[BUG] ICE in clang::Parser::ParseDeclarationAfterDeclaratorAndAttributes(clang::Declarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::ForRangeInit*)

## Bug Report: ICE in clang::Parser::ParseDeclarationAfterDeclaratorAndAttributes(clang::Declarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::ForRangeInit*)

Clang crashes when compiling the following C code.

**Compiler**: clang-22 (LLVM 22.1.5, commit 5ea218a153f4d2f815b8244eab3e4b4ba5e00e6c)
**Compilation flags**: -O0
**Platform**: x86_64-linux-gnu
**Component**: frontend

This is a **frontend** crash (reproduces with `-emit-llvm -Xclang -disable-llvm-passes`).

## Reduced Test Case

> Minimized from the original fuzzer-generated input using `creduce`.

```sh
clang -O0 test.c -o /dev/null
```

```c
extern int a __attribute__((alias(""))) = 42

```

## Crash Output

```
/root/outputs/experiments-on-metamut/surfuzz,clang,3/DBbCyOwnsznl_surfuzz_14.c:8:12: error: redefinition of 'g1'
8 | extern int g1 __attribute__((alias("bar1"))) \= 42;
| ^
/root/outputs/experiments-on-metamut/surfuzz,clang,3/DBbCyOwnsznl_surfuzz_14.c:7:12: note: previous definition is here
7 | extern int g1 __attribute((alias("g0")));
| ^
clang-22: /root/compilers/llvm-project-release/clang/lib/Sema/SemaDecl.cpp:7151: void checkAliasAttr(clang::Sema&, clang::NamedDecl&): Assertion \`VD->isThisDeclarationADefinition() && !VD->isExternallyVisible() && "Broken AliasAttr handled late!"' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0\. Program arguments: /root/objects/llvm-project-release.obj/bin/clang-22 -cc1 -triple x86_64-unknown-linux-gnu -O0 -emit-obj -dumpdir /dev/null- -disable-free -clear-ast-before-backend -main-file-name DBbCyOwnsznl_surfuzz_14.c -mrelocation-model pic -pic-level 2 -pic-is-pie -mframe-pointer=all -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fdebug-compilation-dir=/root/data -fcoverage-compilation-dir=/root/data -resource-dir /root/objects/llvm-project-release.obj/lib/clang/22 -internal-isystem /root/objects/llvm-project-release.obj/lib/clang/22/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/12/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -ferror-limit 19 -fgnuc-version=4.2.1 -fskip-odr-check-in-gmf -faddrsig -fdwarf2-cfi-asm -o /tmp/DBbCyOwnsznl_surfuzz_14-abaef8.o -x c /root/outputs/experiments-on-metamut/surfuzz,clang,3/DBbCyOwnsznl_surfuzz_14.c
1\. /root/outputs/experiments-on-metamut/surfuzz,clang,3/DBbCyOwnsznl_surfuzz_14.c:8:50: current parser token ';'
#0 0x00005642915522d2 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/root/objects/llvm-project-release.obj/bin/clang-22+0x44f62d2)
#1 0x000056429154ecaf llvm::sys::RunSignalHandlers() (/root/objects/llvm-project-release.obj/bin/clang-22+0x44f2caf)
#2 0x000056429154edfc SignalHandler(int, siginfo_t*, void*) Signals.cpp:0:0
#3 0x00007fa5857fa520 (/usr/lib/x86_64-linux-gnu/libc.so.6+0x42520)
#4 0x00007fa58584ea7c __pthread_kill_implementation ./nptl/./nptl/pthread_kill.c:44:76
#5 0x00007fa58584ea7c __pthread_kill_internal ./nptl/./nptl/pthread_kill.c:78:10
#6 0x00007fa58584ea7c pthread_kill ./nptl/./nptl/pthread_kill.c:89:10
#7 0x00007fa5857fa476 gsignal ./signal/../sysdeps/posix/raise.c:27:6
#8 0x00007fa5857e07f3 abort ./stdlib/./stdlib/abort.c:81:7
#9 0x00007fa5857e071b _nl_load_domain ./intl/./intl/loadmsgcat.c:1177:9
#10 0x00007fa5857f1e96 (/usr/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
#11 0x000056429411f887 (/root/objects/llvm-project-release.obj/bin/clang-22+0x70c3887)
#12 0x000056429411f9a9 clang::Sema::FinalizeDeclaration(clang::Decl*) (/root/objects/llvm-project-release.obj/bin/clang-22+0x70c39a9)
#13 0x0000564293da9369 clang::Parser::ParseDeclarationAfterDeclaratorAndAttributes(clang::Declarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::ForRangeInit*) (/root/objects/llvm-project-release.obj/bin/clang-22+0x6d4d369)
#14 0x0000564293dc0ce3 clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&, clang::DeclaratorContext, clang::ParsedAttributes&, clang::Parser::ParsedTemplateInfo&, clang::SourceLocation*, clang::Parser::ForRangeInit*) (/root/objects/llvm-project-release.obj/bin/clang-22+0x6d64ce3)
#15 0x0000564293d797e1 clang::Parser::ParseDeclOrFunctionDefInternal(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec&, clang::AccessSpecifier) (/root/objects/llvm-project-release.obj/bin/clang-22+0x6d1d7e1)
#16 0x0000564293d7a00f clang::Parser::ParseDeclarationOrFunctionDefinition(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*, clang::AccessSpecifier) (/root/objects/llvm-project-release.obj/bin/clang-22+0x6d1e00f)
#17 0x0000564293d82896 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) (/root/objects/llvm-project-release.obj/bin/clang-22+0x6d26896)
#18 0x0000564293d83915 clang::Parser::ParseTopLevelDecl(clang::OpaquePtr&, clang::Sema::ModuleImportState&) (/root/objects/llvm-project-release.obj/bin/clang-22+0x6d27915)
#19 0x0000564293d6388a clang::ParseAST(clang::Sema&, bool, bool) (/root/objects/llvm-project-release.obj/bin/clang-22+0x6d0788a)
#20 0x00005642921db987 clang::FrontendAction::Execute() (/root/objects/llvm-project-release.obj/bin/clang-22+0x517f987)
#21 0x00005642921630e9 clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/root/objects/llvm-project-release.obj/bin/clang-22+0x51070e9)
#22 0x00005642922d895e clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/root/objects/llvm-project-release.obj/bin/clang-22+0x527c95e)
#23 0x000056428dfe3657 cc1_main(llvm::ArrayRef, char const*, void*) (/root/objects/llvm-project-release.obj/bin/clang-22+0xf87657)
#24 0x000056428dfd8694 ExecuteCC1Tool(llvm::SmallVectorImpl&, llvm::ToolContext const&, llvm::IntrusiveRefCntPtr) driver.cpp:0:0
#25 0x000056428dfdd907 clang_main(int, char**, llvm::ToolContext const&) (/root/objects/llvm-project-release.obj/bin/clang-22+0xf81907)
#26 0x000056428de9b0ea main (/root/objects/llvm-project-release.obj/bin/clang-22+0xe3f0ea)
#27 0x00007fa5857e1d90 __libc_start_call_main ./csu/../sysdeps/nptl/libc_start_call_main.h:58:16
#28 0x00007fa5857e1e40 call_init ./csu/../csu/libc-start.c:128:20
#29 0x00007fa5857e1e40 __libc_start_main ./csu/../csu/libc-start.c:379:5
#30 0x000056428dfd7cb5 _start (/root/objects/llvm-project-release.obj/bin/clang-22+0xf7bcb5)
clang: error: unable to execute command: Aborted (core dumped)
clang: error: clang frontend command failed due to signal (use -v to see invocation)
clang version 22.1.5 (https://github.com/llvm/llvm-project.git 5ea218a153f4d2f815b8244eab3e4b4ba5e00e6c)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /root/objects/llvm-project-release.obj/bin
Build config: \+assertions
clang: note: diagnostic msg:
********************
PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
Preprocessed source(s) and associated run script(s) are located at:
clang: note: diagnostic msg: /tmp/DBbCyOwnsznl_surfuzz_14-c5285a.c
clang: note: diagnostic msg: /tmp/DBbCyOwnsznl_surfuzz_14-c5285a.sh
clang: note: diagnostic msg:
********************
EXIT_CODE: 1
```

## Preprocessed Source & Run Script

**Preprocessed source** (`/tmp/DBbCyOwnsznl_surfuzz_14-c5285a.c`):

```c
# 1 ""
# 1 "/root/outputs/experiments-on-metamut/surfuzz,clang,3/DBbCyOwnsznl_surfuzz_14.c"
int g0;
const int f1 = 42;
static int bar1 = 42;
const int wacom_usb_ids[] = {1, 1, 2, 3, 5, 8, 13, 0};
extern const int __mod_usb_device_table __attribute__ ((alias("wacom_usb_ids")));
extern int g1;
extern int g1 __attribute((alias("g0")));
extern int g1 __attribute__((alias("bar1"))) = 42;
#define baz2 bar1
static const int __attribute__((alias("bar1"))) baz2 __attribute__((weak)) = 42;
extern int baz2 __attribute__((weak));
static int g1, g1a = 0 __attribute__((alias("g1")));
extern int g2 __attribute__((alias("baz2"))) = 0;
extern const int f4;
int f4 __attribute__((weakref));
void f0(void) { }
extern void f1(void);
extern void f1(void) __attribute((alias("f0")));
static inline int foo1() { return 0; }
int foo() __attribute__((alias("foo1")));
int bar() __attribute__((alias("bar1")));
extern int test6();
void test7() { test6(); }
int test6() __attribute__((alias("test7")));
static int inner(int a) { return 0; }
static int inner_weak(int a) { return 0; }
extern __typeof(inner) inner_a __attribute__((alias("inner")));
static __typeof(inner_weak) inner_weak_a __attribute__((weakref, alias("inner_weak")));
int outer(int a) { return inner(a); }
int outer_weak(int a) { return inner_weak_a(a); }
void test8_bar() {}
void test8_foo() __attribute__((weak, alias("test8_bar")));
void test8_zed() __attribute__((alias("test8_foo")));
void test9_bar(void) { }
void test9_zed(void) __attribute__((section("test")));
void test9_zed(void) __attribute__((alias("test9_bar")));
int test10;
static int test10_foo __attribute__((alias("test10")));
void test11(void) {}
static void test11_foo(void) __attribute__((alias("test11")));
void test12(void) {}
inline void test12_alias(void) __attribute__((gnu_inline, alias("test12")));
enum a_type { test13_a };
void test13(enum a_type y) {}
void test13_alias(enum undeclared_type y) __attribute__((alias ("test13")));

```

**Run script** (`/tmp/DBbCyOwnsznl_surfuzz_14-c5285a.sh`):

```sh
# Crash reproducer for clang version 22.1.5 (https://github.com/llvm/llvm-project.git 5ea218a153f4d2f815b8244eab3e4b4ba5e00e6c)
# Driver args: "-O0" "/root/outputs/experiments-on-metamut/surfuzz,clang,3/DBbCyOwnsznl_surfuzz_14.c" "-o" "/dev/null"
# Original command: "/root/objects/llvm-project-release.obj/bin/clang-22" "-cc1" "-triple" "x86_64-unknown-linux-gnu" "-O0" "-emit-obj" "-dumpdir" "/dev/null-" "-disable-free" "-clear-ast-before-backend" "-main-file-name" "DBbCyOwnsznl_surfuzz_14.c" "-mrelocation-model" "pic" "-pic-level" "2" "-pic-is-pie" "-mframe-pointer=all" "-fmath-errno" "-ffp-contract=on" "-fno-rounding-math" "-mconstructor-aliases" "-funwind-tables=2" "-target-cpu" "x86-64" "-tune-cpu" "generic" "-debugger-tuning=gdb" "-fdebug-compilation-dir=/root/data" "-fcoverage-compilation-dir=/root/data" "-resource-dir" "/root/objects/llvm-project-release.obj/lib/clang/22" "-internal-isystem" "/root/objects/llvm-project-release.obj/lib/clang/22/include" "-internal-isystem" "/usr/local/include" "-internal-isystem" "/usr/lib/gcc/x86_64-linux-gnu/12/../../../../x86_64-linux-gnu/include" "-internal-externc-isystem" "/usr/include/x86_64-linux-gnu" "-internal-externc-isystem" "/include" "-internal-externc-isystem" "/usr/include" "-ferror-limit" "19" "-fgnuc-version=4.2.1" "-fskip-odr-check-in-gmf" "-faddrsig" "-fdwarf2-cfi-asm" "-o" "/tmp/DBbCyOwnsznl_surfuzz_14-abaef8.o" "-x" "c" "/root/outputs/experiments-on-metamut/surfuzz,clang,3/DBbCyOwnsznl_surfuzz_14.c"
"/root/objects/llvm-project-release.obj/bin/clang-22" "-cc1" "-triple" "x86_64-unknown-linux-gnu" "-O0" "-emit-obj" "-dumpdir" "/dev/null-" "-disable-free" "-clear-ast-before-backend" "-main-file-name" "DBbCyOwnsznl_surfuzz_14.c" "-mrelocation-model" "pic" "-pic-level" "2" "-pic-is-pie" "-mframe-pointer=all" "-fmath-errno" "-ffp-contract=on" "-fno-rounding-math" "-mconstructor-aliases" "-funwind-tables=2" "-target-cpu" "x86-64" "-tune-cpu" "generic" "-debugger-tuning=gdb" "-fdebug-compilation-dir=/root/data" "-fcoverage-compilation-dir=/root/data" "-ferror-limit" "19" "-fgnuc-version=4.2.1" "-fskip-odr-check-in-gmf" "-faddrsig" "-fdwarf2-cfi-asm" "-x" "c" "DBbCyOwnsznl_surfuzz_14-c5285a.c"

```

* found via a fuzzer

[DBbCyOwnsznl_surfuzz_14-c5285a.c](https://github.com/user-attachments/files/29128320/DBbCyOwnsznl_surfuzz_14-c5285a.c)
[DBbCyOwnsznl_surfuzz_14-c5285a.sh](https://github.com/user-attachments/files/29128319/DBbCyOwnsznl_surfuzz_14-c5285a.sh)

Reproduce the crash with the reduced C case and the provided clang command. Start in clang/lib/Sema/SemaDecl.cpp at checkAliasAttr and follow the call from Parser::ParseDeclarationAfterDeclaratorAndAttributes. Done means the reduced input no longer triggers the assertion, with regression coverage for the reported alias declaration case.

Written by the indexing model from the issue text.