www-client/firefox: fail if LLVM version used by clang and rust does not match

If LLVM version does not match, like seen with rust-1.47.0 which is based on
LLVM 11 but sys-devel/clang in Gentoo is still at version 10 because LLVM 11
is not yet released, linking will fail with errors like

  ld.lld: error: Invalid summary version 9. Version should be in the range [1-8]

or

  ld.lld: error: ../work/firefox_build/x86_64-unknown-linux-gnu/release/libgkrust.a(gkrust-6d42f0360e1be5e5.gkrust.3v9jvdvg-cgu.0.rcgu.o): Invalid record

Package-Manager: Portage-3.0.8, Repoman-3.0.1
Signed-off-by: Thomas Deutschmann <whissi@gentoo.org>

2 files changed, 38 insertions, 0 deletions

diff --git a/www-client/firefox/firefox-78.3.1.ebuild b/www-client/firefox/firefox-78.3.1.ebuild
index 99f7f8951b98..37b316bab979 100644
--- a/www-client/firefox/firefox-78.3.1.ebuild
+++ b/www-client/firefox/firefox-78.3.1.ebuild
@@ -393,6 +393,25 @@ pkg_setup() {
 
 		llvm_pkg_setup
 
+		if use clang && use lto ; then
+			local version_lld=$(ld.lld --version 2>/dev/null | awk '{ print $2 }')
+			[[ -n ${version_lld} ]] && version_lld=$(ver_cut 1 "${version_lld}")
+			[[ -z ${version_lld} ]] && die "Failed to read ld.lld version!"
+
+			local version_llvm_rust=$(rustc -Vv 2>/dev/null | grep -F -- 'LLVM version:' | awk '{ print $3 }')
+			[[ -n ${version_llvm_rust} ]] && version_llvm_rust=$(ver_cut 1 "${version_llvm_rust}")
+			[[ -z ${version_llvm_rust} ]] && die "Failed to read used LLVM version from rustc!"
+
+			if ver_test "${version_lld}" -ne "${version_llvm_rust}" ; then
+				eerror "Rust is using LLVM version ${version_llvm_rust} but ld.lld version belongs to LLVM version ${version_lld}."
+				eerror "You will be unable to link ${CATEGORY}/${PN}. To proceed you have the following options:"
+				eerror "  - Manually switch rust version using 'eselect rust' to match used LLVM version"
+				eerror "  - Switch to dev-lang/rust[system-llvm] which will guarantee matching version"
+				eerror "  - Build ${CATEGORY}/${PN} without USE=lto"
+				die "LLVM version used by Rust (${version_llvm_rust}) does not match with ld.lld version (${version_lld})!"
+			fi
+		fi
+
 		python-any-r1_pkg_setup
 
 		# Avoid PGO profiling problems due to enviroment leakage
diff --git a/www-client/firefox/firefox-81.0.1-r1.ebuild b/www-client/firefox/firefox-81.0.1-r1.ebuild
index 8ec1f4d60eb0..65702e05e323 100644
--- a/www-client/firefox/firefox-81.0.1-r1.ebuild
+++ b/www-client/firefox/firefox-81.0.1-r1.ebuild
@@ -393,6 +393,25 @@ pkg_setup() {
 
 		llvm_pkg_setup
 
+		if use clang && use lto ; then
+			local version_lld=$(ld.lld --version 2>/dev/null | awk '{ print $2 }')
+			[[ -n ${version_lld} ]] && version_lld=$(ver_cut 1 "${version_lld}")
+			[[ -z ${version_lld} ]] && die "Failed to read ld.lld version!"
+
+			local version_llvm_rust=$(rustc -Vv 2>/dev/null | grep -F -- 'LLVM version:' | awk '{ print $3 }')
+			[[ -n ${version_llvm_rust} ]] && version_llvm_rust=$(ver_cut 1 "${version_llvm_rust}")
+			[[ -z ${version_llvm_rust} ]] && die "Failed to read used LLVM version from rustc!"
+
+			if ver_test "${version_lld}" -ne "${version_llvm_rust}" ; then
+				eerror "Rust is using LLVM version ${version_llvm_rust} but ld.lld version belongs to LLVM version ${version_lld}."
+				eerror "You will be unable to link ${CATEGORY}/${PN}. To proceed you have the following options:"
+				eerror "  - Manually switch rust version using 'eselect rust' to match used LLVM version"
+				eerror "  - Switch to dev-lang/rust[system-llvm] which will guarantee matching version"
+				eerror "  - Build ${CATEGORY}/${PN} without USE=lto"
+				die "LLVM version used by Rust (${version_llvm_rust}) does not match with ld.lld version (${version_lld})!"
+			fi
+		fi
+
 		python-any-r1_pkg_setup
 
 		# Avoid PGO profiling problems due to enviroment leakage