[clang] 59a5c1f - [clang][Sema] Diagnose exceptions only in non-dependent context in discarded `try/catch/throw` blocks (#139859)
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Wed May 28 07:10:58 PDT 2025
Author: Rajveer Singh Bharadwaj
Date: 2025-05-28T07:10:55-07:00
New Revision: 59a5c1f25f578bb1a4951a4610b4e683ee94a870
URL: https://github.com/llvm/llvm-project/commit/59a5c1f25f578bb1a4951a4610b4e683ee94a870
DIFF: https://github.com/llvm/llvm-project/commit/59a5c1f25f578bb1a4951a4610b4e683ee94a870.diff
LOG: [clang][Sema] Diagnose exceptions only in non-dependent context in discarded `try/catch/throw` blocks (#139859)
Resolves #138939
When enabling `--fno-exceptions` flag, discarded statements containing
`try/catch/throw` in an independent context can be avoided from being
rejected.
Added:
Modified:
clang/include/clang/Sema/Sema.h
clang/lib/Sema/SemaExprCXX.cpp
clang/lib/Sema/SemaStmt.cpp
clang/lib/Sema/TreeTransform.h
clang/test/SemaCXX/no-exceptions.cpp
Removed:
################################################################################
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index b423e2a61fef9..6ce9ae588b637 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -11170,6 +11170,8 @@ class Sema final : public SemaBase {
StmtResult ActOnCXXTryBlock(SourceLocation TryLoc, Stmt *TryBlock,
ArrayRef<Stmt *> Handlers);
+ void DiagnoseExceptionUse(SourceLocation Loc, bool IsTry);
+
StmtResult ActOnSEHTryBlock(bool IsCXXTry, // try (true) or __try (false) ?
SourceLocation TryLoc, Stmt *TryBlock,
Stmt *Handler);
diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
index d8338e08dd0f7..7b08fb869ccca 100644
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -848,13 +848,8 @@ ExprResult Sema::BuildCXXThrow(SourceLocation OpLoc, Expr *Ex,
const llvm::Triple &T = Context.getTargetInfo().getTriple();
const bool IsOpenMPGPUTarget =
getLangOpts().OpenMPIsTargetDevice && (T.isNVPTX() || T.isAMDGCN());
- // Don't report an error if 'throw' is used in system headers or in an OpenMP
- // target region compiled for a GPU architecture.
- if (!IsOpenMPGPUTarget && !getLangOpts().CXXExceptions &&
- !getSourceManager().isInSystemHeader(OpLoc) && !getLangOpts().CUDA) {
- // Delay error emission for the OpenMP device code.
- targetDiag(OpLoc, diag::err_exceptions_disabled) << "throw";
- }
+
+ DiagnoseExceptionUse(OpLoc, /* IsTry= */ false);
// In OpenMP target regions, we replace 'throw' with a trap on GPU targets.
if (IsOpenMPGPUTarget)
diff --git a/clang/lib/Sema/SemaStmt.cpp b/clang/lib/Sema/SemaStmt.cpp
index 1fc96664dd87c..bc873937f6dc5 100644
--- a/clang/lib/Sema/SemaStmt.cpp
+++ b/clang/lib/Sema/SemaStmt.cpp
@@ -4311,13 +4311,8 @@ StmtResult Sema::ActOnCXXTryBlock(SourceLocation TryLoc, Stmt *TryBlock,
const llvm::Triple &T = Context.getTargetInfo().getTriple();
const bool IsOpenMPGPUTarget =
getLangOpts().OpenMPIsTargetDevice && (T.isNVPTX() || T.isAMDGCN());
- // Don't report an error if 'try' is used in system headers or in an OpenMP
- // target region compiled for a GPU architecture.
- if (!IsOpenMPGPUTarget && !getLangOpts().CXXExceptions &&
- !getSourceManager().isInSystemHeader(TryLoc) && !getLangOpts().CUDA) {
- // Delay error emission for the OpenMP device code.
- targetDiag(TryLoc, diag::err_exceptions_disabled) << "try";
- }
+
+ DiagnoseExceptionUse(TryLoc, /* IsTry= */ true);
// In OpenMP target regions, we assume that catch is never reached on GPU
// targets.
@@ -4419,6 +4414,23 @@ StmtResult Sema::ActOnCXXTryBlock(SourceLocation TryLoc, Stmt *TryBlock,
Handlers);
}
+void Sema::DiagnoseExceptionUse(SourceLocation Loc, bool IsTry) {
+ const llvm::Triple &T = Context.getTargetInfo().getTriple();
+ const bool IsOpenMPGPUTarget =
+ getLangOpts().OpenMPIsTargetDevice && (T.isNVPTX() || T.isAMDGCN());
+
+ // Don't report an error if 'try' is used in system headers or in an OpenMP
+ // target region compiled for a GPU architecture.
+ if (IsOpenMPGPUTarget || getLangOpts().CUDA)
+ // Delay error emission for the OpenMP device code.
+ return;
+
+ if (!getLangOpts().CXXExceptions &&
+ !getSourceManager().isInSystemHeader(Loc) &&
+ !CurContext->isDependentContext())
+ targetDiag(Loc, diag::err_exceptions_disabled) << (IsTry ? "try" : "throw");
+}
+
StmtResult Sema::ActOnSEHTryBlock(bool IsCXXTry, SourceLocation TryLoc,
Stmt *TryBlock, Stmt *Handler) {
assert(TryBlock && Handler);
diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index 7629e84f5b848..bd839087c66ed 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -9169,6 +9169,8 @@ StmtResult TreeTransform<Derived>::TransformCXXTryStmt(CXXTryStmt *S) {
Handlers.push_back(Handler.getAs<Stmt>());
}
+ getSema().DiagnoseExceptionUse(S->getTryLoc(), /* IsTry= */ true);
+
if (!getDerived().AlwaysRebuild() && TryBlock.get() == S->getTryBlock() &&
!HandlerChanged)
return S;
@@ -14391,6 +14393,8 @@ TreeTransform<Derived>::TransformCXXThrowExpr(CXXThrowExpr *E) {
if (SubExpr.isInvalid())
return ExprError();
+ getSema().DiagnoseExceptionUse(E->getThrowLoc(), /* IsTry= */ false);
+
if (!getDerived().AlwaysRebuild() &&
SubExpr.get() == E->getSubExpr())
return E;
diff --git a/clang/test/SemaCXX/no-exceptions.cpp b/clang/test/SemaCXX/no-exceptions.cpp
index 097123d3fe523..e8ac8a657ab84 100644
--- a/clang/test/SemaCXX/no-exceptions.cpp
+++ b/clang/test/SemaCXX/no-exceptions.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -fsyntax-only -verify %s
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++20 %s
// Various tests for -fno-exceptions
@@ -30,5 +30,28 @@ void g() {
} catch (...) {
}
}
+}
+
+namespace test2 {
+template <auto enable> void foo(auto &&Fnc) {
+ if constexpr (enable)
+ try {
+ Fnc();
+ } catch (...) {
+ }
+ else
+ Fnc();
+}
+
+void bar1() {
+ foo<false>([] {});
+}
+template <typename T> void foo() {
+ try { // expected-error {{cannot use 'try' with exceptions disabled}}
+ } catch (...) {
+ }
+ throw 1; // expected-error {{cannot use 'throw' with exceptions disabled}}
+}
+void bar2() { foo<int>(); } // expected-note {{in instantiation of function template specialization 'test2::foo<int>' requested here}}
}
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