diff options
| author | Jason Merrill <jason@redhat.com> | 2024-09-12 16:22:02 -0400 |
|---|---|---|
| committer | Jason Merrill <jason@redhat.com> | 2024-09-13 17:18:29 +0200 |
| commit | 4ee692337c4ec18fe9be3df34f3607ea3de5ef93 (patch) | |
| tree | ffeca15a6d15e6bd6ad63873e877fa00834b0dd6 | |
| parent | 99988464fc86354f0359c0fd91eee444fb5bd8a2 (diff) | |
| download | gcc-4ee692337c4ec18fe9be3df34f3607ea3de5ef93.zip gcc-4ee692337c4ec18fe9be3df34f3607ea3de5ef93.tar.gz gcc-4ee692337c4ec18fe9be3df34f3607ea3de5ef93.tar.bz2 | |
c++: -fimplicit-constexpr diagnostic improvement [PR116696]
PR116696 expressed surprise that explicit 'constexpr' was needed on one
function; this was because the function isn't 'inline', and
-fimplicit-constexpr doesn't try to promote non-inline functions. Let's be
more helpful in that situation, and also help trace through functions that
were promoted.
PR c++/116696
gcc/cp/ChangeLog:
* constexpr.cc (explain_invalid_constexpr_fn): When
-fimplicit-constexpr, also explain inline functions, and point out
non-inline functions.
gcc/testsuite/ChangeLog:
* g++.dg/DRs/dr2478.C: Prune extra diagnostic.
* g++.dg/ext/fimplicit-constexpr1.C: New test.
| -rw-r--r-- | gcc/cp/constexpr.cc | 7 | ||||
| -rw-r--r-- | gcc/testsuite/g++.dg/DRs/dr2478.C | 2 | ||||
| -rw-r--r-- | gcc/testsuite/g++.dg/ext/fimplicit-constexpr1.C | 8 |
3 files changed, 16 insertions, 1 deletions
diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc index db2a9c1..d0f6174 100644 --- a/gcc/cp/constexpr.cc +++ b/gcc/cp/constexpr.cc @@ -1057,9 +1057,16 @@ explain_invalid_constexpr_fn (tree fun) /* Only diagnose defaulted functions, lambdas, or instantiations. */ else if (!DECL_DEFAULTED_FN (fun) && !LAMBDA_TYPE_P (CP_DECL_CONTEXT (fun)) + && !(flag_implicit_constexpr + && !DECL_DECLARED_CONSTEXPR_P (fun) + && DECL_DECLARED_INLINE_P (fun)) && !is_instantiation_of_constexpr (fun)) { inform (DECL_SOURCE_LOCATION (fun), "%qD declared here", fun); + if (flag_implicit_constexpr && !maybe_constexpr_fn (fun) + && decl_defined_p (fun)) + inform (DECL_SOURCE_LOCATION (fun), + "%<-fimplicit-constexpr%> only affects %<inline%> functions"); return; } if (diagnosed == NULL) diff --git a/gcc/testsuite/g++.dg/DRs/dr2478.C b/gcc/testsuite/g++.dg/DRs/dr2478.C index 7f581ca..b229256 100644 --- a/gcc/testsuite/g++.dg/DRs/dr2478.C +++ b/gcc/testsuite/g++.dg/DRs/dr2478.C @@ -2,7 +2,7 @@ // { dg-do compile { target c++20 } } // Defeat -fimplicit-constexpr -int ii; +int ii; // { dg-prune-output "value of 'ii' is not usable in a constant expr" } template <typename T> struct S { diff --git a/gcc/testsuite/g++.dg/ext/fimplicit-constexpr1.C b/gcc/testsuite/g++.dg/ext/fimplicit-constexpr1.C new file mode 100644 index 0000000..fc4b282 --- /dev/null +++ b/gcc/testsuite/g++.dg/ext/fimplicit-constexpr1.C @@ -0,0 +1,8 @@ +// { dg-additional-options -fimplicit-constexpr } +// { dg-do compile { target c++14 } } + +void f() { } // { dg-message "'-fimplicit-constexpr' only affects 'inline' functions" } + +inline int g() { f(); return 42; } // { dg-error {non-'constexpr' function 'void f\(\)'} } + +constexpr int i = g(); // { dg-error {'int g\(\)' called in a constant expression} } |