[clang] [clang]Fix name lookup crash (PR #190484)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Serosh (Serosh-commits)

<details>
<summary>Changes</summary>

fix by guarding `CppNamespaceLookup` with an `isFileContext()` check instead of asserting
fixes #<!-- -->189344

---
Full diff: https://github.com/llvm/llvm-project/pull/190484.diff


3 Files Affected:

- (modified) clang/docs/ReleaseNotes.rst (+1) 
- (modified) clang/lib/Sema/SemaLookup.cpp (+1-4) 
- (added) clang/test/SemaCXX/gh189344.cpp (+7) 


``````````diff
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 899a4ee0dee0e..a7cda9b03715a 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -549,6 +549,7 @@ Bug Fixes to Attribute Support
 
 Bug Fixes to C++ Support
 ^^^^^^^^^^^^^^^^^^^^^^^^
+- Fixed a name lookup crash when parsing invalid template parameters. (#GH189344)
 - Diagnose binding a reference to ``*nullptr`` during constant evaluation. (#GH48665)
 - Suppress ``-Wdeprecated-declarations`` in implicitly generated functions. (#GH147293)
 - Fix a crash when deleting a pointer to an incomplete array (#GH150359).
diff --git a/clang/lib/Sema/SemaLookup.cpp b/clang/lib/Sema/SemaLookup.cpp
index b9fac5a4a1153..a5c33d0738e2d 100644
--- a/clang/lib/Sema/SemaLookup.cpp
+++ b/clang/lib/Sema/SemaLookup.cpp
@@ -1528,10 +1528,7 @@ bool Sema::CppLookupName(LookupResult &R, Scope *S) {
         // If we have a context, and it's not a context stashed in the
         // template parameter scope for an out-of-line definition, also
         // look into that context.
-        if (!(Found && S->isTemplateParamScope())) {
-          assert(Ctx->isFileContext() &&
-              "We should have been looking only at file context here already.");
-
+        if (Ctx->isFileContext() && !(Found && S->isTemplateParamScope())) {
           // Look into context considering using-directives.
           if (CppNamespaceLookup(*this, R, Context, Ctx, UDirs))
             Found = true;
diff --git a/clang/test/SemaCXX/gh189344.cpp b/clang/test/SemaCXX/gh189344.cpp
new file mode 100644
index 0000000000000..19d1244fbc15d
--- /dev/null
+++ b/clang/test/SemaCXX/gh189344.cpp
@@ -0,0 +1,7 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+template <union { } alignas ( union  a { c ) ( a :: ) ( :: (b
+// expected-error at -1 {{cannot be defined in a type specifier}}
+// expected-error at -1 {{'a' cannot be defined in a type specifier}}
+// expected-error at -1 {{expected unqualified-id}}
+// expected-error at -1 {{expected unqualified-id}}

``````````

</details>


https://github.com/llvm/llvm-project/pull/190484