[clang] [clang] Catch missing format attributes (PR #70024)

[LLVM Continuous Integration via cfe-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-solaris11-sparcv9` running on `solaris11-sparcv9` while building `clang` at step 5 "ninja check 1".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/13/builds/686

Here is the relevant piece of the build log for the reference:
```
Step 5 (ninja check 1) failure: stage 1 checked (failure)
******************** TEST 'Clang :: Sema/attr-format-missing.c' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
RUN: at line 1: /opt/llvm-buildbot/home/solaris11-sparcv9/clang-solaris11-sparcv9/stage1/bin/clang -cc1 -internal-isystem /opt/llvm-buildbot/home/solaris11-sparcv9/clang-solaris11-sparcv9/stage1/lib/clang/19/include -nostdsysteminc -fsyntax-only -verify=expected,c_diagnostics -Wmissing-format-attribute /opt/llvm-buildbot/home/solaris11-sparcv9/clang-solaris11-sparcv9/llvm/clang/test/Sema/attr-format-missing.c
+ /opt/llvm-buildbot/home/solaris11-sparcv9/clang-solaris11-sparcv9/stage1/bin/clang -cc1 -internal-isystem /opt/llvm-buildbot/home/solaris11-sparcv9/clang-solaris11-sparcv9/stage1/lib/clang/19/include -nostdsysteminc -fsyntax-only -verify=expected,c_diagnostics -Wmissing-format-attribute /opt/llvm-buildbot/home/solaris11-sparcv9/clang-solaris11-sparcv9/llvm/clang/test/Sema/attr-format-missing.c
RUN: at line 2: /opt/llvm-buildbot/home/solaris11-sparcv9/clang-solaris11-sparcv9/stage1/bin/clang -cc1 -internal-isystem /opt/llvm-buildbot/home/solaris11-sparcv9/clang-solaris11-sparcv9/stage1/lib/clang/19/include -nostdsysteminc -fsyntax-only -Wmissing-format-attribute -fdiagnostics-parseable-fixits /opt/llvm-buildbot/home/solaris11-sparcv9/clang-solaris11-sparcv9/llvm/clang/test/Sema/attr-format-missing.c 2>&1 | /opt/llvm-buildbot/home/solaris11-sparcv9/clang-solaris11-sparcv9/stage1/bin/FileCheck /opt/llvm-buildbot/home/solaris11-sparcv9/clang-solaris11-sparcv9/llvm/clang/test/Sema/attr-format-missing.c --check-prefixes=CHECK,C-CHECK
+ /opt/llvm-buildbot/home/solaris11-sparcv9/clang-solaris11-sparcv9/stage1/bin/clang -cc1 -internal-isystem /opt/llvm-buildbot/home/solaris11-sparcv9/clang-solaris11-sparcv9/stage1/lib/clang/19/include -nostdsysteminc -fsyntax-only -Wmissing-format-attribute -fdiagnostics-parseable-fixits /opt/llvm-buildbot/home/solaris11-sparcv9/clang-solaris11-sparcv9/llvm/clang/test/Sema/attr-format-missing.c
+ /opt/llvm-buildbot/home/solaris11-sparcv9/clang-solaris11-sparcv9/stage1/bin/FileCheck /opt/llvm-buildbot/home/solaris11-sparcv9/clang-solaris11-sparcv9/llvm/clang/test/Sema/attr-format-missing.c --check-prefixes=CHECK,C-CHECK
RUN: at line 3: /opt/llvm-buildbot/home/solaris11-sparcv9/clang-solaris11-sparcv9/stage1/bin/clang -cc1 -internal-isystem /opt/llvm-buildbot/home/solaris11-sparcv9/clang-solaris11-sparcv9/stage1/lib/clang/19/include -nostdsysteminc -fsyntax-only -x c++ -verify=expected,cpp_diagnostics -Wmissing-format-attribute /opt/llvm-buildbot/home/solaris11-sparcv9/clang-solaris11-sparcv9/llvm/clang/test/Sema/attr-format-missing.c
+ /opt/llvm-buildbot/home/solaris11-sparcv9/clang-solaris11-sparcv9/stage1/bin/clang -cc1 -internal-isystem /opt/llvm-buildbot/home/solaris11-sparcv9/clang-solaris11-sparcv9/stage1/lib/clang/19/include -nostdsysteminc -fsyntax-only -x c++ -verify=expected,cpp_diagnostics -Wmissing-format-attribute /opt/llvm-buildbot/home/solaris11-sparcv9/clang-solaris11-sparcv9/llvm/clang/test/Sema/attr-format-missing.c
error: 'cpp_diagnostics-error' diagnostics seen but not expected: 
  File /opt/llvm-buildbot/home/solaris11-sparcv9/clang-solaris11-sparcv9/llvm/clang/test/Sema/attr-format-missing.c Line 87: subscript of pointer to incomplete type 'void'
  File /opt/llvm-buildbot/home/solaris11-sparcv9/clang-solaris11-sparcv9/llvm/clang/test/Sema/attr-format-missing.c Line 95: subscript of pointer to incomplete type 'void'
  File /opt/llvm-buildbot/home/solaris11-sparcv9/clang-solaris11-sparcv9/llvm/clang/test/Sema/attr-format-missing.c Line 96: subscript of pointer to incomplete type 'void'
error: 'cpp_diagnostics-warning' diagnostics expected but not seen: 
  File /opt/llvm-buildbot/home/solaris11-sparcv9/clang-solaris11-sparcv9/llvm/clang/test/Sema/attr-format-missing.c Line 83 (directive at /opt/llvm-buildbot/home/solaris11-sparcv9/clang-solaris11-sparcv9/llvm/clang/test/Sema/attr-format-missing.c:87): diagnostic behavior may be improved by adding the 'scanf' format attribute to the declaration of 'f7'
4 errors generated.

--

********************


```

https://github.com/llvm/llvm-project/pull/70024