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| author | Jason Merrill <jason@redhat.com> | 2020-01-30 13:12:05 -0500 |
|---|---|---|
| committer | Jason Merrill <jason@redhat.com> | 2020-01-30 13:47:48 -0500 |
| commit | 4dd468a042e19ef0fdbb1c53ca4060d4cb4972c5 (patch) | |
| tree | 7819466fed9b711211891322aea8d7dc4ff621a7 | |
| parent | 004ac7b780308dc899e565b887c7def0a6e100f2 (diff) | |
| download | gcc-4dd468a042e19ef0fdbb1c53ca4060d4cb4972c5.zip gcc-4dd468a042e19ef0fdbb1c53ca4060d4cb4972c5.tar.gz gcc-4dd468a042e19ef0fdbb1c53ca4060d4cb4972c5.tar.bz2 | |
c++: Fix -Wtype-limits in templates.
When instantiating a template tsubst_copy_and_build suppresses -Wtype-limits
warnings about e.g. == always being false because it might not always be
false for an instantiation with other template arguments. But we should
warn if the operands don't depend on template arguments.
PR c++/82521
* pt.c (tsubst_copy_and_build) [EQ_EXPR]: Only suppress warnings if
the expression was dependent before substitution.
| -rw-r--r-- | gcc/cp/ChangeLog | 6 | ||||
| -rw-r--r-- | gcc/cp/pt.c | 12 | ||||
| -rw-r--r-- | gcc/testsuite/g++.dg/warn/Wtype-limits3.C | 13 |
3 files changed, 27 insertions, 4 deletions
diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog index a402b97..f260d5d 100644 --- a/gcc/cp/ChangeLog +++ b/gcc/cp/ChangeLog @@ -1,3 +1,9 @@ +2020-01-29 Jason Merrill <jason@redhat.com> + + PR c++/82521 + * pt.c (tsubst_copy_and_build) [EQ_EXPR]: Only suppress warnings if + the expression was dependent before substitution. + 2020-01-30 Bin Cheng <bin.cheng@linux.alibaba.com> * coroutines.cc (act_des_fn): New. diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c index 416ff63..40ff3c3 100644 --- a/gcc/cp/pt.c +++ b/gcc/cp/pt.c @@ -19279,10 +19279,14 @@ tsubst_copy_and_build (tree t, case MEMBER_REF: case DOTSTAR_EXPR: { - warning_sentinel s1(warn_type_limits); - warning_sentinel s2(warn_div_by_zero); - warning_sentinel s3(warn_logical_op); - warning_sentinel s4(warn_tautological_compare); + /* If T was type-dependent, suppress warnings that depend on the range + of the types involved. */ + bool was_dep = uses_template_parms (t); + warning_sentinel s1(warn_type_limits, was_dep); + warning_sentinel s2(warn_div_by_zero, was_dep); + warning_sentinel s3(warn_logical_op, was_dep); + warning_sentinel s4(warn_tautological_compare, was_dep); + tree op0 = RECUR (TREE_OPERAND (t, 0)); tree op1 = RECUR (TREE_OPERAND (t, 1)); tree r = build_x_binary_op diff --git a/gcc/testsuite/g++.dg/warn/Wtype-limits3.C b/gcc/testsuite/g++.dg/warn/Wtype-limits3.C new file mode 100644 index 0000000..b9059ac --- /dev/null +++ b/gcc/testsuite/g++.dg/warn/Wtype-limits3.C @@ -0,0 +1,13 @@ +// PR c++/82521 +// { dg-additional-options "-Wtype-limits" } + +template <typename T> +const char * g(const unsigned char value) +{ + return value == -1 ? "-1" : "no"; // { dg-warning "always false" } +} + +int main() +{ + g<int>(-1); +} |