[flang] Avoid spurious warnings from reading module files
When processing the literal constants of the various kinds of
INTEGER that are too large by 1 (e.g., 2147483648_4) in expression
analysis, emit a portability warning rather than a fatal error if
the literal constant appears as the operand to a unary minus, since
the folded result will be in range. And don't emit any warning if
the negated literal is coming from a module file -- f18 wrote the
module file and the warning would simply be confusing, especially to
the programmer that wrote (-2147483647_4-1) in the first place.
Further, emit portability warnings for the canonical expressions for
infinities and NaN (-1./0., 0./0., & 1./0.), but not when they appear
in a module file, for the same reason. The Fortran language has no
syntax for these special values so we have to emit expressions that
fold to them.
Fixes LLVM bugs https://github.com/llvm/llvm-project/issues/55086 and
https://github.com/llvm/llvm-project/issues/55081.
Differential Revision: https://reviews.llvm.org/D126584
diff --git a/flang/lib/Semantics/mod-file.cpp b/flang/lib/Semantics/mod-file.cpp
index 466a49f..2ba8918 100644
--- a/flang/lib/Semantics/mod-file.cpp
+++ b/flang/lib/Semantics/mod-file.cpp
@@ -1018,9 +1018,13 @@
if (!pair.second) {
return nullptr;
}
+ // Process declarations from the module file
Symbol &modSymbol{*pair.first->second};
modSymbol.set(Symbol::Flag::ModFile);
+ bool wasInModuleFile{context_.foldingContext().inModuleFile()};
+ context_.foldingContext().set_inModuleFile(true);
ResolveNames(context_, parseTree, topScope);
+ context_.foldingContext().set_inModuleFile(wasInModuleFile);
CHECK(modSymbol.has<ModuleDetails>());
CHECK(modSymbol.test(Symbol::Flag::ModFile));
if (isIntrinsic.value_or(false)) {
