mbox series

[0/3] Track lifetimes in constant evaluation [PR70331,...]

Message ID 20230328113230.19975-1-nathanieloshead@gmail.com
Headers
Series Track lifetimes in constant evaluation [PR70331,...] |

Message

Nathaniel Shead March 28, 2023, 11:32 a.m. UTC 
  The first patch fixes PR70331, PR96630, and PR98675 regarding
constexpr evaluation not correctly diagnosing uses of dangling
references and pointers. The following two patches clean up and improve
some of the errors that are generated by this change, but aren't
strictly necessary.

This is my first change to the frontend, so any feedback is welcome. In
particular, I'm not sure if the way I went about the fix was correct:
for simplicity and efficiency's sake I added a new flag to
tree_decl_common, but this feels somewhat overkill for what is otherwise
a very locally useful property. 

Another option here would be to add a new lookup table to
constexpr_global_ctx which tracks what decls are in lifetime, but I
expect that to negatively impact performance. I haven't done any
benchmarks on this however.

Bootstrapped and regression tested on x86_64 linux.

---

Nathaniel Shead (3):
  c++: Track lifetimes in constant evaluation [PR70331,PR96630,PR98675]
  c++: Improve constexpr error for dangling local variables
  c++: Improve location information in constexpr evaluation

 gcc/cp/constexpr.cc                           | 149 ++++++++++++------
 gcc/cp/module.cc                              |   2 +
 gcc/cp/semantics.cc                           |   5 +-
 gcc/cp/typeck.cc                              |   5 +-
 gcc/print-tree.cc                             |   4 +
 gcc/testsuite/g++.dg/cpp0x/constexpr-48089.C  |  10 +-
 gcc/testsuite/g++.dg/cpp0x/constexpr-diag3.C  |   2 +-
 gcc/testsuite/g++.dg/cpp0x/constexpr-ice20.C  |   2 +-
 gcc/testsuite/g++.dg/cpp1y/constexpr-89481.C  |   3 +-
 .../g++.dg/cpp1y/constexpr-lifetime1.C        |  14 ++
 .../g++.dg/cpp1y/constexpr-lifetime2.C        |  20 +++
 .../g++.dg/cpp1y/constexpr-lifetime3.C        |  13 ++
 .../g++.dg/cpp1y/constexpr-lifetime4.C        |  11 ++
 .../g++.dg/cpp1y/constexpr-lifetime5.C        |  11 ++
 gcc/testsuite/g++.dg/cpp1y/constexpr-union5.C |   4 +-
 gcc/testsuite/g++.dg/cpp1y/pr68180.C          |   4 +-
 .../g++.dg/cpp1z/constexpr-lambda6.C          |   4 +-
 gcc/testsuite/g++.dg/cpp2a/bit-cast11.C       |  10 +-
 gcc/testsuite/g++.dg/cpp2a/bit-cast12.C       |  10 +-
 gcc/testsuite/g++.dg/cpp2a/bit-cast14.C       |  14 +-
 gcc/testsuite/g++.dg/cpp2a/constexpr-98122.C  |   4 +-
 .../g++.dg/cpp2a/constexpr-dynamic17.C        |   5 +-
 gcc/testsuite/g++.dg/cpp2a/constexpr-init1.C  |   5 +-
 gcc/testsuite/g++.dg/cpp2a/constexpr-new12.C  |   6 +-
 gcc/testsuite/g++.dg/cpp2a/constexpr-new3.C   |  10 +-
 gcc/testsuite/g++.dg/ext/constexpr-vla2.C     |   4 +-
 gcc/testsuite/g++.dg/ext/constexpr-vla3.C     |   4 +-
 gcc/testsuite/g++.dg/ubsan/pr63956.C          |   4 +-
 .../g++.dg/warn/Wreturn-local-addr-6.C        |   3 -
 gcc/tree-core.h                               |   5 +-
 gcc/tree.h                                    |   6 +
 .../25_algorithms/equal/constexpr_neg.cc      |   7 +-
 32 files changed, 247 insertions(+), 113 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime1.C
 create mode 100644 gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime2.C
 create mode 100644 gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime3.C
 create mode 100644 gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime4.C
 create mode 100644 gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime5.C