[Clang] Fix crash on improper use of __array_extent

[a-tarasyuk]

Fixes #80474

[llvmbot]

@llvm/pr-subscribers-clang

Author: Oleksandr T. (a-tarasyuk)

Changes

Fixes #80474

---

Full diff: https://github.com/llvm/llvm-project/pull/94173.diff

3 Files Affected:

• (modified) clang/docs/ReleaseNotes.rst (+1)
• (modified) clang/lib/Parse/ParseExprCXX.cpp (+3)
• (added) clang/test/SemaCXX/incomplete-array-extent.cpp (+5)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 0c700d23257bf..32515fbac64f6 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -823,6 +823,7 @@ Bug Fixes to C++ Support
   differering by their constraints when only one of these function was variadic.
 - Fix a crash when a variable is captured by a block nested inside a lambda. (Fixes #GH93625).
 - Fixed a type constraint substitution issue involving a generic lambda expression. (#GH93821)
+- Fix a crash caused by improper use of ``__array_extent``. (#GH80474)
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/Parse/ParseExprCXX.cpp b/clang/lib/Parse/ParseExprCXX.cpp
index 1558e3dcb8974..6f21a4f9bd826 100644
--- a/clang/lib/Parse/ParseExprCXX.cpp
+++ b/clang/lib/Parse/ParseExprCXX.cpp
@@ -4011,6 +4011,9 @@ ExprResult Parser::ParseArrayTypeTrait() {
     ExprResult DimExpr = ParseExpression();
     T.consumeClose();
 
+    if (DimExpr.isInvalid())
+      return ExprError();
+
     return Actions.ActOnArrayTypeTrait(ATT, Loc, Ty.get(), DimExpr.get(),
                                        T.getCloseLocation());
   }
diff --git a/clang/test/SemaCXX/incomplete-array-extent.cpp b/clang/test/SemaCXX/incomplete-array-extent.cpp
new file mode 100644
index 0000000000000..d59800f67a6ae
--- /dev/null
+++ b/clang/test/SemaCXX/incomplete-array-extent.cpp
@@ -0,0 +1,5 @@
+// RUN: %clang_cc1 -verify -std=c++11 %s
+
+auto f() { // expected-error {{'auto' return without trailing return type; deduced return types are a C++14 extension}}
+  return __array_extent(int, ); // expected-error {{expected expression}}
+}

[Sirraide]

LGTM

Though I do wonder how many other type traits are also affected by this, because at least the function below this one also doesn’t seem to check for parse errors... it would probably make sense to take a look at the rest of them too, but that can also be a separate pr.

[cor3ntin]

I've edited the title of the PR (which is then used as commit message)
Please follow that style in the future (see also https://llvm.org/docs/DeveloperPolicy.html#commit-messages)

The change itself looks fine, thanks!