Handle situations when cpp breaks a line into pieces.

There are situations in which GNU cpp breaks a single line of
input into multiple lines. These are indicated by linemarkers
that repeat the current line number, for instance:

  # 3 "file"
  this
  # 3  "file"
       is
  # 3  "file"
          all line three
  line four
  line five

We now remove these repeat linemarkers and collapse the
indicated lines back into one line, also eliminating the
leading whitespace that tries to preserve the column.

2 files changed, 38 insertions, 3 deletions

diff --git a/cppawk b/cppawk
index f7d0c33..565a445 100755
--- a/cppawk
+++ b/cppawk
@@ -70,6 +70,31 @@ die()
    exit 1
 }
 
+# Eliminate tracer lines in cpp output which continue a previous line, and
+# merge the continued lines into one.  Awk needs this because spurious newlines
+# break its syntax.
+collapse()
+{
+  awk '
+    $1 == "#" { if ($2 != curline || $3 != curfile)
+                { print
+                  if (line != "")
+                  { printf("%s\n", line);
+                    line = "" } }
+                startline = $2
+                curline = startline - 1
+                curfile = $3;
+                next }
+    1         { if (++curline > startline)
+                { if (line != "")
+                  { printf("%s\n", line)
+                    line = "" } }
+                else
+                { sub(/^[ \t]+/, "") }
+                line = line $0 }
+    END       { printf("%s\n", line); }'
+}
+
 prepro_opts="$prepro_opts -I$selfdir/cppawk-include"
 
 while [ $# -gt 0 ] ; do
@@ -120,7 +145,8 @@ trap 'rm -f $tmp_file' EXIT INT TERM
 if [ -n "$awk_file" ] ; then
   tmp_file=$(mktemp)
   $delhashbang "$awk_file" | \
-    eval '$prepro $incopt"$(dirname "$awk_file")" '"$prepro_opts -" > $tmp_file
+    eval '$prepro $incopt"$(dirname "$awk_file")" '"$prepro_opts -" | \
+    collapse > $tmp_file
   [ $prepro_only ] \
     && cat $tmp_file \
     || eval "$awk $awk_opts -f $tmp_file -- \"\$@\""
@@ -128,10 +154,10 @@ elif [ $# -gt 0 ] ; then
   tmp_file=$(mktemp)
   if [ $prepro_only ] ; then
     printf "%s" "$1" | $delhashbang | \
-      eval '$prepro $incopt"$(pwd)"'"$prepro_opts -"
+      eval '$prepro $incopt"$(pwd)"'"$prepro_opts - | collapse"
   else
     printf "%s" "$1" | $delhashbang | \
-      eval '$prepro $incopt"$(pwd)" '"$prepro_opts -" > $tmp_file
+      eval '$prepro $incopt"$(pwd)" '"$prepro_opts - | collapse" > $tmp_file
     shift
     eval "$awk $awk_opts -f $tmp_file -- \"\$@\""
   fi
diff --git a/testcases b/testcases
index 091f19d..8b7dc81 100644
--- a/testcases
+++ b/testcases
@@ -161,3 +161,12 @@ abc'def
 BEGIN { print __cppawk_ver >= 20220318 }'
 :
 1
+--
+30:
+./cppawk  '
+#include <limits.h>
+BEGIN {
+  print INT_MIN, INT_MIN, INT_MIN
+}'
+:
+-2147483648 -2147483648 -2147483648