After building clang-uml from src with custom LLVM-21 there are errors

[gopalak]

I rebuilt clang-unl with custom llvm-21 (enabling RTTI etc) and rebuilt clang-uml - but now see these errors

[ERROR] /opt/gcc-15/include/c++/15.2.1/optional:1683: lambda expression in an unevaluated operand
[ERROR] /opt/gcc-15/include/c++/15.2.1/chrono:2372: call to consteval function 'std::chrono::hh_mm_ss::_S_fractional_width' is not a constant expression
[NOTE] /opt/gcc-15/include/c++/15.2.1/chrono:2372: undefined function '_S_fractional_width' cannot be used in a constant expression
This is the same gcc compiler I built clang-uml with tho

The gcc used is same as listed above.

[bkryza]

@gopalak I tried to reproduce the issue on my Ubuntu 24.04, I've built gcc-15 locally with the latest tag (15.2.0), and created a sample project:

main.cc:

#include <optional>
#include <string>

struct A {
    std::optional<std::string> val;
};


int main() {
    A a;

    return 0;
}

CMakeLists.txt:

cmake_minimum_required(VERSION 3.28)
project(test LANGUAGES CXX)

# Set the C++ standard
set(CMAKE_CXX_STANDARD 23)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_CXX_EXTENSIONS OFF)

# Add the executable target
add_executable(test main.cc)

.clang-uml:

compilation_database_dir: build
output_directory: docs/diagrams
diagrams:
  example_class_diagram:
    type: class
    glob:
      - main.cc
    include:
      paths:
        - .
    exclude:
      namespaces:
        - std

I generated compile commands using:

$ /home/bartek/devel/gcc/gcc-15/usr/bin/g++ --version
g++ (GCC) 15.2.0
Copyright (C) 2025 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ mkdir build && cd build
$ CC=/home/bartek/devel/gcc/gcc-15/usr/bin/gcc CXX=/home/bartek/devel/gcc/gcc-15/usr/bin/g++ cmake -DCMAKE_EXPORT_COMPILE_COMMANDS=ON ..

and then ran clang-uml - the correct diagram was generated without issues:

@startuml
class "A" as C_0006919333181322027406
class C_0006919333181322027406 {
__
+val : std::optional<std::string>
}

'Generated with clang-uml, version 0.6.2-25-g5e2993e
'LLVM version Ubuntu clang version 21.1.1 (++20250908083528+fa462a66e418-1~exp1~20250908083545.29)
@enduml

Could you check if this simple project does or doesn't work in your setup? Also, from your logs it seems you have GCC 15.2.1 - but the latest tagged version I found here was 15.2.0...

[gopalak]

I still see same errors in the std optional header file
clang-uml -p -v
Processing translation units and generating diagrams:
example_class_diagram [██████████████████████████████████-] [00m:00s] 1/1 ✗

ERROR: Failed to generate class diagram 'example_class_diagram' due to following issues:

• [ERROR] /opt/gcc-15/include/c++/15.2.1/optional:1683: lambda expression in an unevaluated operand

[gopalak]

I checked github for CXX and this line is there and of course gets installed at line 1683 when built. I actually pulled the tag 15.2.0 and it does have the line reported above in the same line number. I also see more errors from chrono etc but I am not sure how ur stuff is working may be because you are at C++ 23 standard

[bkryza]

@gopalak I'll investigate further, can you share some more information:

• output of clang-uml --version
• output of ldd clang-uml
• output of cat build/compile_commands.json

?

[gopalak]

There is a double free -- pls check

---

clang-uml 0.6.2-25-g5e2993e
Copyright (C) 2021-2025 Bartek Kryza bkryza@gmail.com
Linux x86_64 5.15.0-156-generic
Built against LLVM/Clang libraries version: 21.1.2
Using LLVM/Clang libraries version: clang version 21.1.2 (https://github.com/llvm/llvm-project.git b708aea0bc7127adf4ec643660699c8bcdde1273)
free(): double free detected in tcache 2
[1] 3883718 abort (core dumped) ./release/src/clang-uml --version

---

linux-vdso.so.1 (0x00007fffecd58000)
libyaml-cpp.so.0.6 => /lib/x86_64-linux-gnu/libyaml-cpp.so.0.6 (0x00007f470f300000)
libclang-cpp.so.21.1 => /opt/llvm-21/lib/libclang-cpp.so.21.1 (0x00007f470702e000)
librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007f4707024000)
libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f470701e000)
libz.so.1 => /opt/3p/lib/libz.so.1 (0x00007f4707000000)
libzstd.so.1 => /opt/3p/lib/libzstd.so.1 (0x00007f4706d1c000)
libxml2.so.2 => /opt/3p/lib/libxml2.so.2 (0x00007f4706b7c000)
libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f4706b59000)
libstdc++.so.6 => /opt//gcc-15/lib64/libstdc++.so.6 (0x00007f47068c8000)
libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f4706779000)
libgcc_s.so.1 => /opt//gcc-15/lib64/libgcc_s.so.1 (0x00007f470674c000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f470655a000)
/lib64/ld-linux-x86-64.so.2 (0x00007f470f36e000)

---

Did u need compile cmds of clang-uml or the test ?

[bkryza]

@gopalak I meant for the test project, to see what flags are added there on your system.

Also, can you try to run clang-uml with the option --query-driver . ?

[gopalak]

I have moved a bit more farther, the test program class diagram is now generated when I use query-driver.
But for my code we have SSL include in a separate dir and its found in -I in compile commands. json but clang-uml seems to pick on system install ssl include dir. How do I force my include to precede as my code compiles with the compile DB as its generated via our Makefile. I see it in the JSON file.

[bkryza]

@gopalak Glad to hear there is some progress, you can override the compile flags from compilation database using add_compile_flags and remove_compile_flags options which can be passed on command line or specified in the .clang-uml:

clang-uml --add-compile-flag -I/opt/my_toolchain/include \
          --remove-compile-flag -I/usr/include ...

or

add_compile_flags:
  - -I/opt/my_toolchain/include
remove_compile_flags:
  - -I/usr/include
  - r: "-m.*"

Try adding your custom SSL include paths with --add-compile-flag -I/opt/customssl/include and see if it helps.

[gopalak]

Ok will try in a bit. By the way which section do I add these in script file to read

[bkryza]

@gopalak Can be at the top like here:

clang-uml/.clang-uml

Lines 4 to 10 in 5e2993e

	add_compile_flags:
	- -fparse-all-comments
	- -Wno-deprecated-declarations
	- -Wno-ignored-optimization-argument
	remove_compile_flags:
	- -Wno-class-memaccess
	- -Wno-dangling-reference

[gopalak]

Issue I see is if I say we’re to remove /usr/include there are system headers which also come from there. How do I add my custom include path earlier as my compile commands use those in that order. Why does clang-uml not honoring that order from compile commands ?

Cheers
Gops

[bkryza]

clang-uml just passes the options to Clang, however all options you add with add_compile_flags will be added right after the compiler path, i.e. before all other flags from compile commands:

clang-uml/src/common/compilation_database.cc

Lines 154 to 162 in 5e2993e

	if (config().add_compile_flags && !config().add_compile_flags().empty()) {
	for (auto &compile_command : commands) {
	compile_command.CommandLine.insert(
	// Add flags after argv[0]
	compile_command.CommandLine.begin() + 1,
	config().add_compile_flags().begin(),
	config().add_compile_flags().end());
	}
	}

[gopalak]

Well doesnt look like - I tried both command line and adding add_compile_flags in .clang-uml which is /opt/3p/include
I checked the compile args and the version of SSL we include is clearly in the compile command and hence the code gets compiled but clang-uml still goes picks the SSL header from /usr/include/openssl -> I even tried just one src file in our project - I see errors from gcc-15.2.1 header files --
[ERROR] /opt/gcc-15/lib/gcc/x86_64-pc-linux-gnu/15.2.1/include/mmintrin.h:79: use of undeclared identifier '__builtin_ia32_vec_init_v2si'

This is same as gcc-15.2.0 so I am not sure as this is like opening a pandora's box now. I have the most min imal src which has a main to init some libs to generate class diagram and I cant get past it.

Is there a way we can print the actual command line compile commands options clang-uml is using.

One more thing I figured -> the same src file, if I just have it in compile_commands.json it gets parsed but if I have it as part of the whole project, it fails with incorrect ssl include path being used which just doesnt make sense.
I use the same params for both runs:

clang-uml --query-driver . -p --verbose
--add-compile-flag "-I/opt/3p/include" --remove-compile-flag "-I/usr/include"

ANd still no dice.

[bkryza]

@gopalak Can you try using -isystem instead of -I, i.e.

clang-uml --query-driver . -vv --add-compile-flag "-isystem/opt/3p/include" --remove-compile-flag "-isystem/usr/include"

Also to see detailed logs you have to remove -p.

[gopalak]

A little bit more progress -- I now use cmd line --
/opt/code/clang-uml/release/src/clang-uml --query-driver="/opt/gcc-15/bi
n/g++" --add-compile-flag "-isystem/opt/3p/include" -vv

But I am unable to skip files which has test and Test in their names : The exclude elements: schema throws an error
when I have
exclude:
elements:

• r: ".(test|Test)." or r: ".[tT]est."

I have test src code which has test and Test in their file names
same with directories

errorr --
[debug] [tid 562689] [yaml_decoders.cc:1243] Effective config file path is /opt/code/dp_0925/dataplane/obj/.clang-uml
ERROR: Invalid schema:

/diagrams.nsproxy_class_diagram: expected value type: diagram_t
failed variant 0:
/diagrams.nsproxy_class_diagram.exclude.paths.0: expected value type: string
failed variant 1:
/diagrams.nsproxy_class_diagram.type: expected value: sequence_diagram_t
/diagrams.nsproxy_class_diagram.exclude.paths.0: expected value type: string
failed variant 2:
/diagrams.nsproxy_class_diagram.type: expected value: package_diagram_t
/diagrams.nsproxy_class_diagram.exclude.paths.0: expected value type: string
failed variant 3:
/diagrams.nsproxy_class_diagram.type: expected value: include_diagram_t
/diagrams.nsproxy_class_diagram.exclude.paths.0: expected value type: string
I still see some files throw error on

[ERROR] /opt/gcc-15/lib/gcc/x86_64-pc-linux-gnu/15.2.1/include/mmintrin.h:79: use of undeclared identifier '__builtin_ia32_vec_init_v2si'
41149 - [ERROR] /opt/gcc-15/lib/gcc/x86_64-pc-linux-gnu/15.2.1/include/mmintrin.h:122: use of undeclared identifier '__builtin_ia32_vec_ext_v2si' 41150 - [ERROR] /opt/gcc-15/lib/gcc/x86_64-pc-linux-gnu/15.2.1/include/mmintrin.h:161: use of undeclared identifier '__builtin_ia32_packsswb'
41151 - [ERROR] /opt/gcc-15/lib/gcc/x86_64-pc-linux-gnu/15.2.1/include/mmintrin.h:176: use of undeclared identifier '__builtin_ia32_packssdw'
41152 - [ERROR] /opt/gcc-15/lib/gcc/x86_64-pc-linux-gnu/15.2.1/include/mmintrin.h:191: use of undeclared identifier '__builtin_ia32_packuswb'
41153 - [ERROR] /opt/gcc-15/lib/gcc/x86_64-pc-linux-gnu/15.2.1/include/mmintrin.h:205: use of undeclared identifier '__builtin_ia32_punpckhbw'; di d you mean '__builtin_ia32_kunpckhi'?
41154 - [ERROR] /opt/gcc-15/lib/gcc/x86_64-pc-linux-gnu/15.2.1/include/mmintrin.h:205: cannot initialize
WHich seems strange