https://github.com/mygitljf created
https://github.com/llvm/llvm-project/pull/199104
## Summary
Fix a clang-format assertion crash when an ObjC `@interface` or
`@implementation` body contains a `-` or `+` that is not followed by `(`
or an identifier.
## Problem
`clang-format` aborts on inputs like:
```objc
@interface;
-
```
with:
```
Assertion `FormatTok->isOneOf(tok::l_paren, tok::identifier) &&
"'(' or identifier expected."' failed.
```
`UnwrappedLineParser::parseObjCUntilAtEnd()` consumes the `-`/`+` and
unconditionally calls `parseObjCMethod()`, whose entry `assert` requires
the next token to be `(` or an identifier. Malformed input (EOF, `;`,
`@end`, ...) violates that contract and aborts the process.
This is reachable from clangd's `textDocument/formatting` path while a
user is mid-typing a method declaration, so it shows up in real
editing sessions, not just hand-crafted reproducers.
## Solution
Guard the call site so `parseObjCMethod()` is only entered when its
entry contract is satisfied. The entry assertion stays as-is — the
contract is enforced by the caller, matching how the other ObjC
sub-parsers in this file (`parseObjCProtocolList`,
`parseObjCLightweightGenerics`, ...) gate their own entry conditions.
```diff
} else if (FormatTok->isOneOf(tok::minus, tok::plus)) {
nextToken();
- parseObjCMethod();
+ if (FormatTok->isOneOf(tok::l_paren, tok::identifier))
+ parseObjCMethod();
}
```
Malformed `-`/`+` tokens fall through to the next iteration of
`parseObjCUntilAtEnd`, which terminates naturally on `@end` or EOF.
## Testing
- New `FormatTestObjC.NoCrashOnStrayMethodSign` covers all 6 variants
reported in the issue.
- `FormatTests` — 1265/1265 pass (incl. 27 `FormatTestObjC`).
- `check-clang-format` (lit) — 33/33 pass.
- Manual reproduction of every variant in the issue now exits 0
with no abort.
Fixes #199075
>From e4eb2faec142d472d4e6e935e287f369e34334b8 Mon Sep 17 00:00:00 2001
From: mygitljf <[email protected]>
Date: Thu, 21 May 2026 20:05:47 +0000
Subject: [PATCH] [clang-format][ObjC] Fix assertion crash on stray '-'/'+' in
@interface body
UnwrappedLineParser::parseObjCUntilAtEnd() consumes a leading '-' or '+'
and unconditionally calls parseObjCMethod(), whose entry assertion
requires the next token to be '(' or an identifier. Malformed input
such as '@interface;\n-' violates that contract and aborts.
Guard the call site so parseObjCMethod() is only entered when its
entry contract is satisfied; the entry assertion itself is preserved.
Stray '-'/'+' tokens fall through to the next iteration of the
parseObjCUntilAtEnd loop and are absorbed by '@end' or EOF.
Adds a regression test (FormatTestObjC.NoCrashOnStrayMethodSign)
covering all variants reported in the issue.
Fixes #199075
---
clang/lib/Format/UnwrappedLineParser.cpp | 6 +++++-
clang/unittests/Format/FormatTestObjC.cpp | 12 ++++++++++++
2 files changed, 17 insertions(+), 1 deletion(-)
diff --git a/clang/lib/Format/UnwrappedLineParser.cpp
b/clang/lib/Format/UnwrappedLineParser.cpp
index 9536a233def58..3fb719c2a67a2 100644
--- a/clang/lib/Format/UnwrappedLineParser.cpp
+++ b/clang/lib/Format/UnwrappedLineParser.cpp
@@ -4262,7 +4262,11 @@ void UnwrappedLineParser::parseObjCUntilAtEnd() {
addUnwrappedLine();
} else if (FormatTok->isOneOf(tok::minus, tok::plus)) {
nextToken();
- parseObjCMethod();
+ // Guard against malformed input where '-'/'+' is not followed by a
+ // method declaration. parseObjCMethod() asserts the next token is '('
+ // or an identifier; silently skip the stray sign token otherwise.
+ if (FormatTok->isOneOf(tok::l_paren, tok::identifier))
+ parseObjCMethod();
} else {
parseStructuralElement();
}
diff --git a/clang/unittests/Format/FormatTestObjC.cpp
b/clang/unittests/Format/FormatTestObjC.cpp
index 09a9687d6f87a..b6aa96f5aea79 100644
--- a/clang/unittests/Format/FormatTestObjC.cpp
+++ b/clang/unittests/Format/FormatTestObjC.cpp
@@ -1803,6 +1803,18 @@ TEST_F(FormatTestObjC, AttributesOnObjCProperty) {
"@property(weak) id delegate ATTRIBUTE_MACRO(X) __attribute__((X));");
}
+TEST_F(FormatTestObjC, NoCrashOnStrayMethodSign) {
+ // Issue #199075: clang-format used to assert in parseObjCMethod() when an
+ // ObjC interface/implementation contained a '-' or '+' that was not
+ // followed by '(' or an identifier.
+ verifyNoCrash("@interface;\n-");
+ verifyNoCrash("@interface Foo\n-");
+ verifyNoCrash("@interface Foo\n+");
+ verifyNoCrash("@implementation Foo\n-");
+ verifyNoCrash("@interface Foo\n-\n@end");
+ verifyNoCrash("@interface Foo\n- ;");
+}
+
} // end namespace
} // namespace test
} // end namespace format
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