id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
4667	boost-build: configuration of toolset gcc does not enforce requested versions and accepts non-existing commands	mhassert@…	Vladimir Prus	"When one configures toolset gcc with a non-existing command it is accepted and an error is not reported until compilation starts.

When one configures toolset gcc with a version but no command (e.g. from the command line), boost build silently uses default command g++ without any version checking.

Examples:

a)
- in ~/user-config.jam insert ""using gcc : 4.1 : gcc-4.1-FORCE-ERROR ;""
- run bjam --toolset=gcc-4.1 --debug-configuration -d+2
result: configuration of gcc-4.1 notices the not-found command but contuinues and later all compilations fail due to a ""command not found""

b)
- add ""using gcc : 9.9 ;"" to ~/user-config.jam and run ""bjam""
OR
- run bjam --toolset=gcc-9.9 --debug-configuration -d+2
result: auto configuration silently uses command ""g++"" but the version ""9.9"" is nontheless used in build paths tricking the user into thinking the requested compiler version was actually used.
This is especially dangerous as any typo in the version on the command line does result in using the default compiler instead of a previously configured one.

What should happen:
- If only a version is given, boost build should try to deduce the correct command:
""g++-VERSION"" and ""g++"" with matching version should be considered in that order.
- boost build should inform the user if the requested compiler command/version is not available and stop with an error.

I have attached a patch that changes tools/gcc.jam into what I think it should look like.

Note:
Several mails on the mailing list suggest that a similar problem exists with toolset msvc and probably other toolsets, too. For example using toolset=msvc-8 instead of toolset=msvc-8.0 seems to use some default version instead of using 8.0 or failing. As msvc configuration code seems quite different, I have not looked further into this."	Patches	closed	To Be Determined	build	Boost Development Trunk	Problem	fixed	bjam boost build boost-build gcc toolset version compiler