diff options
| author | Björn Gustavsson <[email protected]> | 2010-03-12 09:39:23 +0100 |
|---|---|---|
| committer | Björn Gustavsson <[email protected]> | 2010-06-02 11:51:25 +0200 |
| commit | 7ac0808979534a94617c3391503c961d1ef72755 (patch) | |
| tree | f929be0d00318569bef8d37ecf316512b17a1b19 /lib/stdlib | |
| parent | 1858cb81391d2bce29b4b7620574ca60128cebf7 (diff) | |
| download | otp-7ac0808979534a94617c3391503c961d1ef72755.tar.gz otp-7ac0808979534a94617c3391503c961d1ef72755.tar.bz2 otp-7ac0808979534a94617c3391503c961d1ef72755.zip | |
Evaluate element/2 at compile-time using type information
The erl_expand_records compiler pass translates the
following code:
h(X) when X#r1.a =:= 1 -> ok.
to (essentially):
h({r1,V1,V2}=X) when element(2, X) =:= 1 -> ok.
Since the guard can only be executed when the pattern matching
has succeeded, we know that the second element in the tuple X
must have been bound to V2. Thus we can eliminate the call
to element/2 like this:
h({r1,V1,V2}=X) when V1 =:= 1 -> ok.
Diffstat (limited to 'lib/stdlib')
| -rw-r--r-- | lib/stdlib/test/qlc_SUITE.erl | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/lib/stdlib/test/qlc_SUITE.erl b/lib/stdlib/test/qlc_SUITE.erl index aa12ed57da..e21de8770a 100644 --- a/lib/stdlib/test/qlc_SUITE.erl +++ b/lib/stdlib/test/qlc_SUITE.erl @@ -3184,7 +3184,9 @@ lookup2(Config) when is_list(Config) -> [] = qlc:e(Q), false = lookup_keys(Q) end, [{1,b},{2,3}])">>, - {warnings,[{{3,48},qlc,nomatch_filter}]}}, + {warnings,[{2,sys_core_fold,nomatch_guard}, + {3,qlc,nomatch_filter}, + {3,sys_core_fold,{eval_failure,badarg}}]}}, <<"etsc(fun(E) -> Q = qlc:q([X || {X} <- ets:table(E), element(1,{X}) =:= 1]), |