scan-build using scons uses gcc instead of clang

Question

I'm trying to make scan-build use clang instead of gcc for compiling, but for some reason scons always uses gcc.

If I execute scons, I get this:

scons: Reading SConscript files ...
scons: done reading SConscript files.
scons: Building targets ...
/usr/bin/clang++ -o src/game.o -c -std=c++1z -pedantic -Wall -Wextra -Werror -O3 src/game.cpp
src/game.cpp:13:62: error: unknown type name 'a'
constexpr std::array<piece_t, game::pieces_num> game::pieces;a
                                                             ^
src/game.cpp:15:7: error: constructor cannot have a return type
game::game() noexcept {
      ^~~~
src/game.cpp:16:5: error: use of undeclared identifier 'regen_pieces'
    regen_pieces();
    ^
3 errors generated.
scons: *** [src/game.o] Error 1
scons: building terminated because of errors.

As you can see, it correctly uses clang++ instead of g++. I achieved this using the answer in this question.

But, if I execute scan-build scons, I get this:

scan-build: Using '/usr/bin/clang-4.0' for static analysis
scons: Reading SConscript files ...
scons: done reading SConscript files.
scons: Building targets ...
/usr/bin/../lib/clang/c++-analyzer -o src/game.o -c -std=c++1z -pedantic -Wall -Wextra -Werror -O3 src/game.cpp
src/game.cpp:13:62: error: 'a' does not name a type
 constexpr std::array<piece_t, game::pieces_num> game::pieces;a
                                                              ^
scons: *** [src/game.o] Error 1
scons: building terminated because of errors.
scan-build: Removing directory '/tmp/scan-build-2017-04-27-213151-27247-1' because it contains no reports.
scan-build: No bugs found.

Because the error messages are different, scan-build used gcc instead of clang.

Here is my output for my environment variables:

$ printenv | grep clang
CC=/usr/bin/clang
CXX=/usr/bin/clang++

And my SConstruct file:

import os
env = Environment()
env["CC"] = os.getenv("CC") or env["CC"]
env["CXX"] = os.getenv("CXX") or env["CXX"]
env["ENV"].update(x for x in os.environ.items() if x[0].startswith("CCC_"))
env["ENV"]["TERM"] = os.environ["TERM"]
env.Append(CXXFLAGS = "-std=c++1z -pedantic -Wall -Wextra -Werror -O3")
env.Append(LIBS = ["pthread"])
env.Program("game", ["src/game.cpp", "src/main.cpp"])

So, my question is how can I make scan-build use clang?

Answer 1

If you don't specify a compiler, scan-build will not read the environment variables, but will instead guess. In your case, it guessed that the suitable compiler was gcc.

scan-build's developers are trying to fix this, but in the mean time, you have to explicitly specify the compiler when building:

$ scan-build --use-c++=clang++ scons