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| author | Marek Polacek <polacek@redhat.com> | 2020-04-19 18:46:40 -0400 |
|---|---|---|
| committer | Marek Polacek <polacek@redhat.com> | 2020-05-07 14:15:37 -0400 |
| commit | 5d5dcc65aae1024da31e0e9cae6a8966461037e8 (patch) | |
| tree | fb7af4ad2866a940fc07338d26f5e1ff224325d1 | |
| parent | 21968d4ae067e3fa1c1728c8db26478e8ac8ad0b (diff) | |
| download | gcc-5d5dcc65aae1024da31e0e9cae6a8966461037e8.zip gcc-5d5dcc65aae1024da31e0e9cae6a8966461037e8.tar.gz gcc-5d5dcc65aae1024da31e0e9cae6a8966461037e8.tar.bz2 | |
c++: Detect long double -> double narrowing [PR94590]
This PR points out that we don't detect long double -> double narrowing
when long double happens to have the same precision as double; on x86_64
this can be achieved by -mlong-double-64.
[dcl.init.list]#7.2 specifically says "from long double to double or float,
or from double to float", but check_narrowing only checks
TYPE_PRECISION (type) < TYPE_PRECISION (ftype)
so we need to handle the other cases too, e.g. by same_type_p as in
the following patch.
PR c++/94590 - Detect long double -> double narrowing.
* typeck2.c (check_narrowing): Detect long double -> double
narrowing even when double and long double have the same
precision. Make it handle conversions to float too.
* g++.dg/cpp0x/Wnarrowing18.C: New test.
| -rw-r--r-- | gcc/cp/ChangeLog | 7 | ||||
| -rw-r--r-- | gcc/cp/typeck2.c | 9 | ||||
| -rw-r--r-- | gcc/testsuite/ChangeLog | 5 | ||||
| -rw-r--r-- | gcc/testsuite/g++.dg/cpp0x/Wnarrowing18.C | 15 |
4 files changed, 35 insertions, 1 deletions
diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog index 7454352..031741e 100644 --- a/gcc/cp/ChangeLog +++ b/gcc/cp/ChangeLog @@ -1,5 +1,12 @@ 2020-05-07 Marek Polacek <polacek@redhat.com> + PR c++/94590 - Detect long double -> double narrowing. + * typeck2.c (check_narrowing): Detect long double -> double + narrowing even when double and long double have the same + precision. Make it handle conversions to float too. + +2020-05-07 Marek Polacek <polacek@redhat.com> + PR c++/94255 * parser.c (cp_parser_class_specifier_1): Check that the scope is nested inside current scope before pushing it. diff --git a/gcc/cp/typeck2.c b/gcc/cp/typeck2.c index acf4414..d407e4c 100644 --- a/gcc/cp/typeck2.c +++ b/gcc/cp/typeck2.c @@ -1008,10 +1008,17 @@ check_narrowing (tree type, tree init, tsubst_flags_t complain, || !int_fits_type_p (init, type))) ok = false; } + /* [dcl.init.list]#7.2: "from long double to double or float, or from + double to float". */ else if (TREE_CODE (ftype) == REAL_TYPE && TREE_CODE (type) == REAL_TYPE) { - if (TYPE_PRECISION (type) < TYPE_PRECISION (ftype)) + if ((same_type_p (ftype, long_double_type_node) + && (same_type_p (type, double_type_node) + || same_type_p (type, float_type_node))) + || (same_type_p (ftype, double_type_node) + && same_type_p (type, float_type_node)) + || (TYPE_PRECISION (type) < TYPE_PRECISION (ftype))) { if (TREE_CODE (init) == REAL_CST) { diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index bed2d90..6712c1d 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,5 +1,10 @@ 2020-05-07 Marek Polacek <polacek@redhat.com> + PR c++/94590 - Detect long double -> double narrowing. + * g++.dg/cpp0x/Wnarrowing18.C: New test. + +2020-05-07 Marek Polacek <polacek@redhat.com> + PR c++/94255 * g++.dg/template/spec41.C: New test. diff --git a/gcc/testsuite/g++.dg/cpp0x/Wnarrowing18.C b/gcc/testsuite/g++.dg/cpp0x/Wnarrowing18.C new file mode 100644 index 0000000..0dc7075 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/Wnarrowing18.C @@ -0,0 +1,15 @@ +// PR c++/94590 - Detect long double -> double narrowing. +// { dg-do compile { target c++11 } } +// { dg-additional-options "-mlong-double-64" { target x86_64-*-* i?86-*-* } } + +int +main () +{ + using T = long double; + extern long double ld; + extern T ld2; + extern const T ld3; + double d{ld}; // { dg-error "narrowing conversion" } + double d2{ld2}; // { dg-error "narrowing conversion" } + double d3{ld3}; // { dg-error "narrowing conversion" } +} |