fix build: pass compiler.cppstd=20 to conan

commit_hash:de01b5c7aa9b6ed8cc00cf9920c64e0726c0208c

Author: Anton3

.github/workflows/ci-conan.yml

@@ -74,7 +74,7 @@ jobs:
           - name: Run conan
             run: |
                 ${{ matrix.container && 'sudo -u test-user' }} git config --global --add safe.directory `pwd`
-                ${{ matrix.container && 'sudo -u test-user' }} conan create . --update --build=missing --version=`cat version.txt` -s:a compiler.cppstd=17 -pr:b=default ${{matrix.conanflags}}
+                ${{ matrix.container && 'sudo -u test-user' }} conan create . --update --build=missing --version=`cat version.txt` -s:a compiler.cppstd=20 -pr:b=default ${{matrix.conanflags}}
 
           - name: Install test dependencies
             if: matrix.os == 'ubuntu-22.04'
@@ -120,7 +120,7 @@ jobs:
                     s3api \
                 ; do
                     mv conanfile.py $SAMPLE/
-                    echo "Run: ${{ matrix.container && 'sudo -u test-user' }} ${{matrix.tests-env}} conan test --build=never -s:a compiler.cppstd=17 -pr:b=default ${{matrix.conanflags}} $SAMPLE/ ${USERVER_VERSION}"
-                    ${{ matrix.container && 'sudo -u test-user' }} ${{matrix.tests-env}} conan test --build=never -s:a compiler.cppstd=17 -pr:b=default ${{matrix.conanflags}} $SAMPLE/ ${USERVER_VERSION}
+                    echo "Run: ${{ matrix.container && 'sudo -u test-user' }} ${{matrix.tests-env}} conan test --build=never -s:a compiler.cppstd=20 -pr:b=default ${{matrix.conanflags}} $SAMPLE/ ${USERVER_VERSION}"
+                    ${{ matrix.container && 'sudo -u test-user' }} ${{matrix.tests-env}} conan test --build=never -s:a compiler.cppstd=20 -pr:b=default ${{matrix.conanflags}} $SAMPLE/ ${USERVER_VERSION}
                     mv $SAMPLE/conanfile.py ./
                 done

conanfile.py

@@ -4,6 +4,7 @@
 
 from conan import ConanFile
 from conan.errors import ConanInvalidConfiguration
+from conan.tools.build import check_min_cppstd
 from conan.tools.cmake import CMake
 from conan.tools.cmake import cmake_layout
 from conan.tools.cmake import CMakeDeps
@@ -184,6 +185,8 @@ def build_requirements(self):
         self.tool_requires('protobuf/<host_version>')
 
     def validate(self):
+        check_min_cppstd(self, 20)
+
         if self.settings.os == 'Windows':
             raise ConanInvalidConfiguration(
                 'userver cannot be built on Windows',

scripts/docs/en/userver/build/build.md

@@ -431,6 +431,7 @@ To build the userver Conan package run the following in the userver root directo
 
 ```shell
 conan profile detect && conan profile show
+conan profile update settings.compiler.cppstd=20 default
 conan create . --build=missing --version=`cat version.txt` -pr:b=default
 ```