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In C++23, discarded statements and if consteval statements can nest
arbitrarily. To support that, we
keep track of whether the parent of the current evaluation context
is discarded or immediate.
This is done at the construction of an evaluation context
to improve performance.
Fixes https://bugs.llvm.org/show_bug.cgi?id=52231
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D113749
Files:
clang/include/clang/Sema/Sema.h
clang/lib/Sema/SemaExpr.cpp
clang/lib/Sema/SemaStmt.cpp
clang/test/SemaCXX/cxx2b-consteval-if.cpp
Index: clang/test/SemaCXX/cxx2b-consteval-if.cpp
===================================================================
--- clang/test/SemaCXX/cxx2b-consteval-if.cpp
+++ clang/test/SemaCXX/cxx2b-consteval-if.cpp
@@ -52,6 +52,5 @@
return 0;
}
}
- // FIXME: this error should not happen.
- return 0.0; // expected-error {{'auto' in return type deduced as 'double' here but deduced as 'int' in earlier return statement}}
+ return 0.0;
}
Index: clang/lib/Sema/SemaStmt.cpp
===================================================================
--- clang/lib/Sema/SemaStmt.cpp
+++ clang/lib/Sema/SemaStmt.cpp
@@ -3563,8 +3563,7 @@
bool HasDeducedReturnType =
CurLambda && hasDeducedReturnType(CurLambda->CallOperator);
- if (ExprEvalContexts.back().Context ==
- ExpressionEvaluationContext::DiscardedStatement &&
+ if (ExprEvalContexts.back().isDiscardedStatementContext() &&
(HasDeducedReturnType || CurCap->HasImplicitReturnType)) {
if (RetValExp) {
ExprResult ER =
@@ -3880,8 +3879,7 @@
if (RetVal.isInvalid())
return StmtError();
StmtResult R = BuildReturnStmt(ReturnLoc, RetVal.get());
- if (R.isInvalid() || ExprEvalContexts.back().Context ==
- ExpressionEvaluationContext::DiscardedStatement)
+ if (R.isInvalid() || ExprEvalContexts.back().isDiscardedStatementContext())
return R;
if (VarDecl *VD =
@@ -3966,8 +3964,7 @@
// C++1z: discarded return statements are not considered when deducing a
// return type.
- if (ExprEvalContexts.back().Context ==
- ExpressionEvaluationContext::DiscardedStatement &&
+ if (ExprEvalContexts.back().isDiscardedStatementContext() &&
FnRetType->getContainedAutoType()) {
if (RetValExp) {
ExprResult ER =
Index: clang/lib/Sema/SemaExpr.cpp
===================================================================
--- clang/lib/Sema/SemaExpr.cpp
+++ clang/lib/Sema/SemaExpr.cpp
@@ -16567,6 +16567,17 @@
ExpressionEvaluationContextRecord::ExpressionKind ExprContext) {
ExprEvalContexts.emplace_back(NewContext, ExprCleanupObjects.size(), Cleanup,
LambdaContextDecl, ExprContext);
+
+ // Discarded statements and immediate contexts nested in other
+ // Discarded statements or immediate context are themselves
+ // discarded statements or immediate context respectively.
+ ExprEvalContexts.back().InDiscardedStatement =
+ ExprEvalContexts[ExprEvalContexts.size() - 2]
+ .isDiscardedStatementContext();
+ ExprEvalContexts.back().InImmediateFunctionContext =
+ ExprEvalContexts[ExprEvalContexts.size() - 2]
+ .isImmediateFunctionContext();
+
Cleanup.reset();
if (!MaybeODRUseExprs.empty())
std::swap(MaybeODRUseExprs, ExprEvalContexts.back().SavedMaybeODRUseExprs);
@@ -18956,6 +18967,10 @@
/// during overload resolution or within sizeof/alignof/typeof/typeid.
bool Sema::DiagRuntimeBehavior(SourceLocation Loc, ArrayRef<const Stmt*> Stmts,
const PartialDiagnostic &PD) {
+
+ if (ExprEvalContexts.back().isDiscardedStatementContext())
+ return false;
+
switch (ExprEvalContexts.back().Context) {
case ExpressionEvaluationContext::Unevaluated:
case ExpressionEvaluationContext::UnevaluatedList:
Index: clang/include/clang/Sema/Sema.h
===================================================================
--- clang/include/clang/Sema/Sema.h
+++ clang/include/clang/Sema/Sema.h
@@ -1297,6 +1297,9 @@
EK_Decltype, EK_TemplateArgument, EK_Other
} ExprContext;
+ bool InDiscardedStatement : 1;
+ bool InImmediateFunctionContext : 1;
+
ExpressionEvaluationContextRecord(ExpressionEvaluationContext Context,
unsigned NumCleanupObjects,
CleanupInfo ParentCleanup,
@@ -1304,7 +1307,8 @@
ExpressionKind ExprContext)
: Context(Context), ParentCleanup(ParentCleanup),
NumCleanupObjects(NumCleanupObjects), NumTypos(0),
- ManglingContextDecl(ManglingContextDecl), ExprContext(ExprContext) {}
+ ManglingContextDecl(ManglingContextDecl), ExprContext(ExprContext),
+ InDiscardedStatement(false), InImmediateFunctionContext(false) {}
bool isUnevaluated() const {
return Context == ExpressionEvaluationContext::Unevaluated ||
@@ -1318,7 +1322,13 @@
}
bool isImmediateFunctionContext() const {
- return Context == ExpressionEvaluationContext::ImmediateFunctionContext;
+ return Context == ExpressionEvaluationContext::ImmediateFunctionContext ||
+ InImmediateFunctionContext;
+ }
+
+ bool isDiscardedStatementContext() const {
+ return Context == ExpressionEvaluationContext::DiscardedStatement ||
+ InDiscardedStatement;
}
};
@@ -9140,14 +9150,7 @@
bool isImmediateFunctionContext() const {
assert(!ExprEvalContexts.empty() &&
"Must be in an expression evaluation context");
- for (const ExpressionEvaluationContextRecord &context :
- llvm::reverse(ExprEvalContexts)) {
- if (context.isImmediateFunctionContext())
- return true;
- if (context.isUnevaluated())
- return false;
- }
- return false;
+ return ExprEvalContexts.back().isImmediateFunctionContext();
}
/// RAII class used to determine whether SFINAE has
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