From 4155de721b700ea122cfa81058b146a2bd7e5055 Mon Sep 17 00:00:00 2001
From: Wilson Snyder <wsnyder@wsnyder.org>
Date: Fri, 26 Mar 2021 23:01:58 -0400
Subject: [PATCH] Fix Cygwin example compile issues (#2856).

---
 Changes                              | 1 +
 examples/make_protect_lib/Makefile   | 6 ++++++
 examples/make_tracing_c/Makefile     | 7 ++++++-
 examples/make_tracing_c/Makefile_obj | 8 ++++++--
 4 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/Changes b/Changes
index a69c14979..d3e675d92 100644
--- a/Changes
+++ b/Changes
@@ -25,6 +25,7 @@ Verilator 4.201 devel
 * Fix false TIMESCALEMOD on generate-ignored instances (#2838). [Kaleb Barrett]
 * Fix --output-split with class extends (#2839). [Iru Cai]
 * Fix false WIDTHCONCAT on casted constant (#2849). [Rupert Swarbrick]
+* Fix Cygwin example compile issues (#2856). [Mark Shaw]
 
 
 Verilator 4.200 2021-03-12
diff --git a/examples/make_protect_lib/Makefile b/examples/make_protect_lib/Makefile
index 319ce5c4a..215df0396 100644
--- a/examples/make_protect_lib/Makefile
+++ b/examples/make_protect_lib/Makefile
@@ -36,6 +36,12 @@ VERILATOR_FLAGS += -cc
 VERILATOR_FLAGS += -Os -x-assign 0
 # Warn abount lint issues; may not want this on less solid designs
 VERILATOR_FLAGS += -Wall
+# This example does not use vl_time_stamp but rather
+# VerilatedContext::timeInc(), so to avoid a linker error on cygwin which
+# does not support weak symbols, we need to define VL_TIME_CONTEXT *in CPP*
+# to not compile in the vl_time_stamp using code.
+VERILATOR_FLAGS += -CFLAGS -DVL_TIME_CONTEXT
+
 # Make waveforms
 TOP_VERILATOR_FLAGS = $(VERILATOR_FLAGS) --trace
 
diff --git a/examples/make_tracing_c/Makefile b/examples/make_tracing_c/Makefile
index e16d285fd..01556bc59 100644
--- a/examples/make_tracing_c/Makefile
+++ b/examples/make_tracing_c/Makefile
@@ -31,7 +31,6 @@ VERILATOR = $(VERILATOR_ROOT)/bin/verilator
 VERILATOR_COVERAGE = $(VERILATOR_ROOT)/bin/verilator_coverage
 endif
 
-VERILATOR_FLAGS =
 # Generate C++ in executable form
 VERILATOR_FLAGS += -cc --exe
 # Generate makefile dependencies (not shown as complicates the Makefile)
@@ -50,6 +49,12 @@ VERILATOR_FLAGS += --coverage
 #VERILATOR_FLAGS += --debug
 # Add this trace to get a backtrace in gdb
 #VERILATOR_FLAGS += --gdbbt
+# This example does not use vl_time_stamp but rather
+# VerilatedContext::timeInc(), so to avoid a linker error on cygwin which
+# does not support weak symbols, we need to define VL_TIME_CONTEXT *in CPP*
+# to not compile in the vl_time_stamp using code.
+VERILATOR_FLAGS += -CFLAGS -DVL_TIME_CONTEXT
+
 
 # Input files for Verilator
 VERILATOR_INPUT = -f input.vc top.v sim_main.cpp
diff --git a/examples/make_tracing_c/Makefile_obj b/examples/make_tracing_c/Makefile_obj
index 3177ef188..b757bd8d4 100644
--- a/examples/make_tracing_c/Makefile_obj
+++ b/examples/make_tracing_c/Makefile_obj
@@ -22,10 +22,13 @@ COMPILE.cc = $(OBJCACHE) $(CXX) $(CXXFLAGS) $(CPPFLAGS) $(TARGET_ARCH) -c
 #######################################################################
 # Compile flags
 
-# Override some default compile flags
+# Turn on creating .d make dependency files
 CPPFLAGS += -MMD -MP
+
+# Compile in Verilator runtime debugging, so +verilator+debug works
 CPPFLAGS += -DVL_DEBUG=1
-# Turn on some more flags (when configured appropriately)
+
+# Turn on some more compiler lint flags (when configured appropriately)
 # For testing inside Verilator, "configure --enable-ccwarn" will do this
 # automatically; otherwise you may want this unconditionally enabled
 ifeq ($(CFG_WITH_CCWARN),yes)	# Local... Else don't burden users
@@ -36,6 +39,7 @@ endif
 # Support class optimizations.  This includes the tracing and symbol table.
 # SystemC takes minutes to optimize, thus it is off by default.
 OPT_SLOW =
+
 # Fast path optimizations.  Most time is spent in these classes.
 OPT_FAST = -Os -fstrict-aliasing
 #OPT_FAST = -O