[flang-commits] [flang] [flang] Fix issue when macro is followed by OpenMP pragma (PR #123035)

[via flang-commits]

https://github.com/shivaramaarao created https://github.com/llvm/llvm-project/pull/123035

When a macro is followed by OpenMP pragma it is considered as comment and ignored. The function IsCompilerDirectiveSentinel expects the compiler directive argument without the prefix comment character. This is fixed in this commit.

Fixes #117693

>From bfc3d201256ecbdc77402758dae955048384ef78 Mon Sep 17 00:00:00 2001
From: Shivarama Rao <shivarama.rao at amd.com>
Date: Wed, 15 Jan 2025 09:44:04 +0000
Subject: [PATCH] When calling IsCompilerDirectiveSentinel,the prefix comment
 character need to be skipped.

Fixes #117693
---
 flang/lib/Parser/prescan.cpp           |  2 +-
 flang/test/Preprocessing/bug117693.f90 | 14 ++++++++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)
 create mode 100644 flang/test/Preprocessing/bug117693.f90

diff --git a/flang/lib/Parser/prescan.cpp b/flang/lib/Parser/prescan.cpp
index c5939a1e0b6c2c..50a9193d0a57b3 100644
--- a/flang/lib/Parser/prescan.cpp
+++ b/flang/lib/Parser/prescan.cpp
@@ -511,7 +511,7 @@ bool Prescanner::MustSkipToEndOfLine() const {
   if (inFixedForm_ && column_ > fixedFormColumnLimit_ && !tabInCurrentLine_) {
     return true; // skip over ignored columns in right margin (73:80)
   } else if (*at_ == '!' && !inCharLiteral_) {
-    return !IsCompilerDirectiveSentinel(at_);
+    return !IsCompilerDirectiveSentinel(at_+1);
   } else {
     return false;
   }
diff --git a/flang/test/Preprocessing/bug117693.f90 b/flang/test/Preprocessing/bug117693.f90
new file mode 100644
index 00000000000000..ced7927606e623
--- /dev/null
+++ b/flang/test/Preprocessing/bug117693.f90
@@ -0,0 +1,14 @@
+! RUN: %flang -fopenmp -E %s 2>&1 | FileCheck %s
+!CHECK: !$OMP DO SCHEDULE(STATIC)
+program main
+IMPLICIT NONE
+INTEGER:: I
+#define OMPSUPPORT
+!$ INTEGER :: omp_id
+!$OMP PARALLEL DO
+OMPSUPPORT !$OMP DO SCHEDULE(STATIC)
+DO I=1,100
+print *, omp_id
+ENDDO
+!$OMP END PARALLEL DO
+end program