llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang
Author: Alejandro Álvarez Ayllón (alejandro-alvarez-sonarsource)
<details>
<summary>Changes</summary>
Treat them as namespaces: if they are at the beginning of the line, they are
likely a good recovery point.
For instance, in
```cpp
1.3.0
extern "C" {
extern int foo();
extern "C++" {
namespace bar {
void baz();
};
}
}
namespace {}
```
Everything until `namespace`... is gone from the AST. Headers (like libc's C++
`math.h`) can be included from an `extern "C"` contexts, and they do an `extern
"C++"` back again before including C++ headers (like `__type_traits`).
However, a malformed declaration just before the include (as the orphan `1.3.0`
in the example) causes everything from these standard libraries to go missing.
This patch updates the heuristic to try to recover from the first `extern`
keyword seen, pretty much as it is done for `namespace`.
CPP-4478
---
Full diff: https://github.com/llvm/llvm-project/pull/161641.diff
2 Files Affected:
- (modified) clang/lib/Parse/ParseDecl.cpp (+3)
- (added) clang/test/Parser/recovery-after-expected-unqualified-id.cpp (+9)
``````````diff
diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index 22c01c4e371f3..d6cd7eb8c2c3d 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -2083,6 +2083,9 @@ void Parser::SkipMalformedDecl() {
return;
break;
+ case tok::kw_extern:
+ // 'extern' at the start of a line is almost certainly a good
+ // place to pick back up parsing
case tok::kw_namespace:
// 'namespace' at the start of a line is almost certainly a good
// place to pick back up parsing, except in an Objective-C
diff --git a/clang/test/Parser/recovery-after-expected-unqualified-id.cpp
b/clang/test/Parser/recovery-after-expected-unqualified-id.cpp
new file mode 100644
index 0000000000000..8019b46df1e7b
--- /dev/null
+++ b/clang/test/Parser/recovery-after-expected-unqualified-id.cpp
@@ -0,0 +1,9 @@
+// RUN: %clang_cc1 -verify %s
+
+3.2 // expected-error {{expected unqualified-id}}
+
+extern "C" {
+ typedef int Int;
+}
+
+Int foo(); // Ok
``````````
</details>
https://github.com/llvm/llvm-project/pull/161641
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