Fix package error message line numbers (#8271)

Line numbers were reported as zero-indexed, but we need to adjust.

1 files changed, 20 insertions, 12 deletions

diff --git a/lib/spack/spack/build_environment.py b/lib/spack/spack/build_environment.py
index c2d91902a4..59af563c92 100644
--- a/lib/spack/spack/build_environment.py
+++ b/lib/spack/spack/build_environment.py
@@ -775,23 +775,31 @@ def get_package_context(traceback, context=3):
             if isinstance(obj, spack.package.PackageBase):
                 break
 
-    # we found obj, the Package implementation we care about.
-    # point out the location in the install method where we failed.
-    lines = []
-    lines.append("%s:%d, in %s:" % (
-        inspect.getfile(frame.f_code), frame.f_lineno, frame.f_code.co_name
-    ))
+    # We found obj, the Package implementation we care about.
+    # Point out the location in the install method where we failed.
+    lines = [
+        '{0}:{1:d}, in {2}:'.format(
+            inspect.getfile(frame.f_code),
+            frame.f_lineno - 1,  # subtract 1 because f_lineno is 0-indexed
+            frame.f_code.co_name
+        )
+    ]
 
     # Build a message showing context in the install method.
     sourcelines, start = inspect.getsourcelines(frame)
 
-    fl = frame.f_lineno - start
-    start_ctx = max(0, fl - context)
-    sourcelines = sourcelines[start_ctx:fl + context + 1]
+    # Calculate lineno of the error relative to the start of the function.
+    # Subtract 1 because f_lineno is 0-indexed.
+    fun_lineno = frame.f_lineno - start - 1
+    start_ctx = max(0, fun_lineno - context)
+    sourcelines = sourcelines[start_ctx:fun_lineno + context + 1]
+
     for i, line in enumerate(sourcelines):
-        is_error = start_ctx + i == fl
-        mark = ">> " if is_error else "   "
-        marked = "  %s%-6d%s" % (mark, start_ctx + i, line.rstrip())
+        is_error = start_ctx + i == fun_lineno
+        mark = '>> ' if is_error else '   '
+        # Add start to get lineno relative to start of file, not function.
+        marked = '  {0}{1:-6d}{2}'.format(
+            mark, start + start_ctx + i, line.rstrip())
         if is_error:
             marked = colorize('@R{%s}' % marked)
         lines.append(marked)