[flang][preprocessor] Fixed-form continuation across preprocessing di… (#95332)

…rective

Implement fixed-form line continuation when the continuation line is the
result of text produced by an #include or other preprocessing directive.
This accommodates the somewhat common practice of putting dummy or
actual arguments into a header file and #including it into several code
sites.

Fixes https://github.com/llvm/llvm-project/issues/78928.

1 files changed, 8 insertions, 4 deletions

diff --git a/flang/lib/Parser/token-sequence.cpp b/flang/lib/Parser/token-sequence.cpp
index 40560bb..133e60b 100644
--- a/flang/lib/Parser/token-sequence.cpp
+++ b/flang/lib/Parser/token-sequence.cpp
@@ -378,9 +378,7 @@ const TokenSequence &TokenSequence::CheckBadFortranCharacters(
   return *this;
 }
 
-const TokenSequence &TokenSequence::CheckBadParentheses(
-    Messages &messages) const {
-  // First, a quick pass with no allocation for the common case
+bool TokenSequence::BadlyNestedParentheses() const {
   int nesting{0};
   std::size_t tokens{SizeInTokens()};
   for (std::size_t j{0}; j < tokens; ++j) {
@@ -394,8 +392,14 @@ const TokenSequence &TokenSequence::CheckBadParentheses(
       }
     }
   }
-  if (nesting != 0) {
+  return nesting != 0;
+}
+
+const TokenSequence &TokenSequence::CheckBadParentheses(
+    Messages &messages) const {
+  if (BadlyNestedParentheses()) {
     // There's an error; diagnose it
+    std::size_t tokens{SizeInTokens()};
     std::vector<std::size_t> stack;
     for (std::size_t j{0}; j < tokens; ++j) {
       CharBlock token{TokenAt(j)};