https://gcc.gnu.org/g:dabaca84b2bce49d2c5e9c98f88cf13ea61a7604
commit r15-10552-gdabaca84b2bce49d2c5e9c98f88cf13ea61a7604 Author: Nathaniel Shead <[email protected]> Date: Sun Nov 23 23:24:39 2025 +1100 c++/modules: Stream all REQUIRES_EXPR_PARMS [PR122789] We don't generally stream the TREE_CHAIN of a DECL, as this would cause us to unnecessarily walk into the next member in its scope chain any time it was referenced by an expression. Unfortunately, REQUIRES_EXPR_PARMS is a tree chain of PARM_DECLs, so we were only ever streaming the first parameter. This meant that when a parameter's type could not be tsubst'd we would ICE instead of returning false. This patch special-cases REQUIRES_EXPR to always stream the chain of decls in its first operand. As a drive-by improvement we also remove a fixme about checking uncontexted PARM_DECLs. PR c++/122789 gcc/cp/ChangeLog: * module.cc (trees_out::core_vals): Treat REQUIRES_EXPR specially and stream the chained decls of its first operand. (trees_in::core_vals): Likewise. (trees_out::tree_node): Check the PARM_DECLs we see are what we expect. gcc/testsuite/ChangeLog: * g++.dg/modules/concept-12_a.C: New test. * g++.dg/modules/concept-12_b.C: New test. Signed-off-by: Nathaniel Shead <[email protected]> Reviewed-by: Jason Merrill <[email protected]> (cherry picked from commit 53b4e1d951eaf5bbb2fcedfdd156d80a4160878a) Diff: --- gcc/cp/module.cc | 37 +++++++++++++++++++---------- gcc/testsuite/g++.dg/modules/concept-12_a.C | 6 +++++ gcc/testsuite/g++.dg/modules/concept-12_b.C | 5 ++++ 3 files changed, 36 insertions(+), 12 deletions(-) diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc index 8490b64e2330..9b1283692d1a 100644 --- a/gcc/cp/module.cc +++ b/gcc/cp/module.cc @@ -6407,13 +6407,19 @@ trees_out::core_vals (tree t) if (has_warning_spec (t)) u (get_warning_spec (t)); - /* Walk in forward order, as (for instance) REQUIRES_EXPR has a - bunch of unscoped parms on its first operand. It's safer to - create those in order. */ bool vl = TREE_CODE_CLASS (code) == tcc_vl_exp; - for (unsigned limit = (vl ? VL_EXP_OPERAND_LENGTH (t) - : TREE_OPERAND_LENGTH (t)), - ix = unsigned (vl); ix != limit; ix++) + unsigned limit = (vl ? VL_EXP_OPERAND_LENGTH (t) + : TREE_OPERAND_LENGTH (t)); + unsigned ix = unsigned (vl); + if (code == REQUIRES_EXPR) + { + /* The first operand of a REQUIRES_EXPR is a tree chain + of PARM_DECLs. We need to stream this separately as + otherwise we would only stream the first one. */ + chained_decls (REQUIRES_EXPR_PARMS (t)); + ++ix; + } + for (; ix != limit; ix++) WT (TREE_OPERAND (t, ix)); } else @@ -6989,9 +6995,15 @@ trees_in::core_vals (tree t) put_warning_spec (t, u ()); bool vl = TREE_CODE_CLASS (code) == tcc_vl_exp; - for (unsigned limit = (vl ? VL_EXP_OPERAND_LENGTH (t) - : TREE_OPERAND_LENGTH (t)), - ix = unsigned (vl); ix != limit; ix++) + unsigned limit = (vl ? VL_EXP_OPERAND_LENGTH (t) + : TREE_OPERAND_LENGTH (t)); + unsigned ix = unsigned (vl); + if (code == REQUIRES_EXPR) + { + REQUIRES_EXPR_PARMS (t) = chained_decls (); + ++ix; + } + for (; ix != limit; ix++) RTU (TREE_OPERAND (t, ix)); } @@ -10022,9 +10034,10 @@ trees_out::tree_node (tree t) break; case PARM_DECL: - /* REQUIRES_EXPRs have a tree list of uncontexted - PARM_DECLS. It'd be nice if they had a - distinguishing flag to double check. */ + /* REQUIRES_EXPRs have a chain of uncontexted PARM_DECLS, + and an implicit this parm in an NSDMI has no context. */ + gcc_checking_assert (CONSTRAINT_VAR_P (t) + || DECL_NAME (t) == this_identifier); break; } goto by_value; diff --git a/gcc/testsuite/g++.dg/modules/concept-12_a.C b/gcc/testsuite/g++.dg/modules/concept-12_a.C new file mode 100644 index 000000000000..9d370d35bab6 --- /dev/null +++ b/gcc/testsuite/g++.dg/modules/concept-12_a.C @@ -0,0 +1,6 @@ +// PR c++/122789 +// { dg-additional-options "-fmodules -fconcepts" } +// { dg-module-cmi M } + +export module M; +template <typename T> constexpr bool b = requires(int, typename T::U x) { x; }; diff --git a/gcc/testsuite/g++.dg/modules/concept-12_b.C b/gcc/testsuite/g++.dg/modules/concept-12_b.C new file mode 100644 index 000000000000..83353caeacca --- /dev/null +++ b/gcc/testsuite/g++.dg/modules/concept-12_b.C @@ -0,0 +1,5 @@ +// PR c++/122789 +// { dg-additional-options "-fmodules -fconcepts" } + +module M; +static_assert(!b<int>);
