[PATCH] D80925: Fix compiler crash when trying to parse alignment argument as a constant expression.

[Alexey Bataev via Phabricator via cfe-commits]

ABataev created this revision.
ABataev added reviewers: rjmccall, rsmith.
Herald added a project: clang.

Clang crashes when trying to finish function body. MaybeODRUseExprs is
not empty because of const static data member parsed in outer evaluation
context, upon call for isTypeIdInParens() function. It builds
annot_primary_expr, later parsed in ParseConstantExpression() in
inner constant expression evaluation context.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D80925

Files:
  clang/lib/Parse/ParseDecl.cpp
  clang/test/AST/alignas_maybe_odr_cleanup.cpp


Index: clang/test/AST/alignas_maybe_odr_cleanup.cpp
===================================================================
--- /dev/null
+++ clang/test/AST/alignas_maybe_odr_cleanup.cpp
@@ -0,0 +1,15 @@
+// RUN: %clang_cc1 -fsyntax-only %s -ast-dump | FileCheck %s
+
+struct FOO {
+  static const int vec_align_bytes = 32;
+  void foo() {
+    double a alignas(vec_align_bytes);
+    ;
+  }
+};
+
+// CHECK: AlignedAttr {{.*}} alignas
+// CHECK: ConstantExpr {{.+}} 'int' Int: 32
+// CHECK: ImplicitCastExpr {{.*}} 'int' <LValueToRValue>
+// CHECK: DeclRefExpr {{.*}} 'const int' lvalue Var {{.*}} 'vec_align_bytes' 'const int' non_odr_use_constant
+// CHECK: NullStmt
Index: clang/lib/Parse/ParseDecl.cpp
===================================================================
--- clang/lib/Parse/ParseDecl.cpp
+++ clang/lib/Parse/ParseDecl.cpp
@@ -2827,6 +2827,8 @@
 /// [C++0x] assignment-expression ...[opt]
 ExprResult Parser::ParseAlignArgument(SourceLocation Start,
                                       SourceLocation &EllipsisLoc) {
+  EnterExpressionEvaluationContext ConstantEvaluated(
+      Actions, Sema::ExpressionEvaluationContext::ConstantEvaluated);
   ExprResult ER;
   if (isTypeIdInParens()) {
     SourceLocation TypeLoc = Tok.getLocation();
@@ -2834,8 +2836,9 @@
     SourceRange TypeRange(Start, Tok.getLocation());
     ER = Actions.ActOnUnaryExprOrTypeTraitExpr(TypeLoc, UETT_AlignOf, true,
                                                Ty.getAsOpaquePtr(), TypeRange);
-  } else
-    ER = ParseConstantExpression();
+  } else {
+    ER = ParseConstantExpressionInExprEvalContext();
+  }
 
   if (getLangOpts().CPlusPlus11)
     TryConsumeToken(tok::ellipsis, EllipsisLoc);


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