Fix travis yml for *_severe targets

We want to run the `*_severe` debug and test targets; thus, we need to enable ptrace capability for (L/A)SAN which is currently not possible
with container-based builds on travis-ci

TODO: revert to `sudo: false` (i.e., container-based builds) once the following are fixed/made possible
 - google/sanitizers#764
 - travis-ci/travis-ci#9033

.travis.yml

@@ -1,5 +1,16 @@
 language: cpp
 
+# We want to run the `*_severe` debug and test targets; thus, we need
+# to enable ptrace capability for (L/A)SAN which is currently not possible
+# with container-based builds on travis-ci
+# TODO: revert to `sudo: false` once the following are fixed/made possible
+# - https://github.com/google/sanitizers/issues/764
+# - https://github.com/travis-ci/travis-ci/issues/9033
+sudo: required
+
+matrix:
+  fast_finish: true
+
 # We want to run the `*_severe` debug and test targets; thus, we need
 # g++ >= 4.9 and clang++ >= 3.5
 compiler:

makefile

@@ -64,10 +64,9 @@ warning_flags = -Wall -Wextra
 # Don't use 'warning_flags_severe*' for production builds and rSOILWAT2
 warning_flags_severe = $(warning_flags) -Wpedantic -Werror
 warnings_flags_severe_cxx = $(warning_flags_severe) -Wno-error
-	# TODO: address underlying problems so that we can eventually add -Werror:
-	#  - clang++: "treating 'c' input as 'c++' when in C++ mode"
-	#  - ISO C++ forbids variable length array: (clang++ uses -Wvla-extension
-	#    whereas g++ uses -Wvla) --> cannot compile c++ unit tests with -Werror
+	# TODO: address underlying problems so that we can eliminate `-Wno-error`:
+	#  - compiler warning: treating 'c' input as 'c++' when in C++ mode, this behavior is deprecated (https://github.com/DrylandEcology/SOILWAT2/issues/208)
+	#  - compiler warning: variable length arrays (https://github.com/DrylandEcology/SOILWAT2/issues/214)
 
 # Instrumentation options for debugging and testing
 instr_flags = -fstack-protector-all