llvm-project/clang/test/OpenMP/declare_variant_messages.cpp Line 16: expected 'match' clause on 'omp declare variant' directive
File llvm-project/clang/test/OpenMP/declare_variant_messages.cpp Line 57: expected 'match' clause on 'omp declare variant' directive
error: 'warning' diagnostics expected but not seen:
File llvm-project/clang/test/OpenMP/declare_variant_messages.cpp Line 47: the context selector 'kind' in the context set 'device' cannot have a score ('<invalid>'); score ignored
File llvm-project/clang/test/OpenMP/declare_variant_messages.cpp Line 87: the context selector 'kind' in the context set 'device' cannot have a score ('<invalid>'); score ignored
error: 'warning' diagnostics seen but not expected:
File llvm-project/clang/test/OpenMP/declare_variant_messages.cpp Line 47: the context selector 'kind' in the context set 'device' cannot have a score ('<recovery-expr>()'); score ignored
File llvm-project/clang/test/OpenMP/declare_variant_messages.cpp Line 87: the context selector 'kind' in the context set 'device' cannot have a score ('<recovery-expr>()'); score ignored
6 errors generated.
```
Reviewers: sammccall, jdoerfert
Subscribers: sstefan1, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D80733
Summary:
The Initializer of a InitListExpr can be reset to null, which leads to
nullptr-acces crashes.
Reviewers: sammccall
Subscribers: cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D80980
Summary:
With recovery-ast, we will get an undeduced `auto` return type for
"auto foo()->undef()" function declaration, the function decl still keeps
valid, it is dangerous, and breaks assumptions in clang, and leads crashes.
This patch invalidates these functions, if we deduce autos from the
return rexpression, which is similar to auto VarDecl.
Subscribers: cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D80221
RecoveryExprs are modeled as dependent type to prevent bogus diagnostics
and crashes in clang.
This patch allows to preseve the type for broken calls when the
RecoveryEprs have a known type, e.g. a broken non-overloaded call, a
overloaded call when the all candidates have the same return type, so
that more features (code completion still work on "take2args(x).^") still
work.
However, adding the type is risky, which may result in more clang code being
affected leading to new crashes and hurt diagnostic, and it requires large
effort to minimize the affect (update all sites in clang to handle errorDepend
case), so we add a new flag (off by default) to allow us to develop/test
them incrementally.
This patch also has some trivial fixes to suppress diagnostics (to prevent regressions).
Tested:
all existing tests are passed (when both "-frecovery-ast", "-frecovery-ast-type" flags are flipped on);
Reviewed By: sammccall
Subscribers: rsmith, arphaman, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D79160
Summary:
This patch contains 2 separate changes:
1) the initializer of a variable should play no part in decl "invalid" bit;
2) preserve the invalid initializer via recovery exprs;
With 1), we will regress the diagnostics (one big regression is that we loose
the "selected 'begin' function with iterator type" diagnostic in for-range stmt;
but with 2) together, we don't have regressions (the new diagnostics seems to be
improved).
Reviewers: sammccall
Reviewed By: sammccall
Subscribers: cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D78116
Summary: Previously, we dropped the AST node for nonexistent member exprs.
Reviewers: sammccall
Subscribers: cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D76764
Normally clang avoids creating expressions when it encounters semantic
errors, even if the parser knows which expression to produce.
This works well for the compiler. However, this is not ideal for
source-level tools that have to deal with broken code, e.g. clangd is
not able to provide navigation features even for names that compiler
knows how to resolve.
The new RecoveryExpr aims to capture the minimal set of information
useful for the tools that need to deal with incorrect code:
source range of the expression being dropped,
subexpressions of the expression.
We aim to make constructing RecoveryExprs as simple as possible to
ensure writing code to avoid dropping expressions is easy.
Producing RecoveryExprs can result in new code paths being taken in the
frontend. In particular, clang can produce some new diagnostics now and
we aim to suppress bogus ones based on Expr::containsErrors.
We deliberately produce RecoveryExprs only in the parser for now to
minimize the code affected by this patch. Producing RecoveryExprs in
Sema potentially allows to preserve more information (e.g. type of an
expression), but also results in more code being affected. E.g.
SFINAE checks will have to take presence of RecoveryExprs into account.
Initial implementation only works in C++ mode, as it relies on compiler
postponing diagnostics on dependent expressions. C and ObjC often do not
do this, so they require more work to make sure we do not produce too
many bogus diagnostics on the new expressions.
See documentation of RecoveryExpr for more details.
original patch from Ilya
This change is based on https://reviews.llvm.org/D61722
Reviewers: sammccall, rsmith
Reviewed By: sammccall, rsmith
Tags: #clang
Differential Revision: https://reviews.llvm.org/D69330
Haojian Wu