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[AST][RecoveryExpr] Build RecoveryExpr for "undef_var" cases. 

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
This commit is contained in:
Haojian Wu 2020-05-28 13:43:35 +02:00
parent 85117e286d
commit 21ccc684ff
2 changed files with 34 additions and 2 deletions
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17
clang/lib/Sema/SemaExprCXX.cpp
View File

@ -8304,8 +8304,21 @@ ExprResult Sema::ActOnFinishFullExpr(Expr *FE, SourceLocation CC,
}
FullExpr = CorrectDelayedTyposInExpr(FullExpr.get());
if (FullExpr.isInvalid())
return ExprError();
if (FullExpr.isInvalid()) {
// Typo-correction fails, we rebuild the broken AST with the typos degraded
// to RecoveryExpr.
// FIXME: we lose source locations for RecoveryExpr, as TypoExpr doesn't
// track source locations.
struct TyposReplace : TreeTransform<TyposReplace> {
TyposReplace(Sema &SemaRef) : TreeTransform(SemaRef) {}
ExprResult TransformTypoExpr(TypoExpr *E) {
return this->SemaRef.CreateRecoveryExpr(E->getBeginLoc(),
E->getEndLoc(), {});
}
} TT(*this);
return TT.TransformExpr(FE);
}
CheckCompletedExpr(FullExpr.get(), CC, IsConstexpr);

19
clang/test/AST/ast-dump-recovery.cpp
View File

@ -10,6 +10,25 @@ int some_func(int *);
// CHECK-NEXT: `-IntegerLiteral {{.*}} 123
// DISABLED-NOT: -RecoveryExpr {{.*}} contains-errors
int invalid_call = some_func(123);
void test_invalid_call(int s) {
// CHECK: CallExpr {{.*}} '<dependent type>' contains-errors
// CHECK-NEXT: |-UnresolvedLookupExpr {{.*}} 'some_func'
// CHECK-NEXT: |-RecoveryExpr {{.*}} <<invalid sloc>>
// CHECK-NEXT: `-BinaryOperator {{.*}} <<invalid sloc>, col:28>
// CHECK-NEXT: |-RecoveryExpr {{.*}} <<invalid sloc>>
// CHECK-NEXT: `-IntegerLiteral {{.*}} <col:28> 'int' 1
some_func(undef1, undef2+1);
// CHECK: BinaryOperator {{.*}} '<dependent type>' contains-errors '='
// CHECK-NEXT: |-DeclRefExpr {{.*}} 's'
// CHECK-NEXT: `-CallExpr {{.*}} '<dependent type>' contains-errors
// CHECK-NEXT: |-UnresolvedLookupExpr {{.*}} 'some_func'
// CHECK-NEXT: `-RecoveryExpr {{.*}} contains-errors
s = some_func(undef1);
// CHECK: `-VarDecl {{.*}} invalid var 'int'
// FIXME: preserve the broken call.
int var = some_func(undef1);
}
int ambig_func(double);
int ambig_func(float);